Term
| Purpose of removing water |
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Definition
| Slow spoilage (Aw<.6), reduce bulk/weight/volume, control texture, make new products (syrup) |
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Term
| Concentration and evaporation |
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Definition
| Partial removal of water from foods to increase its total solids content |
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Term
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Definition
| extensive approach to moisture removal in which product moisture is reduced to a few percent |
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Term
| Methods of concentration and evaporation |
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Definition
| Open kettles, vacuum evaporator, freeze concentration |
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Term
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Definition
| Liquid to gas fast, increase surface area, lose lots of volatile compounds |
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Term
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Definition
| concentration of a product at the freezing point by ice crystal formation and separation. Retain more flavor |
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Term
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Definition
| compounds that due to their high vapor pressure and low water solubility enter the gaseous phase. |
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Term
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Definition
| sun/oven drying, forced-air drying, spray drying, roller/drum drying, tunnel drying, freeze drying |
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Term
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Definition
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Term
| forced-air drying examples |
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Definition
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Term
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Definition
| turn liquid into mist in a container with hot air. Eggs |
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Term
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Definition
| scrape thin layer off of hot drum. mashed potatos, fruit? |
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Term
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Definition
| conveyer belt oven. pizza, snacks, cereal |
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Term
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Definition
| sublimation of solid ice to vapor under vacuum. Expensive, but retains character of original food and no volatiles lost. strawberries |
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Term
| Factors that affect drying: product |
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Definition
| composition (water, sugar, Aw), amount of product, surface area/vol ratio, product porosity, pre-treatments (blanching) |
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Term
| Factors that affect drying: Drier |
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Definition
| type of drier, temperature, humidity, pressure, air flow, air volume |
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Term
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Definition
| Falling rate period (water to surface- diffusion is rate-limiting) --> Critical Moisture Content (reducing rate) --> Constant Rate Period (water evap from surface) |
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Term
| Physical effects on foods and drying |
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Definition
| Loss of structural water, loss of water btw and within cells, concentration of solutes, Case hardening |
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Term
| Loss of water btw and within cells: results in? |
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Definition
| shrinkage, cell collapse, surface cracking. Not reversible, enzymatic browning |
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Term
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Definition
| Formation of a hard outer layer that traps water inside the product (raisin) |
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Term
| Raisin Manufacturing process |
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Definition
| Grow grapes--> Harvest --> dry --> equilibration--> Sorting and washing --> packaging |
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Term
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Definition
| Usually in rows and on trellises |
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Term
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Definition
| spread on sheets for 2-3 weeks. Moisture content drops from 80% to 15%. Sun heats soil and direct sun light. |
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Term
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Definition
| rolled up for several days to soften shell |
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Term
| Why are raisins brown or yellow? |
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Definition
| Brown raisins because of enzymatic browning. Yellow because sulfite inhibitor is added (can aggravate asthma) |
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