A broth dilution method was used to determine the minimal inhibitory concentration of a series of fatty acid esters of polyhydric alcohols against gram-negative and gram-positive organisms. Gram-negative organisms were not affected. Gram-positive organisms were inhibited as follows. Of the monoglycerol esters, monoglycerol laurate was the most active. Esters of polyglycerols (tri-, hexa-, and decaglycerol esters) were generally active when the fatty acid had chain lengths of 8 to 12 carbon atoms. Sucrose esters, when active, except for laurate, are more active than the free fatty acid. The spectrum of antimicrobial action of esters of polyhydric alcohols is narrower when compared with the free acids.

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Antimicrobial action of esters of polyhydric alcohols.

The industrialization of the food processing industry, including baked goods, was the result of consumers demanding high quality, convenience, longer shelf-life, easier storage conditions and high appeal to sight, touch, taste and smell. Other socioeconomic factors such as increased disposable income, need to save time and effort, access to food stuff at any time and portionability have also been factors. New trends such as more natural, healthier (saturated vs. unsaturated fats, animal vs. vegetable fats, low cholesterol), more nutritious, environmentally friendly, freshness, lower fat content, high fiber, reduced level of refined sugar, microwavable products, no bromate, clean label and low sodium are just examples of what consumers are demanding. The healthy food market products in the US are worth $30 billion and increasing by 6% annually; the reduced fat and caloric foods and beverages represent 70% of this market (Osnabrugge, 1988). To meet the above demands, the food product development and baking scientists and technologists are forced to use functional food additives such as gums, modified starches, enzyme and enzyme-treated protein, fat replacers, microglobular protein emulsifiers and many others to achieve their goals. The consumption of food additives is forecast to grow by 5.8% annually between 1988 and 1995; surfactants represent 16.6% of the total food additive consumption in 1988. In the US the consumption of surfactants was 103 million kg and expected to grow to 136 million kg (annual growth rate of 4.9%).

Emulsifiers in baking

An emulsion containing 30% fat was used to study emulsifying and foaming properties of commercial whey protein concentrates. Residual lipids, both total and phospholipids, inhibited foaming of dilute aqueous solutions of whey protein concentrates, whereas in aerated emulsions residual lipids were positively correlated with foaming. Under both test conditions the ash content was positively correlated with good and moderate foaming properties. Among the compositional factors which best predicted foaming of emulsions were sulfhydryls. Emulsions which contained insoluble whey proteins were highly stable but air incorporation was poor. When soluble whey proteins were utilized to stabilize emulsions, serum separation occurred more readily but did not correlate with good foaming properties.

Compositional Factors That Affect the Emulsifying and Foaming Properties of Whey Protein Concentrates

The effects of sorbitan tristearate (STS) and soy lecithin on blends of palm oil (PO) and olein by slow crystallization were studied. The blends of PO and olein were melted at 80C for 30 min and slowly cooled at a rate of 0.7C/min for 32 min and at 20 ± 0.1C for 48 min. Nuclear magnetic resonance was used to measure the solid fat content (SFC) development. Crystallization without emulsifier was influenced by trisaturated and disaturated triacylglycerol content of PO manifesting significant (P < 0.05) changes in SFC, crystal dispersion and viscosity, but emulsifiers in the blends disturbed these behaviors. The reaction of lecithin was very selective and was determined that at 0.03%, it generally served as a crystal promoter, while at 0.06-0.09%, it was a crystal inhibitor. Viscosity was closely related to the crystal dispersion in the liquid. The blends had low viscosity with 0.03% lecithin, while blends with high trisaturate content had high viscosity with 0.06% lecithin. STS was generally a crystal inhibitor, although at various levels, it was a crystal promoter for the middle-range saturates. Slow crystallization process of PO and olein blends with 0.03% lecithin produced homogenous crystals with low SFC and viscosity for fluidized products.

Effects of emulsifiers on crystal behavior of palm oil blends on slow crystallization

Fatty acid monoesters of propylene glycol (1,2-propanediol) are good water-in-oil emulsifiers. These esters were synthesized enzymatically to overcome the problems associated with chemical processes. APseudomonas lipase was added to reaction mixtures containing propylene glycol and various acyl donors (fatty acids, fatty acid ethyl esters, fatty acid anhydrides and triglycerides) in organic solvents, and the mixtures were shaken at 30°C. The products were analyzed by gas chromatography. The yield of monoesters was affected by the acyl donors, organic solvents, temperature, water content, pH memory and reaction time. The anhydrous (lyophilized) enzyme and fatty acid anhydrides were best for monoester production. The optimum pH ranges were 4–5 and 8–10. The yields of propylene glycol monolaurate, monomyristate, monopalmitate, monostearate and monooleate with 50 mM fatty acid anhydrides as acyl donors were 97.2, 79.6, 83.7, 89.7 and 93.4 mM, respectively; those with 50 mM fatty acids as acyl donors were 37.3, 28.7, 28.7, 35.3 and 36.2 mM, respectively. The yields of propylene glycol monopalmitate, monostearate and monooleate with 50 mM triglycerides as acyl donors were 87.4, 65.1 and 83.2 mM, respectively.

Production of propylene glycol fatty acid monoesters by lipase-catalyzed reactions in organic solvents

General classifications of food emulsifiers are presented, and their functions are discussed. Examples of many food products are given, and recommended emulsifier usage levels are presented. Some of the food applications cited include: cakes, icings, toppings, bread, sweet goods, frozen desserts, coffee whiteners, peanut butter, margarine and confectionery coatings.

Nat H. Nash

Papers

Food emulsifiers—Science and art