Читать книгу Essentials of Thermal Processing - Gary Tucker S., Gary S. Tucker - Страница 10

AcidA substance which increases the concentration of hydrogen ions (H+) in water, and reacts with a base to form a salt.Acid FoodsA food that has a natural pH of 4.6 or below (in Europe it is common to use pH 4.5 as the upper limit).Acidified Low‐Acid FoodA food which has been treated so as to attain an equilibrium pH of 4.6 (or 4.5 in Europe) or lower after heat processing.Acidified FoodA low‐acid food to which acid(s) or acid food(s) are added and which has a finished equilibrium pH of 4.6 or below and a water activity (aw) greater than 0.85.AcidulantAn acidifying agent, such as acetic acid or vinegar.AciduricMicro‐organisms that can grow in high acid foods, i.e., with a pH value below 3.0. Generally, are of low heat resistance.AerobesMicro‐organisms that need oxygen for growth. Obligate aerobes cannot survive in the absence of oxygen.AerobicLiving or active only in the presence of free oxygen.AnaerobesMicro‐organisms that grow in the absence of oxygen. Obligate anaerobes cannot survive in the presence of oxygen. Facultative anaerobes normally grow in oxygen, but can also grow in its absence.AnaerobicLiving or active in the absence of free oxygen.Anti‐MicrobialA compound which inhibits the growth of a microbe.AntioxidantsSubstances that retard the oxidative rancidity of fats, or the oxidation of other substances.Aseptic Processing and PackagingThe filling of a commercially sterile product into sterilised containers followed by hermetical sealing with a sterilised closure in an atmosphere free from micro‐organisms.AsepsisClean and free of micro‐organisms.AutoclaveA vessel in which high temperatures can be reached by using high steam pressure. Bacteria are destroyed more readily at elevated temperatures, and autoclaves are used to sterilize food, for example in cans.BacillusA rod‐shaped bacterium. Some Bacillus produce spores.Bacillus CereusSpore‐forming, rod‐shaped bacterium, aerobic to facultative aerobic, proteolytic. It produces gastroenteritis caused by the release of an exo‐enterotoxin during lysis of B. cereus in the intestinal tract.BactericideAny substance that destroys bacteria, although not necessarily the spores of bacteria.BentoniteColloidal clay used as an absorbent. Also used in model systems for determining rate of heat penetration.BiodegradabilitySusceptibility of a chemical compound to depolymerization by the action of biological agents.Biological Oxygen Demand (BOD)Micro‐organisms consume oxygen in their respiration. The BOD test determines uptake of oxygen by a contaminated material, e.g., sewage, water, etc., as a measure of microbial activity.BlanchingHeating by direct contact with hot water or live steam. It softens the tissues, eliminates air from the tissues, destroys enzymes, and washes away raw flavours.Body HookThat flange portion of the can body that is turned back for the formation of the double seam.Body MakerA machine for automatic forming of a cylindrical metal can or drums body from a body blank. In the manufacture of tin cans, the body maker may also automatically weld the side seam.Boiler ScaleDeposit left inside boilers caused by evaporation of water and precipitation of water‐soluble and insoluble substances.BotulismA poisoning caused by substances formed by the bacterium Clostridium botulinum under conditions of improper processing and storage of food. The spores of this bacterium are often found in soil and are likely to be present on soil‐contaminated food.Break‐Point ChlorinationAddition of chlorine to water beyond the point where chloramines are oxidized, and where further increases in the dosage of chlorine will result in a proportional increase of chlorine residual.BrinesSalt solutions used in canning and pickling.BrixThe measure of density of a solution, more particularly a solution containing sucrose, as determined by a hydrometer. Degrees Brix equal Percent sucrose in water solution at 20°C.Broken Heating CurveA heating curve which shows a distinct change in the rate of heat transfer such that the curve may be represented by two or more distinct straight lines.Broth MediumA liquid medium for growth of micro‐organisms.Browning ReactionA reaction in foods, usually deteriorative, involving amino (e.g., from amino acids or proteins) and carbonyl (e.g., from glucose) groups; this reaction often leads to a brown discolouration and sometimes to off‐flavours and changes in texture.BufferAny substance in a fluid which tends to resist the change in pH (hydrogen‐ion concentration) when acid or alkali is added.Canned FoodCommercially sterile food in hermetically sealed containers.CarbohydratesCarbohydrates are essential food nutrients that can get broken down into glucose to be used as energy. They are comprised of C, H and O. Examples include starches, sugars and fibre.CarcinogenA cancer causing agent.CationPositively charged ion such as K+, NH4+.Cationic SurfactantsIonic surface active agents in which the portion that associates with the internal phase is the cation. They include simple amine salts, quaternary ammonium salts, amino imides and imidazolines. Cationic surfactants often have germicidal, anticorrosive, and anti‐static properties.Celsius (°C)Temperature on a scale of 100° between the freezing point (0°) and the boiling point (100°) of water.Chemical Oxygen Demand (COD)An indirect measure of the biochemical load exerted on the oxygen content of a body of water when organic wastes are introduced into the water. When the wastes contain only readily available organic bacterial food and no toxic matter, the COD values can be correlated with BOD values obtained from the same wastes.ChlorinationBuilding up the chlorine content (as hypochlorous acid) to process or sanitize water supplies.ClostridiaGenus of spore forming bacteria. Clostridium botulinum is the most heat resistant of the food‐poisoning organisms; its growth is inhibited at pH 4.6 and below, thus it is only a problem in low‐acid foods. Produces an endotoxin, highly toxic in minute doses, but destroyed by heat. Destruction of this organism is generally accepted as the minimum standard of processing for low‐acid and medium‐acid canned food, although other Clostridia are more heat‐resistant.ClosureThe joint or seal which is made in attaching the cover to the glass container. Also, the type of closure, such as friction, lug, screw top, etc.CoccusShape of bacteria (plural cocci). A round / spherical cell.CodexCodex Alimentarius (Latin for “Book of Food”) is a collection of internationally recognized standards, codes of practice, guidelines and other recommendations relating to foods, food production and food safety. The texts are developed and maintained by the Codex Alimentarius Commission, a body that established by the Food and Agriculture Organization of the United Nations (FAO), and later was joined by the World Health Organization (WHO).Coliform BacteriaGroup of aerobic bacteria of which Escherichia coli is the most important member. Many coliforms are not harmful, but as they arise from faeces, they are useful as a test of contamination, particularly as a test for water pollutionColonyA microscopically visible growth of micro‐organisms on a solid culture medium.Come‐Up Time (CUT)The time which elapses between the introduction of steam into the closed retort and the time when the retort reaches the required processing temperature.Commercial SterilityThe condition achieved by application of heat which renders such food free of viable forms of micro‐organisms having public health significance, as well as any micro‐organisms of non‐health significance capable of reproducing in the food under normal non‐refrigerated conditions of storage and distribution. “Commercial sterility of equipment and containers used for aseptic processing and packaging of food means the condition achieved by application of heat, chemical sterilant(s), or other appropriate treatment which render such equipment and containers free of viable forms of micro‐organisms having public health significance, as well as any micro‐organisms of non‐health significance capable of reproducing in the food under normal non‐refrigerated conditions of storage and distribution.ConsistometerOne of the several types of instruments used to measure the consistency of foods.ContaminationEntry of undesirable organisms into some material or container.Controlled Atmosphere (CA) StorageStorage of foods in a hermetic warehouse where the concentrations of O2, CO2, and N2 are controlled at specific levels.ConvectionNatural or forced motion in a fluid induced by heat or the action of gravity.CorrosionChemical action of dissolving the surface of a metal (e.g. tin in food medium).Corrosion AcceleratorChemical species with the ability to accept electrons, which will increase the rate of a corrosion reaction.Countersink DepthThe measurement from the top edge of the double seam to the end panel adjacent to the chuck wall.Critical FactorAny property, characteristic, condition, aspect, or other parameter, variation of which may affect the scheduled process delivered and thus the commercial sterility of the product. This does not include factors which are controlled by the processor solely for purposes of product appearance, quality, and other reasons which are not of public health significance.CultureA population of micro‐organisms cultivated in a medium; pure 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 grow or survive in a medium very low in humidity or of low water activity.OsmosisA process by which molecules in a solvent tend to pass through a semi‐permeable membrane from a less concentrated solution into a more concentrated one.OxidationThe act of oxidizing which is brought about by increasing the number of positive charges on an atom or the loss of negative charges.Oxidative RancidityThe deterioration of fats and oils due to oxidation.PackageAny container or wrapping in which a consumer commodity is enclosed for delivery or display to retail purchasers.PanellingDistortion (side wall collapse) of a container caused by development of a reduced pressure (too high vacuum) inside the container.PasteurizationA heat treatment of food usually below 100°C.PathogenDisease producing micro‐organism.PathogenicCapable of producing disease.PatulinA mycotoxin.ppbParts per billion.pHA figure expressing the acidity or alkalinity of a solution on a logarithmic scale on which 7 is neutral, lower values are more acid and higher values more alkaline.Potable WaterDrinkable water / fit for human consumption.ppmParts per million.PreservationAny physical or chemical process which prevents or delays decomposition of foods.PreservativesAny substance capable of retarding or arresting food spoilage or deterioration.Primary SpoilageThat spoilage due to bacterial or chemical action of product packed within the can. See also Secondary Spoilage.Process AuthorityThe person or organization that scientifically establishes thermal processes for low‐acid canned foods or processing requirements for acidified foods.Process, ScheduledThe process selected by the processor as adequate under the conditions of manufacture for a given product to achieve commercial sterility. This process is in excess of that necessary to ensure destruction of micro‐organisms of public health significance.Process TemperatureThe calculated temperature at a particular time (process time) for which a specific can size and food product need to be heated in order to achieve commercial sterility.Process TimeThe calculated time at a particular temperature (process temperature) for which a specific can size and food product need to be heated in order to achieve commercial sterility.PSIGPounds per square inch gauge pressure.PsychrometerAn instrument for measuring the humidity (water‐vapour) content of air by means of two thermometers, one dry and one wet.PutrefactionDecomposition of proteins by micro‐organisms, producing disagreeable odours.RefractometerOptical instrument that measures the percent of soluble solids in solution by the extent to which a beam of light is bent (refracted). Soluble solids scale is based on sugar concentration in a pure sucrose solution (Brix).Relative HumidityThe ratio of actual humidity to the maximum humidity which air can retain without precipitation at a given temperature and pressure. Expressed as percent of saturation at a specified temperature.RetortAny closed vessel or other equipment used for the thermal sterilization of foods.Retort (Retortable) PouchA flexible container in which food is placed to be heated to commercial sterility in a retort or other sterilization system.Rigid ContainerA container whereby the shape or contours of the filled and sealed container are neither affected by the enclosed product nor deformed by an external mechanical pressure of up to 0.7 kg/cm² (10 psig), (i.e. normal firm finger pressure).SalmonellaA genus of bacteria that can cause infections in man that are characteristically gastrointestinal. Destroyed by adequate heating as in the canning process.SalmonellosisInfectious disease caused by bacteria of the genus Salmonella.SanitizerA chemical agent that reduces the number of microbial contaminants on food contact surfaces to safe levels from the standpoint of public health requirements.Secondary SpoilageRusted, corroded and perforated cans (from the outside towards the inside) as a result of product leaking onto them from other spoilt containers. May occur during warehousing or transport.Semi‐rigid ContainerA container whereby the shape or contours of the filled, sealed container are not affected by the enclosed product under normal atmospheric temperature and pressure but can be deformed by an external mechanical pressure of less than 0.7 kg/cm² (10 psig), (i.e. normal firm finger pressure).Shelf‐LifeThe length of time that a container, or material in a container, will maintain market acceptability under specified conditions of storage.SpoilageA process whereby food is rendered unacceptable through microbial or chemical action. See also Primary Spoilage and Secondary Spoilage.SporesSome rod forms of bacteria produce spores. In the spore state, bacteria can survive extremes of cold, heat, drying, and other unfavourable conditions for long periods of time; and when the environment is again favourable, the spores germinate, and the organisms start another cycle of growth. Growing cells are called “vegetative” cells.SpringerSwelled can with only one end remaining out; on pressing this end it will return to normal, but the other end will bulge out.Stack BurnCondition resulting from placing cased cans in piles insufficiently cooled. Food may vary from over cooked to definitely burned flavour and colour. Also, excessive corrosion of interior of container may result.StaphylococciA genus of spherical bacteria (cocci) occurring in pairs, tetrads or irregular, grape‐like clusters.Staphylococcus aureusSpecies of bacteria that are important as a cause of human infections and of food poisoning.SterileFree of living organisms.SterilizationAny process, chemical or physical, which will destroy all living organisms.Sterilization ProcessThe time‐temperature treatment necessary to render canned foods commercially sterile.Sterilization TemperatureThe temperature maintained throughout the thermal process as specified in the scheduled process.Sterilization TimeThe time that lapses between the moment a retort reaches sterilization temperature, until steam is cut off.Sterilization Value (F)The number of minutes at a reference temperature of 121.1°C (250°F) required to kill a known population of micro‐organisms with a z‐value of 10°C (18°F).Still RetortA retort for the sterilization of canned foods in batch amounts, with no agitation.StreptococciA genus of bacteria that are spherical or oval shaped and that divide in such a way that pairs or chains are formed.Superheated SteamSaturated steam that has been heated at constant pressure above its saturation temperature.Swell(1) (Noun) A container with either one or both ends bulged by moderate or severe internal pressure. (2) (Verb) To bulge out by internal pressure, as by gases caused by biological or chemical action.Swell, HardA can of food which has spoiled to the point where both ends are bulged out and show no appreciable yield to thumb pressure.Thermal ProcessThe application of heat to food, either before or after sealing in a hermetically sealed container, for a period of time and at a temperature scientifically determined to achieve a condition of commercial sterility.ThermocoupleA bi‐metallic device to measure temperatures electrically.ThermoduricMicro‐organisms that have the ability to withstand high temperatures, i.e. are highly heat resistant.ThermolabileFairly easily destroyed by heat.Tin PlateSheet steel, usually of special formula and temper, coated on both sides with a controlled thickness of pure tin.ToxinAn organic poison, a product of the growth of an organism. Some toxins are given off as waste products of a micro‐organism, and are called “exotoxins”. Others are contained within the cells, and are liberated only when the cell dies and disintegrates. These are called “endotoxins”.UHTUltra High Temperature. Term used in reference to pasteurization of commercial sterilization of food by heating it for an extremely short period, around 1–2 seconds, at a temperature exceeding 135°C (275°F).Ultraviolet IrradiationA disinfection method that uses ultraviolet (UV) light at sufficiently short wavelength to kill micro‐organisms. It destroys the nucleic acids in these organisms so that their DNA is disrupted.Vacuum PackProducts packed with little or no brine or water, which are sealed under a high mechanical vacuum, and which require maintenance of high vacuum to assure process adequacy.Vegetative CellsStage of active growth of the micro‐organism, as opposed to the bacterial spore.VentingEliminating air from a retort prior to sterilizing canned foods.VentsOpenings controlled by gate, plug, cock, or other adequate valves used for the elimination of air during the venting period.ViscosityThe internal friction or resistance to flow of a liquid. The constant ratio of shear stress to shear rate. In liquids for which this ratio is a function of stress, the term “apparent viscosity” is defined as this ratio.Water Activity (aw)A measure of water availability in food for microbial growth. The ratio of water vapour pressure of a food to the vapour pressure of pure water under identical conditions of temperature and pressure.YeastsMicro‐organisms classified in the kingdom Fungi. They are spherical or more or less elongated cells. Most yeasts break down sugars to carbon dioxide and alcohol. That process is called fermentation.Z‐valueZ‐value is a term used in thermal death time calculations. It is the temperature required for one log reduction in the D‐value for a specific bacteria.