Essentials of Thermal Processing. Gary Tucker S.

      The authors during a practical training course session in Cape Town.

Glossary of Terms

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