Gary Tucker S.

Essentials of Thermal Processing


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culture‐single kind of micro‐organism, mixed culture‐two or more kinds of micro‐organisms growing together.Culture MediumAny substance or preparation suitable for and used for the growth and cultivation of micro‐organisms.D‐value (decimal reduction time)Time in minutes at a specified temperature required to destroy 90% of the micro‐organisms in a population.DeaerationRemoval of oxygen from produce juices to prevent adverse effects on juice properties.DehydrationA food processing unit operation resulting in the removal of water from the food generally to the point where spoilage is prevented.DetergentSurface‐active material or combination of surfactants designed for removal of unwanted contamination from the surface of an article.DeteriorationA non‐biological, physical, or chemical change in food which adversely affects quality.DetinningThe process of corrosion, where the internally plain tin coating is slowly dissolved by the food medium; rapid detinning refers to abnormally fast tin dissolution, caused by the presence of corrosion accelerators.DisinfectantAn agent that frees from infection by killing the vegetative cells of micro‐organisms.DisinfectionThe reduction, without adversely affecting the food, by means of hygienically satisfactory chemical agents and /or physical methods, of the number of micro‐organisms to a level that will not lead to harmful contamination of food.Double SeamTo attach an end to a can body by a method in which five (5) thicknesses of plate are interlocked or folded and pressed firmly together. A joint formed by interlocking the edges of both the end and body of a can.Drained WeightWeight of the solid portion of the product after draining the covering liquid for a specified time with the appropriate sieve.EffluentWaste water or other liquid, partially or completely treated or untreated, flowing out of a process operation, processing plant, or treatment plant.EmulsionSystem consisting of two incompletely miscible liquids, one being dispersed as finite globules in the other. A small amount of a third substance may render the dispersion stable. The liquid broken up into globules is the dispersed (discontinuous) phase; the surrounding liquid is the external (continuous) phase.EndotoxinA toxin produced with an organism liberated only when the organism disintegrates.EnterotoxinA toxin specific for cells of the intestine. Gives rise to symptoms of food poisoning.Enzymatic BrowningThe darkening of plant tissues or products produced by enzymatic reactions.EnzymeA compound of biological origin which accelerates a specific chemical reaction.Equilibrium pHThe pH of the macerated (thoroughly blended) contents of the product container.Equilibrium Relative HumidityThe relative humidity of the ambient atmosphere surrounding a substance when the substance neither gains nor loses moisture.Escherichia ColiThe strains of E. coli that produce an entero‐pathogenic food poisoning syndrome.ExotoxinA toxin excreted by a micro‐organism into the surrounding medium.F‐valueThe number of minutes required to destroy a stated number of micro‐organisms at a defined temperature, usually l21.1°C (250°F), and when the z‐value is 10°C (18°F). “F” value is a common term employed in the canning industry to express the lethality or sterilizing value of a sterilization process. See also z‐value.Facultative BacteriaBacteria which can exist and reproduce under either aerobic or anaerobic conditions.FahrenheitA temperature scale in which 32°F represents the freezing point of water and 212°F represents its boiling point.FermentationThe action of micro‐organisms upon foods. Anaerobic respiration. Usually fermentation is undesirable, but sometimes it is produced intentionally, such as in the manufacture of vinegar from apple cider.Fill WeightThe weight of the product before processing. It does not include the weight of the container or covering liquid.Flash PasteurizationProcess in which the material is held at a much higher temperature than in normal pasteurization, but for a considerably shorter period.Flat soursThermophilic and thermoduric bacteria, facultative anaerobes that attack carbohydrates with the production of acids, but without gas formation. Flat‐sour spoiled canned foods therefore show no swelling of the ends.Flexible ContainerA container where the shape or contours of the filled, sealed container are affected by the enclosed product.FlipperA can having both ends flat, but with insufficient vacuum to hold the ends in place, thus a sharp blow will cause the end to become convex, but both ends may be pressed to their normal position.Food InfectionAn illness caused by an infection produced by invasion, growth and damage to the tissue of the host due to the ingestion of viable pathogenic micro‐organisms associated with the food.Food IntoxicationAn illness resulting from the ingestion of bacterial toxin with or without viable cells. The illness does not require actual growth of cells in the intestinal tract.Food PoisoningA general term applied to all stomach or intestinal disturbances due to food contaminated with certain micro‐organisms or their toxins.FortifiedFood to which specific nutrients have been added “enriched”.FungicideAny substance that destroys fungi or inhibits the growth of spores or hyphae. Legally, sometimes the term is interpreted as also including yeasts and bacteria.Fungistatic AgentPrevents growth of fungi (moulds) without necessarily killing the existing cells.GRASGenerally Recognized as Safe.HACCPHazard Analysis of Critical Control Points. An inspectional approach that determines what points in the process are critical for the safety of the product and how well the firm controls these points.HalophilicCan grow or survive in a medium with a relatively high salt concentration.Hard SwellSpoilage in which can ends are swelled too hard to be readily depressed by applying thumb pressure.Headspace, GrossThe vertical distance between the level of the product (generally the liquid surface) and the inside surface of the lid in an upright rigid container (the top of the double seam of a can or the top edge of a glass jar).HeadspaceThe vertical distance between the level of the product (generally the liquid surface) and the inside surface of the lid in an upright, rigid container having a double seam, such as a can.Heat ExchangerEquipment for heating or cooling liquids rapidly by providing a large surface area and turbulence for the rapid and efficient transfer of heat.Heat, LatentHeat absorbed or liberated in a change of physical state such as evaporation, condensation, freezing or sublimation. Expressed as BTU per lb., kCal per kg or joules per kg.Heating CurveA graphical representation of the rate of temperature change in the food throughout the heat process; this is usually plotted on semi‐log graph paper so that the temperature on an inverted log scale is plotted against time on a linear scale.Heating factor (fh)Time taken for the heating or cooling curve plotted on semi‐log coordinates to traverse one log cycle.HMFHydroxymethylfurfural. Is an organic compound derived from dehydration of certain sugars. HMF is practically absent in fresh food, but it is naturally generated in sugar‐containing food during heat‐treatments like drying or heat processing. HMF can be used as an indicator for excess heat‐treatment.IncubationHolding cultures of micro‐organisms under conditions favourable to their growth. Also, the holding of a sample at a specified period of time before examination.Incubation TimeThe time period during which micro‐organisms inoculated into a medium are allowed to grow.Initial Temperature (IT)The average temperature of the contents of the coldest container to be processed at the time the sterilizing cycle begins, as determined after thorough stirring or shaking of the filled and sealed container.InoculateThe artificial introduction of micro‐organisms into a system.InoculationThe artificial introduction of micro‐organisms into a growth medium. This can refer to the introduction of test organisms to food, to the accidental introduction of organism to food.InoculumThe material containing micro‐organisms used for inoculation.IntoxicationThe adverse physiological effects of an organism consuming a toxic material.Lag factor (j)The lag in achieving a logarithmic heating rate for the heating or cooling curve plotted on semi‐log coordinates.Latent HeatThe quantity of heat, measured in BTU’s or calories, necessary to change the physical state of a substance without changing its temperature.LethalCapable of causing death.Lethality Value (F‐value)This degree of sterility is referred to as commercial sterility. The F‐value is introduced as a standard on which to base the sterilization of food products. The F‐value is defined as the number of minutes which it takes to reduce the initial spore count of a certain micro‐organism to a desired safety level at a defined lethal reference temperature.Low‐acid FoodsAny food (other than alcoholic beverages) with a finished equilibrium pH greater than 4.6 (4.5 in Europe) and a water activity greater than 0.85.Maillard ReactionA group of organic reactions, especially between amino acids and reducing sugars, producing brown colour and flavour changes in many foods. Also known as non‐enzymatic browning.MouldsMicro‐organisms that belong to the fungi. Moulds are much less heat resistant than bacteria.MycotoxinsToxins produced by moulds or fungi.NestingContainers that fit within one another when stacked.Net Weight, MinimumThe weight of all the product in the container, including brine or sauce, but not including the weight of the container.Non‐NewtonianMaterials whose resistance to flow changes with a change in rate of shear.NutrientsCompounds that promote biological growth.OsmophilicCan