Term
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Definition
| categories of common operating steps practiced in the food industry |
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Term
| Examples of Unit Operations |
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Definition
| Materials handling, cleaning, separation, disintegrating, pumping, forming, mixing |
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Term
| Examples of Unit operations: in Food preservation |
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Definition
| Heat exchange, evaporation, drying, packaging, non-thermal methods |
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Term
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Definition
| Prolong product quality, increase self-life, slow post-harvest physiological changes, slow microbial growth, slow enzyme activity, make some foods possible |
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Term
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Definition
| Chilling in air, indirect contact chilling, direct contact/immersion chilling |
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Term
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Definition
| still air, high velocity air (4-fold faster), fluidized bed |
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Term
| disadvantages and advantages of high-velocity air chilling |
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Definition
Disadvantages: Large temp gradient, expensive, dries out product,
Advantages: 4-fold faster |
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Term
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Definition
| high-vel air separate particles, is fast so there is no case hardening |
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Term
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Definition
Food in contact with a cooled surface, but not the refrigerant directly.
-plate heat exchanger and tubular heat exchanger |
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Term
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Definition
| Use for already packaged food. In contact with cold plates |
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Term
| Direct contact/immersion cooling |
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Definition
| Direct contact of the food with a cold refrigerant, submerge a food or spray cold liquid onto food, allow intimate contact with refrigerant |
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Term
| Direct Contact/Immersion examples |
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Definition
| Cold water spray, submerge in ice/cryogenic fluid, store on ice |
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Term
| Deterioration of foods during refrigerated storage |
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Definition
| Chill injury to fresh produce, flavor migration, nutrient loss, retrogradation of starch (synersis: water loss), oxidative rancidity of lipids, enzymatic rxns, water migration, growth of spoilage organsims |
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Term
| Microbiology and Low Temperatures |
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Definition
| Most spoilage microorganisms and pathogens dont grow at refrigeration temps. Pseudomonas is main concern |
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Term
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Definition
| pseudomonas can increase by a factor of 10 in 24 hrs at 7 C. Produces heat-stable proteases and lipases that are a concern in foods |
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Term
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Definition
- Cool to freezing point
- Super cooling (liquid water below 0C)
- Nucleation (ice crystal forms, temp increases because crystalization creates heat)
- Heat is released and local temperature increases
- Further cooling will cause more ice to grow on existing crystals
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Term
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Definition
| ice forms, free water becomes available, remaining solutes become concentrated, freezing point of unfrozen food is depressed |
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Term
| physical and chemical effects of freezing on foods |
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Definition
| water expands, dissolved solutes concentrate, freezer burn, growth of ice crystals during temp fluctuations |
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Term
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Definition
Intermittent thawing and freezing of a product, often during temperature cycling.
doesn't require a total change of ice to liquid |
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Term
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Definition
rapid freezing results in a more homogeneously dispersed ice nuclei.
Rapid freezing is essential to food quality |
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Term
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Definition
Can reduce bugs
Freezing bursts their cells and dries them out |
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