GIFSQ — Global Institute for Food Safety & Quality Principle To achieve complete freedom from rejection on drained weight, the mean fill must sit at least three standard deviations above the lower control limit. The area table under the normal curve converts a distance in standard deviations (sigma) into the expected percentage of cans falling […]

GIFSQ — Global Institute for Food Safety & Quality Principle Points falling outside the trial control limits signal assignable causes of variation. Once those causes are found and corrected, the limits are recomputed without the out-of-control subgroups — out-of-control means are dropped from the X average while their ranges are kept if within limits, and […]

GIFSQ — Global Institute for Food Safety & Quality Principle No process turns out identical units, hour to hour or day to day. Control charts visualize trends against an upper and a lower limit — the dividing line between acceptable and unacceptable quality — so causes of defective product can be anticipated and corrected. The […]

GIFSQ — Global Institute for Food Safety & Quality Principle The FAO/WHO Codex Alimentarius sampling plan covers all prepackaged fruit and vegetable products — canned and frozen fruits and vegetables, juices, jams, jellies and marmalades, tomato products — at an AQL of 6.5. A lot or production run with 6.5% defective units is accepted approximately […]

GIFSQ — Global Institute for Food Safety & Quality Principle Variable sampling plans use actual measurements of a quality characteristic — total soluble solids, juice yield — instead of good-or-bad classification. They need considerably smaller samples than attribute plans, give more information for the decision, and provide a better basis for improving quality. The limitation […]

GIFSQ — Global Institute for Food Safety & Quality Principle Every sampling plan can be fully described by its operating characteristic (OC) curve — probability of acceptance plotted against the per-cent defective in the lot. The curve shows both the producer’s and the consumer’s risk, and the steeper the curve, the better the plan discriminates […]

GIFSQ — Global Institute for Food Safety & Quality Principle When a lot arrives divided into sub-lots — crates, baskets, cartons — sampling is done in two stages: first select which sub-lots to open, then draw units from within the selected sub-lots. The number of sub-lots to sample comes from the same code-letter and single-sampling […]

GIFSQ — Global Institute for Food Safety & Quality Principle Double and multiple sampling plans cut inspection on lots that are clearly good or clearly poor, by deciding in stages instead of examining the whole sample at once. In double sampling, a first sample n₁ is judged against Ac₁/Re₁: the lot is accepted if defectives […]

GIFSQ — Global Institute for Food Safety & Quality Principle Inspection by attributes judges each unit only as acceptable or unacceptable — good or bad. It suits two kinds of characteristics: those that cannot be measured (scratches, damage), and those that could be measured but are not, because of time, cost or need. Inspection by […]

GIFSQ — Global Institute for Food Safety & Quality Principle Quality control exists to make sure production meets defined standards inside accepted tolerances — the book illustrates this with the FAO/WHO Codex Alimentarius Standards for canned fruits, vegetables, juices, jams, jellies and marmalades. Control has to cover three stages: the raw material, the process itself, […]

GIFSQ — Global Institute for Food Safety & Quality Principle The sample selected for examination must be representative of the lot; every piece must have an equal chance of being selected. In random sampling each item of the lot is serially numbered and the items to be examined are chosen from a table of random […]

GIFSQ — Global Institute for Food Safety & Quality Principle While the regression equation describes the form of the statistical dependence of y on x, the correlation coefficient r measures the degree or intensity of the linear relationship. Its values lie between +1 (perfect positive correlation) and −1 (perfect negative correlation); r = 0 means […]

GIFSQ — Global Institute for Food Safety & Quality Principle Regression deals with situations where the variation of one (dependent) variable is related to the variation of a second (independent) variable — for example, the increase in sugar content with maturity. When the paired observations plotted on a scatter diagram show a linear trend, a […]

GIFSQ — Global Institute for Food Safety & Quality Principle In a nested (sub-grouping) sampling design — lots containing sublots, sublots containing cases, cases containing cans — the total variation in the quality scores is broken down step by step into the components due to lots, sublots within lots, cases within sublots, and cans within […]

GIFSQ — Global Institute for Food Safety & Quality Principle When the means of more than two groups of observations are to be compared, the t-test is not applicable and the analysis of variance (F-test) is used. Using the additive property of variance, the observed variance is broken down into the component between lots and […]

GIFSQ — Global Institute for Food Safety & Quality Principle When panelists rank several samples in order of preference, the chi-square (χ²) test applied to the rank totals determines whether the differences among the samples are significant. If the null hypothesis of no real difference held, the rank totals would be nearly equal; a large […]

GIFSQ — Global Institute for Food Safety & Quality Principle In a paired comparison test the null hypothesis presupposes that there is no real difference between the two samples, so the responses should be equally divided between the two categories. The chi-square (χ²) test compares the observed frequencies with the expected frequencies; a large χ² […]

GIFSQ — Global Institute for Food Safety & Quality Principle The chi-square (χ²) test is used for testing the equality of the variance of a given lot with a specified value. The sample variance is scaled by the degrees of freedom and divided by the specified variance; the resulting χ² value is compared with the […]

GIFSQ — Global Institute for Food Safety & Quality Principle When paired scores are available — for example, when each panelist rates two samples of a product, or when two methods of analysis are compared on the same samples — the paired t-test (t-by-difference) removes the effect of differences between the pairs from the estimate […]

GIFSQ — Global Institute for Food Safety & Quality Principle The t-test compares the means of two groups of observations and assesses whether the difference between them can reasonably be ascribed to chance. The null hypothesis states that there is no real difference between the two lot means; the difference is divided by the standard […]

GIFSQ — Global Institute for Food Safety & Quality Principle The t-test is used to judge whether the mean of the lot from which a sample has been drawn differs significantly from a specified value. The null hypothesis states that there is no real difference between the lot mean and the specified value; the calculated […]

GIFSQ — Global Institute for Food Safety & Quality Principle When the sample size of a lot is very large and the chance of an event occurring is very small — for example, rot counts or insect fragments in spite of good manufacturing practice — the binomial distribution tends towards the Poisson distribution. Fitting the […]

GIFSQ — Global Institute for Food Safety & Quality Principle In a triangle test each trial presents three samples, of which one is different and two are the same, so the chance of picking the odd sample correctly by guessing is 1/3. The binomial distribution gives the probability that the odd sample is picked correctly […]

GIFSQ — Global Institute for Food Safety & Quality Principle Large sets of numerical data — for example, the weights of individual fruits in a lot — are condensed by arranging them in groups (class intervals) and counting how many observations fall in each group. The relation between the class intervals and their frequencies is […]

GIFSQ — Global Institute for Food Safety & Quality Principle A sample drawn from a lot is measured, and the quantities computed from the sample data — the statistics — are used to describe the lot. The arithmetic mean locates the centre of the data, the variance and its square root, the standard deviation, measure […]

GIFSQ — Global Institute for Food Safety & Quality Principle The optical rotation of a vinegar, measured in a polarimeter tube, distinguishes the types: malt and molasses vinegars are dextro-rotatory, cider and grape vinegars are laevo-rotatory, and spirit vinegar has no optical activity. Turbid or dark samples are clarified before reading, and a right-handed reading […]

GIFSQ — Global Institute for Food Safety & Quality Principle Bulk density is the weight of product held in a unit volume; it is measured because it matters in the packaging of the product. The weight of sample filling a cylinder of exactly 625 ml water capacity is weighed, and the bulk density in lb/cu […]

GIFSQ — Global Institute for Food Safety & Quality Principle Red colour is one of the most important quality attributes of tomato products. Of the tomato’s pigments, lycopene predominates, accounting for approximately 83% of the pigments present. In this rapid method, the pigments are extracted from the sample with benzene, and the colour is measured […]

GIFSQ — Global Institute for Food Safety & Quality Principle When the procedure is followed properly, the specific gravity method gives an accurate and quite rapid estimate of total solids. The specific gravity of whole juice, pulp or filtrate bears a reasonably close relationship to total solids, which are ascertained by referring to the tomato […]

GIFSQ — Global Institute for Food Safety & Quality Principle The breaking strength of the set jelly is measured as the water pressure required to force a weighted piston through the gel. The pressure at which the jelly breaks, read on a water manometer, is used to determine the grade of the pectin by reference […]

GIFSQ — Global Institute for Food Safety & Quality Principle Frozen concentrated juices gel when pectin concentration, sugar content, residual pectinesterase activity and pH combine unfavourably; freeze damage to the fruit, pulp content, pulp-and-juice finisher pressures and processing temperatures also affect it. The test incubates the concentrate under controlled conditions and classifies the degree of […]

GIFSQ — Global Institute for Food Safety & Quality Principle Concentrates are described as 4-, 5- or 6-fold, meaning one volume of concentrate dilutes to 4, 5 or 6 volumes of juice. The fold of concentration is assessed from the specific gravity or the refractive index. The specific gravity of the concentrate itself cannot be […]

GIFSQ — Global Institute for Food Safety & Quality Principle The suspended solids of citrus juices (fine pieces of juice sacs, membrane and other structural components — also called insoluble solids, centrifuge solids, bottom pulp or sinking pulp) are separated by centrifuging the juice in graduated long-cone tubes. The reading at the top of the […]

GIFSQ — Global Institute for Food Safety & Quality Principle Screened pulp is the coarser pulp material retained on a standard 20-mesh screen; it consists largely of juice-sac material provided by the cut-back juice. The average screened pulp of Florida citrus concentrates is of the order of 1%. Apparatus required 20-mesh screen (12.7 cm diameter […]

GIFSQ — Global Institute for Food Safety & Quality Principle The degree of carbonation is measured as the equilibrium head-space pressure of the sealed bottle at a known temperature, read on a pressure gauge driven through the crown cork. The gauge reading and the beverage temperature are converted to gas volumes using the book’s Table […]

GIFSQ — Global Institute for Food Safety & Quality Principle Consistency, often related to mouth feel, is influenced by the amount, size and shape of insoluble solids and the viscosity of the serum, and is an important quality factor. The apparent viscosity of unclarified juices is measured with the Lamb and Lewis capillary viscometer (adopted […]

GIFSQ — Global Institute for Food Safety & Quality Principle Good juice keeps the colour of its fruit variety: natural-looking, without browning or any off-colour. Orange juice colour is graded against prepared USDA colour standards: the juice sample is matched visually against a series of standard tubes under standardized lighting. Apparatus required USDA orange-juice colour […]

GIFSQ — Global Institute for Food Safety & Quality Principle Unfermented fruit and vegetable juices containing only traces of alcohol or essential oil always show a specific gravity above 1.0; the lower the soluble solids, the smaller the specific gravity, and sweet juices have higher specific gravity. The specific-gravity-bottle method is the reference method, giving […]

GIFSQ — Global Institute for Food Safety & Quality Principle The alcohol-insoluble solids (AIS) content of peas reflects maturity and serves as a quality factor for quick frozen peas. The prepared paste is boiled with slightly diluted alcohol; the solids are washed with alcohol until the filtrate runs clear, then dried and weighed. The residue […]

GIFSQ — Global Institute for Food Safety & Quality Principle The fibre content of beans increases with maturity and is a good index of quality. The thawed beans are washed free of covering material, boiled, deseeded, boiled in caustic solution, macerated, sieved and washed free of alkali; the dried fibrous residue is weighed and expressed […]

GIFSQ — Global Institute for Food Safety & Quality Principle Specific gravity is used to determine the maturity level of frozen sweet corn and peas: the weight of the sample is first determined in air and then in a liquid, and the specific gravity is calculated from the two weights. Apparatus required One-pan balance weighing […]

GIFSQ — Global Institute for Food Safety & Quality Principle The frozen package is thawed in a water bath under standardised conditions, the contents are drained on a standard sieve for a fixed time, and the drained weight is expressed as a percentage of the net weight of the package. Apparatus required Water bath maintained […]

GIFSQ — Global Institute for Food Safety & Quality Principle Quick frozen fruits and vegetables are thawed by a standardised procedure — in air or in water — chosen so that the product thaws rapidly without altering or degrading its characteristics, and without leaching soluble solids from cut surfaces. Procedure Use the entire package; for […]

GIFSQ — Global Institute for Food Safety & Quality Principle The fill of the container is determined by comparing the volume of the frozen fruit, measured by displacement in cold mineral oil, with the water capacity of the outer container. Apparatus required Overflow can: a watertight stainless steel tank, 23 cm (H) × 20 cm […]

GIFSQ — Global Institute for Food Safety & Quality Principle The net weight of the contents of a frozen package is obtained gravimetrically: the frozen package is weighed with its frost and ice, then the contents (including product particles and frost crystals) are removed, the empty package is air-dried, and the difference gives the net […]

GIFSQ — Global Institute for Food Safety & Quality Principle Frozen blocks often carry large temperature gradients — during or just after freezing, or after exposure to ambient air — and the maximum product temperature in storage and handling must be measured directly inside the product. A thin probe, pushed in roughly along the food’s […]

GIFSQ — Global Institute for Food Safety & Quality Principle Strings are removed from individual bean pods and hung so that each string supports a 250 g clamp assembly; a string that supports the weight for five seconds or longer is considered a tough string, and the pods containing them are weighed and expressed as […]

GIFSQ — Global Institute for Food Safety & Quality Principle Foreign bodies are separated according to their nature: glass fragments are recovered by liquefying solid or pasty foods with dilute nitric acid, light materials are separated on a fine sieve with a water stream, and heavy inorganic matter is separated by washing and sedimentation. Apparatus […]

GIFSQ — Global Institute for Food Safety & Quality Principle After the can is emptied and washed, its internal surface is examined for corrosion, lacquer defects and seam faults, and the seam dimensions are measured; swollen cans receive a special seam examination. Procedure Once the cans are emptied and washed, look over the inside surface […]

GIFSQ — Global Institute for Food Safety & Quality Principle The fill of the container with food is found by measuring how far the food falls short of the top of the container: the water capacity of the container and the water remaining after drawing off to the food level are weighed, and the fill […]

GIFSQ — Global Institute for Food Safety & Quality Principle The water capacity of a container is the volume of distilled water at 20 °C which the sealed metal or glass container will hold when completely filled; it is found by weighing the empty container and the container filled with distilled water at 20 °C. […]

GIFSQ — Global Institute for Food Safety & Quality Principle The net weight of the contents is the gross weight of the can minus the tare weight of the washed and dried empty can; the net volume is expressed as a percentage of the total volume of the can, calculated from the can height, seam […]

GIFSQ — Global Institute for Food Safety & Quality Principle Proper fill of canned peas is an alternative to drained weight: the container is considered completely filled when its contents, poured out and returned, reach a defined distance below the top of the container. Apparatus required Empty container of the same kind and size as […]

GIFSQ — Global Institute for Food Safety & Quality Principle The proportion of each fruit ingredient in canned fruit cocktail is found by separating the individual fruits from the drained product, weighing each, and expressing each weight as a percentage of the sum of all the fruit weights. Apparatus required Weighing balance Sample preparation For […]

GIFSQ — Global Institute for Food Safety & Quality Principle The drained weight is the weight of the solid product after the packing medium has been drained off under standard conditions of sieve and time; it is expressed as a percentage of the water capacity of the sealed container. A washed drained weight removes all […]

GIFSQ — Global Institute for Food Safety & Quality Principle The gross headspace is the distance from the top of the double seam to the surface of the contents of the can, measured with a headspace gauge; the net (actual) headspace is obtained by deducting the seam allowance from the gross reading. Apparatus required Seam […]

GIFSQ — Global Institute for Food Safety & Quality Principle Cut-out examination is the systematic opening and inspection of a canned product: the external condition of the can is recorded, the internal vacuum or pressure is measured with a gauge, and the contents are inspected for appearance, fill and visible defects before any analytical test […]

GIFSQ — Global Institute for Food Safety & Quality Principle Prepared products in which the rate of heat penetration is slow (tomato juice, puree, paste, ketchup and soup, fruit juices, concentrates and pulps) are often sterilized before canning and filled sufficiently hot to sterilize the containers and the closure. The National Canners Association recommends hot […]

GIFSQ — Global Institute for Food Safety & Quality Principle When high-temperature (270–290 °F) processes are used, the holding time can be reduced to a few seconds. The alignment chart (Fig. 25.25 of the book) computes the sterilization value of thermal processes for liquid and semi-liquid food products in the temperature range 260–300 °F, expressing […]

GIFSQ — Global Institute for Food Safety & Quality Principle The Nomogram Method of Olson and Stevens is a graphical solution of Ball’s Formula Method. Separate nomograms are used for products with a single straight-line heating curve and for products with a broken (two-slope) heating curve; process time or sterilizing value is found by drawing […]

GIFSQ — Global Institute for Food Safety & Quality Principle If the heating rate fₕ of a product in one can size is known, the heating rate in other can sizes is calculated using conduction factors (for conduction-heating products) or convection factors (for convection-heating products) tabulated for the standard can sizes. The j value is […]

GIFSQ — Global Institute for Food Safety & Quality Principle Products such as thick soups, mixed vegetables, syrup-packed sweet potatoes and cream-style corn exhibit broken heating curves — a definite shift from initial convection heating to conduction heating during the process, giving two straight-line portions after the initial lag. The process time is calculated with […]

GIFSQ — Global Institute for Food Safety & Quality Principle Ball’s Formula Method calculates the process mathematically rather than graphically, and — unlike the graphical methods — can be applied to any can size or retort temperature, provided the TDT and the heat penetration rates approximate straight lines on semi-log paper. The heating curve on […]

GIFSQ — Global Institute for Food Safety & Quality Principle For canned fruits, where the process is based on enzyme inactivation, the temperature at which the enzyme is inactivated in 1 min is found by extrapolation from the thermal inactivation curve and taken as the base temperature. The time required to inactivate the enzyme at […]

GIFSQ — Global Institute for Food Safety & Quality Principle Patashnik’s simplification of the General Method removes the need to plot the lethality curve once the z value is known: heat penetration readings are taken at equal time intervals, the L value for each reading is taken from the tables, and the integration under the […]

GIFSQ — Global Institute for Food Safety & Quality Principle Recommendations of time at a given temperature normally ignore the retort come-up time. With static retorts having an appreciable come-up time, a proportion of it — usually 40% — may be allowed as process time, and the actual process time is reduced accordingly. Materials required […]

GIFSQ — Global Institute for Food Safety & Quality Principle Ball’s improvement of the General Method constructs a hypothetical TDT curve passing through the point of 1 min at 250 °F (F = 1), so that the area under the lethality curve, expressed in unit sterilizing areas, gives the sterilizing (F) value of the process […]

GIFSQ — Global Institute for Food Safety & Quality Principle Schultz and Olson’s special coordinate (lethal-rate) paper removes the need to calculate the TDT at every temperature: the temperature scale is replaced by lethal-rate spacing, so the lethality curve is plotted directly from the heat penetration data, and the F value of the process is […]

GIFSQ — Global Institute for Food Safety & Quality Principle The General Method (also called the Graphical Method), developed by Bigelow et al., integrates graphically the lethal effects of all the time-temperature relationships existing at the cold point during heating and cooling. The rate of destruction of an organism per minute at any temperature is […]

GIFSQ — Global Institute for Food Safety & Quality Principle Adequate thermal process calculation requires accurate measurement of heating and cooling at the cold point of the container during a retort run. Thermocouples fixed at the cold point record the container temperatures throughout heating and cooling; the resulting heat penetration curve, together with the product, […]

GIFSQ — Global Institute for Food Safety & Quality Principle When a can is processed, all points within it are not at the same temperature. The zone of slowest heating — the cold point — is the zone most difficult to sterilize. When heating is by convection the cold point lies on the vertical axis […]

GIFSQ — Global Institute for Food Safety & Quality Principle The decimal reduction time (D value) of peroxidase — the time at a given temperature required to reduce the enzyme activity by 90% — is obtained by estimating the peroxidase activity quantitatively in the unheated sample and in samples heated for varying periods, and applying […]

GIFSQ — Global Institute for Food Safety & Quality Principle The thermal inactivation time (TIT) as measured needs correction for the delay in bringing the contents of the tube to the temperature of the water bath. The extent of inactivation during the come-up period is calculated by the graphical method of Bigelow et al., as […]

GIFSQ — Global Institute for Food Safety & Quality Principle Peroxidase is the most heat-resistant of the enzyme systems in fruits and is used as the index organism-equivalent for thermal process schedules based on enzyme inactivation. The thermal inactivation time (TIT) — the minimum heating time at a given temperature at which peroxidase activity disappears […]

GIFSQ — Global Institute for Food Safety & Quality Principle For acid fruit products the thermal process is often based on the inactivation of heat-resistant enzymes (peroxidase, pectinesterase, polyphenoloxidase), which are more heat-resistant than the spoilage microorganisms. The test material must reproduce the product as canned — same pulp, same syrup strength and ratio, same […]

GIFSQ — Global Institute for Food Safety & Quality Principle F values reported in the literature are often based on different initial numbers of cells and are therefore not comparable; D values are independent of initial numbers and can be compared directly. Because Esty and Meyer’s classical data for Cl. botulinum (a preparation containing 6 […]

GIFSQ — Global Institute for Food Safety & Quality Principle When the decimal reduction times (D values) determined at several temperatures are plotted on semi-log paper against temperature, a straight line is obtained — the thermal resistance curve (also called the phantom thermal death time curve). Its slope, measured as the number of °F required […]

GIFSQ — Global Institute for Food Safety & Quality Principle The death rate of microorganisms when exposed to heat follows a logarithmic course: equal percentages of the surviving cells die in each successive unit of time. The decimal reduction time D is the time required to reduce the bacterial population by 90% at a given […]

GIFSQ — Global Institute for Food Safety & Quality Principle Since the death of organisms follows a logarithmic rate, the heating time intervals for thermal death time (TDT) determination are chosen a definite logarithmic cycle apart. The experimental heating periods must be corrected for the delay in bringing the contents of the tube or can […]

GIFSQ — Global Institute for Food Safety & Quality Principle Unlike insect fragments and rodent hairs, fly eggs, larvae, maggots, some nematodes, heavy rodent excreta (pellets), sand and similar materials do not float in the oil layer but settle down. The flotation procedure is therefore carried out in reverse: when petrol is mixed vigorously with […]

GIFSQ — Global Institute for Food Safety & Quality Principle Insects, insect fragments and rodent hairs are often lighter than food and may be floated out in liquids heavier than water; mammalian hairs behave in the same way as the insect cuticle and may be separated by oil flotation. With the exception of fly larvae […]

GIFSQ — Global Institute for Food Safety & Quality Principle Sand, soil, glass and similar heavy foreign materials are separated from the food by sedimentation in a liquid of specific gravity near 1.49: the dense fragments settle out while the plant tissue tends to rise. In spices, sand, soil, stems and similar heavy matter may […]

GIFSQ — Global Institute for Food Safety & Quality Principle High bacterial counts indicate secondary spoilage that may have occurred in the factory through breakdown or careless cleaning methods. The rod-shaped bacteria are counted directly under the microscope on the same mount as that prepared for yeasts and spores, and the count per unit volume […]

GIFSQ — Global Institute for Food Safety & Quality Principle High counts of yeasts and spores indicate secondary spoilage that may have occurred in the factory through breakdown or careless cleaning methods. Since specifications have been laid down for their counts in tomato products, the organisms are counted directly under the microscope in a blood […]

GIFSQ — Global Institute for Food Safety & Quality Principle Mould filaments in a finished product indicate food decomposition before processing, whether from plant disease, secondary invasion of injured raw material, physiological disorders, or growth from inadequate cleaning of machinery (growth of Oospora species particularly indicates a plant clean-up is needed). The Howard mould counting […]

GIFSQ — Global Institute for Food Safety & Quality Principle Rotten portions in canned tomatoes are detected by individually inspecting the drained tomatoes, and by counting mould in the pulped tomato and in the drained juice using the Howard cell, since mould filaments are a reliable index of rotten raw material having gone into the […]

GIFSQ — Global Institute for Food Safety & Quality Principle Rot fragments are fragments of tomato tissue that carry attached mould filaments; in some cases they show up as nearly solid clumps of mould. In this method the tissue is stained with crystal violet, the surplus pulp is rinsed away through a sieve, and the […]

GIFSQ — Global Institute for Food Safety & Quality Principle Mould growth breaks down fruit and vegetable tissue to form rot, so the presence of mould filaments in a finished product is a reliable index of rotten raw material having gone into manufacture. Because tomato products are comminuted and cooked during manufacture, visual inspection and […]

GIFSQ — Global Institute for Food Safety & Quality Principle In French (green) beans, the factors contributing to sensory tenderness, appearance and flavour change together as the bean matures; in the Burpee stringless variety, the weight-to-length (W/L) ratio has been found, on the basis of ten physico-chemical characteristics studied during growth, to be closely correlated […]

GIFSQ — Global Institute for Food Safety & Quality Principle As peas and lima beans mature, their density increases; shelled peas are blanched and floated in brines of stated density, and the proportion sinking in each brine is counted. The United States Standards for grades of canned peas fix, for each grade, the maximum percentages […]

GIFSQ — Global Institute for Food Safety & Quality Principle Succulence or juiciness is associated with the moisture content of the product. In the succulometer, a weighed charge of the product is pressed in a cylindrical cell under a fixed pressure for a fixed time, and the volume of juice expressed is measured; the volume […]

GIFSQ — Global Institute for Food Safety & Quality Principle The Instron universal testing machine drives a moving crosshead vertically at selected speeds (0.05 to 50 cm/min) while a strain-gauge load system records the force; the recorder chart and the crosshead are synchronously driven, so the trace is a force-distance curve from which firmness, toughness, […]

GIFSQ — Global Institute for Food Safety & Quality Principle The General Foods Texturometer imitates mastication: an articulator drives a plunger up and down on the sample for two successive cycles (two “bites”), and the force-time curve so obtained yields the texture profile parameters — hardness, cohesiveness, elasticity (springiness), adhesiveness, fracturability (brittleness), gumminess and chewiness […]

GIFSQ — Global Institute for Food Safety & Quality Principle As French (green) beans mature they become fibrous and the force required to shear them increases. Using a single shear blade (similar to the Warner-Bratzler shear blade), the force required to shear beans placed edgewise and flat is measured; in tender beans the edgewise force […]

GIFSQ — Global Institute for Food Safety & Quality Principle As peas mature they become tougher and offer more resistance to cutting. In the texturometer for peas, a grid of blades is rotated at a constant speed through a second grid of peas so that the force on the second grid is counter-balanced by a […]

GIFSQ — Global Institute for Food Safety & Quality Principle The Magness-Taylor pressure tester measures the maximum force required to push a cylindrical metal probe into the flesh of a fruit to a given depth; the force recorded indicates the firmness of the fruit and is used to determine softening during maturity and ripening. The […]

GIFSQ — Global Institute for Food Safety & Quality Principle The Stormer viscometer measures consistency or viscosity by the time required for a rotor, driven by a falling weight, to make 100 revolutions in the sample. The number of seconds for 100 revolutions, measured against the time for the same number of revolutions in a […]

GIFSQ — Global Institute for Food Safety & Quality Principle The Adams consistometer overcomes the limitations of the Bostwick consistometer for cream style corn (small capacity, arc-shaped flow front, flow in one direction only) by measuring the unrestrained flow of a larger mass of sample in all directions over a disc engraved with concentric circles. […]

GIFSQ — Global Institute for Food Safety & Quality Principle Efflux-tube viscometers measure the time necessary for a fixed quantity of fluid to pass through an orifice or capillary under standard pressure. In the specially designed efflux-tube viscometer used for tomato puree, the sample is drawn up the tube by vacuum and then allowed to […]

GIFSQ — Global Institute for Food Safety & Quality Principle The Bostwick consistometer measures the consistency of viscous foods such as tomato ketchup and sauce on the theory that the length of flow of the released product along a channel is proportional to its consistency. A portion of the sample is held behind a triggered […]

GIFSQ — Global Institute for Food Safety & Quality Principle The Brookfield viscometer measures the torque on a rotating spindle (bob) immersed in the product; from the torque–speed relationship the fundamental consistency constants of a non-Newtonian product are obtained: the flow behaviour index (n), the consistency coefficient (K) and, where present, the yield stress (C). […]

GIFSQ — Global Institute for Food Safety & Quality Principle Fruit purees and juices are non-Newtonian fluids: their resistance to flow changes with the rate of shear, so a single viscosity figure does not describe them. In a tube viscometer, the product is forced through a capillary tube under measured pressure and the rate of […]

GIFSQ — Global Institute for Food Safety & Quality Principle The methods for measuring colour by reflectance locate the colour of any food in colour space by determining the three attributes of colour. For products which are transparent — like lime juice cordial and clarified apple, guava or grape juice — or for a product […]

GIFSQ — Global Institute for Food Safety & Quality Principle The Photovolt reflectance meter is a photoelectric tricolorimeter that makes use of three tristimulus filters — amber, green and blue. Evaluation of the colour of a sample involves three measurements, one with each filter, and the trichromatic coefficients X, Y and Z are computed from […]

GIFSQ — Global Institute for Food Safety & Quality Principle Photoelectric tricolorimeters make use of three filters which have spectral sensitivity curves similar to the spectral distribution curves of the CIE reference stimuli X, Y and Z. Evaluation of the colour of a sample involves three measurements using each filter. The Hunter colour and colour-difference […]

GIFSQ — Global Institute for Food Safety & Quality Principle Reduction of spectrophotometric data to the tristimulus values X, Y and Z is based on Grassmann’s laws. In the weighted ordinate method, the spectrum wavelengths are chosen at uniform intervals. In the selected ordinate method, instead, the intervals of spectrum selected correspond to uniform increments […]

GIFSQ — Global Institute for Food Safety & Quality Principle A spectrophotometric curve relating wavelength and intensity through the visible part of the spectrum (approximately 380–770 nm) gives a complete physical specification of colour and makes it possible to calculate the CIE tristimulus values X, Y and Z. Reduction of spectrophotometric data to the tristimulus […]

GIFSQ — Global Institute for Food Safety & Quality Principle The Lovibond tintometer is a subtractive colorimeter based on direct observation of an illuminated sample through a viewing tube. The instrument is provided with sets of red, yellow and blue glass slides to be used as permanent standards. The slides form an evenly graded series […]

GIFSQ — Global Institute for Food Safety & Quality Principle Disc colorimetry is an additive system based on the use of coloured discs. The discs have radial slits so that a number of them may be slipped together with varying portions of each showing; the discs are spun on a spindle at about 2,700 rpm […]

GIFSQ — Global Institute for Food Safety & Quality Principle In the visual matching of the colour of food against standard colours, the sample is compared directly with printed colour standards. The colour dictionary of Maerz and Paul is the most commonly used; it consists of 56 charts in which seven main groups of hues […]

GIFSQ — Global Institute for Food Safety & Quality Principle Optical filters are used in colorimeters (absorptiometers) for isolating a desired spectral region. They consist of coloured glass or coloured gelatin coated on glass and possess the property of selectively transmitting light from a specified region of the spectrum, the other regions being absorbed. The […]

GIFSQ — Global Institute for Food Safety & Quality Principle The shelf-life of a packaged food depends on (i) the reactivity of the food with deteriorating influences and (ii) the capacity of the package to protect the food from these influences. Next to microorganisms, oxygen is the most destructive agent; next in importance is the […]

GIFSQ — Global Institute for Food Safety & Quality Principle The graphical interpolation method is based on the principle that the rate of gain or loss of moisture of a product, at any given initial moisture content and atmospheric relative humidity, increases with increasing difference between the atmospheric and the product vapour pressures. The duration […]

GIFSQ — Global Institute for Food Safety & Quality Principle A product is in equilibrium with its environment when the rate of moisture loss from the product to the surrounding atmosphere equals the rate of moisture gained from the atmosphere. The relative humidity at which the substance will neither gain nor lose moisture under given […]

GIFSQ — Global Institute for Food Safety & Quality Principle Grease resistance of a packaging material is compared by the transudation time: coloured turpentine is applied to sand spread over the test specimen, and the elapsed time in seconds between the addition of the turpentine and the appearance of the first definite red stain on […]

GIFSQ — Global Institute for Food Safety & Quality Principle Tear strength, reported in grams, is the force necessary to continue tearing a sample after a nick has been made. In the Elmendorf tear tester, a sample is clamped to a pendulum and nicked; on release, the pendulum tears the specimen, and the scale registers […]

GIFSQ — Global Institute for Food Safety & Quality Principle Bursting strength is the hydrostatic pressure required to rupture the material: pressure is applied at an increasing rate through a rubber diaphragm to a circular area 1.2 inch in diameter. The material under test is initially flat and held rigidly at the circumference but free […]

GIFSQ — Global Institute for Food Safety & Quality Principle Tensile strength is a fundamental property indicative of the serviceability of a packaging material: it determines the resistance to rupture when the material is subjected to a pulling force. Elongation, measured on the same machine, is the extent to which a material will stretch before […]

GIFSQ — Global Institute for Food Safety & Quality Principle The test film is clamped to a gas transmission cell; test gas is admitted to one side of the specimen while the other side is evacuated. The gas permeates through the film into the evacuated chamber over a measured length of time, and the gas […]

GIFSQ — Global Institute for Food Safety & Quality Principle The cycle method tests the water vapour permeability of finished packages subjected to extremes of temperature and relative humidity when closed and sealed in the conventional manner. It is intended for shelf-size packages that are shipped in outside containers. The sealed package is cycled between […]

GIFSQ — Global Institute for Food Safety & Quality Principle The water vapour permeability of a finished package is determined as the rate at which water is transmitted into the sealed package from the test atmosphere (normally 90 ± 2% RH at 37.8 ± 1°C) surrounding it, while a desiccant or the product itself is […]

GIFSQ — Global Institute for Food Safety & Quality Principle The water vapour transmission rate (WVTR) of a packaging material is measured by the dish method: an open dish filled with desiccant is tightly covered with the test specimen and exposed to a controlled temperature and humidity. The desiccant gains weight as water vapour permeates […]

GIFSQ — Global Institute for Food Safety & Quality Principle Paper and paper products change their moisture content with the surrounding atmosphere, and their measured strength and permeability values depend on that moisture content. Test results are therefore only comparable when specimens are brought to a standard conditioned state before testing: a circulating atmosphere held […]

GIFSQ — Global Institute for Food Safety & Quality Principle Dimensional checking ensures that the bottle will perform satisfactorily during filling, packing and handling. The bottle height is measured with vernier instruments and the diameter is checked with ring gauges against maximum and minimum limits. Deviation often occurs in local areas of the bottle surface […]

GIFSQ — Global Institute for Food Safety & Quality Principle In a cylindrical bottle, the centre of the finish is intended to lie in the vertical plane through the joining faces of the body mould, vertically above the centre of the base. The horizontal distance by which the finish departs from this position is the […]

GIFSQ — Global Institute for Food Safety & Quality Principle The quality of the glass itself is determined using powdered glass prepared from the bottles. Alkalinity extracted from the powdered glass into water is titrated with 0.01 N HCl using methyl red indicator. Two procedures are given: a reflux extraction (Procedure A) and a more […]

GIFSQ — Global Institute for Food Safety & Quality Principle Glass is attacked by water, and the attack accelerates when repeated high-temperature sterilization (100–120 °C) of filled bottles is carried out. Alkali extracted from the glass changes the colour of methyl red indicator solution. In the whole-container test, the bottle is filled with acidified methyl […]

GIFSQ — Global Institute for Food Safety & Quality Principle The resistance of a glass container to internal pressure is tested by filling the bottle with water and applying pressure with a pump, a direct ram, or in a hydrostatic pressure tester. The pressure resistance is proportional to the wall thickness and inversely proportional to […]

GIFSQ — Global Institute for Food Safety & Quality Principle Glass containers break by active impact or by a series of small impacts. The resistance of the bottle to impact is tested either by dropping it from progressively greater heights onto a rigid surface or by striking it with a rigid pendulum whose fall height […]

GIFSQ — Global Institute for Food Safety & Quality Principle Thermal shock resistance is measured as the difference between the upper temperature (T₁) of the hot bath in which the containers are heated and the lower temperature (T₂) of the cold water bath into which they are transferred. The containers are examined for cracks or […]

GIFSQ — Global Institute for Food Safety & Quality Principle The capacity of a glass bottle is defined either as the brimful capacity or as the capacity to a stated filling height. A bottle is brimful when, standing on a level surface, it is filled with water until the centre of the water surface is […]

GIFSQ — Global Institute for Food Safety & Quality Principle A sound end seam rests on two things: the two hooks interlocking cleanly during seaming, and a thin film of lining compound sealing them. A poor seam can let air leak out or cooling water leak in — and with it, spoilage organisms. The seam […]

GIFSQ — Global Institute for Food Safety & Quality Principle Lab tests on plate and lacquer are only screening. The real verdict on acid and sulphur resistance comes from packed food: the candidate plate is canned up alongside a plate of known good performance and the two are compared over storage. A plate passes if […]

GIFSQ — Global Institute for Food Safety & Quality Principle The truest adhesion check is to stamp can ends from the lacquered sheet and look at them. In the laboratory the scotch-tape method stands in: the lacquer is scratched with a fine needle, tape is pressed on, and ripped off. It reliably catches poor adhesion, […]

GIFSQ — Global Institute for Food Safety & Quality Principle How a tin coating’s grain size sits relates to how it corrodes in some media — grain coarser than No. 9 (ASTM) is judged satisfactory. Grain is seen either under polarized light on the untouched surface or after a simple acid etch; the etching bath […]