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Food Lipids: Chemistry, Nutrition, and Biotechnology

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degree of hydrogenation. Small amounts of fat (2–5%) are added to bread dough.<br />

Additional information is available in Refs. 26–28.<br />

V. SALAD OILS, MAYONNAISE AND SALAD CREAM,<br />

FRENCH DRESSINGS<br />

Salad oils, used to make mayonnaise <strong>and</strong> salad cream, should be oxidatively stable<br />

<strong>and</strong> free of solids even when stored in a refrigerator at about 4�C. Several vegetable<br />

oils may be used. Those containing linolenic acid (soybean oil, rapeseed/canola oil)<br />

are usually lightly hydrogenated to enhance oxidative stability. All oils are generally<br />

winterized to remove high-melting glycerides that would crystallize, as well also<br />

waxes present in solvent-extracted oil. The latter lead to a haze in the oil when it is<br />

cooled. Salad oils must pass a ‘‘cold test,’’ which requires that the oil remain clear<br />

for 5.5 hours at refrigeration temperature. After appropriate treatment, soybean, rapeseed/canola,<br />

corn, <strong>and</strong> sunflower oils are used to produce mayonnaise.<br />

Mayonnaise is an oil-in-water emulsion containing between 65% (legal minimum)<br />

<strong>and</strong> 80% of oil. The aqueous phase contains vinegar, citric acid, <strong>and</strong> egg yolk.<br />

This last contains lecithin, which serves as an emulsifying agent. Lemon <strong>and</strong>/or lime<br />

juice, salt, syrups, seasonings, spices, <strong>and</strong> antioxidants are optional constituents.<br />

These components may be mixed together at temperatures not exceeding 5�C (cold<br />

process) or at temperatures around 70�C (hot process). A typical mayonnaise contains<br />

vegetable oil (75–80% by weight), vinegar (9.4–10.8%), egg yolk (7.0–9.0%), <strong>and</strong><br />

small amounts of sugar, salt, mustard, <strong>and</strong> pepper (27). ‘‘Light’’ mayonnaise contains<br />

about 30–40% of oil, <strong>and</strong> in low-calorie dressings the level is 10% to less than 3%.<br />

Salad creams are similar but contain much less oil (30–40%) along with cooked<br />

starch materials, emulsifiers, <strong>and</strong> gums to provide stability <strong>and</strong> thickness. They are<br />

cheaper than mayonnaise.<br />

French dressings are temporary emulsions of oil, vinegar, or lemon juice, <strong>and</strong><br />

seasonings. Because the emulsions are not stable the dressings should be shaken<br />

before use. A nonseparating product can be made by addition of egg yolk or other<br />

emulsifying agent.<br />

According to Ref. 25, production levels in the United States during the period<br />

1993–1998 were 1.35–1.38 million pounds, comprising salad dressings <strong>and</strong> mayonnaise<br />

(0.90–0.97) <strong>and</strong> pourable dressings (0.39–0.45).<br />

Additional information is available in Refs. 8, 30, <strong>and</strong> 31.<br />

VI. CHOCOLATE AND CONFECTIONERY FATS<br />

Chocolate is an important fat-containing food based mainly, but not always entirely,<br />

on cocoa butter. Confectionery fats are materials with similar physical/functional<br />

properties to cocoa butter. Legal definitions of chocolate limit the amount of fat other<br />

than cocoa butter that may be used. The incorporation of milk fat into chocolate, the<br />

limited use of other fats, <strong>and</strong> the complete replacement of cocoa butter are discussed<br />

later in this section. The most recent book on this topic was published by Beckett<br />

(32).<br />

Annual production of cocoa beans (2.9 MMT), cocoa butter (1.5 MMT), <strong>and</strong><br />

chocolate (5 MMT) is reported to be at about the levels indicated in parentheses. A<br />

second source gives a figure of about 1.7 MMT for cocoa butter. Cocoa beans contain<br />

Copyright 2002 by Marcel Dekker, Inc. All Rights Reserved.

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