Measuring flavor deterioration of fats,oils, dried emulsions and foods

In fats, oils, and simple systems such as model dried emulsions, conventional measurements such as peroxide values and oxygen absorption measurements usually give a valid measure of sample flavor. In real food systems, this is often not the case. Measures of volatile (CO₂, pentane) and nonvolatile (anisidine reactive compounds) peroxide decomposition products often give a better picture of the organoleptic status of a sample. Unusually large amounts of CO₂ are liberated when fats and oils oxidize in the presence of proteins. The implications of this phenomenon are discussed. Presented at the AOCS Meeting, New Orleans, April 1976.     

Phytosterols and human lipid metabolism: efficacy,safety, and novel foods

Plant sterols have been known for several decades to cause reductions in plasma cholesterol concentrations. These plant materials have been granted a conditional health claim in the United States regarding their effects in the prevention of cardiovascular disease and are being sold in functional foods in several countries in Europe as well as in the United States and Australia. It is generally suggested that daily consumption of ∼2 g of plant sterols can lower cholesterol concentrations as part of a dietary prevention strategy. However, phytosterols have been added and tested for their cholesterol-lowering effects mainly in spreads. Consumption of these high-fat foods seemingly flies in the face of current recommendations for the promotion of heart health, which suggest lowering total fat and energy intake to maintain weight. Hence, new food formulations are being evaluated using phytosterols incorporated into low-fat and reduced-fat food items. The purpose of this review is to examine the cholesterol-lowering efficacy of plant sterols, focusing on novel food applications, their mechanism of action, and safety. These novel food formulations include new solubilization processes that lead to improved uses for plant sterols, as well as new foods into which phytosterols have been incorporated, such as breads, cereals, and beef. Such new foods, and formulations should pave the way for greater use of phytosterols in heart health promotion, increasing the longer-term potential for the creation of innovative functional foods containing plant sterols and their derivatives.     

Some important fermented foods of Mid-Asia,the Middle East,and Africa

Other speakers in this Symposium discussed fermented foods of China, Japan, and Southeast Asia; I will describe several other fermented foods that are very important in Mid-Asia, the Middle East, and Africa. These fermentations, unlike those of the Orient, use bacteria and yeasts instead of filamentous fungi. They are acid products prepared from cereals traditionally grown in the areas, notably sorghum, millet, maize, and wheat. Since African, Middle Eastern, and Mid-Asian fermented foods are often supplemented with milk or legumes, the final protein content may be rather good. For example, bouza and ogi have a protein content of 11 to 13% on a dry weight basis, while in kishk the protein content is about 23.5%. In the Indian food idli, the protein average content is 15.3%. Advantages of acid fermented food products are:

? Preservation of the fermented product because of the organic acids produced. These acid products are sometimes dried to give even longer keeping times.

? They are high in fiber content.

? Because some are dried, they may be transported easily from one place to another.

? They probably have enhanced nutritional value because of the vitamins formed during production.

? They are foods used for centuries and therefore culturally acceptable.

? Unlike some of the other fermented foods discussed, they are used as main course dishes rather than flavoring agents.

An example of a Mideast food prepared by lactic acid bacteria is tarhana of Turkey, which consists of parboiled wheat meal, yogurt, and added vegetables which are then allowed to ferment and then sun dried. In Central and South Africa, kaffir beer (Bantu beer) is made by malting maize or sorghum, fermenting with lactic acid bacteria to give a low pH, and then finally fermenting with a yeast. The protein content ranges from 8.5 to 11.9%. A second commercially produced product is mahewu (magou) prepared by the natural fermentation of maize to produce an acid mash which is then dried. This food has a content of 7–9% protein.     

Exercise and functional foods

Appropriate nutrition is an essential prerequisite for effective improvement of athletic performance, conditioning, recovery from fatigue after exercise, and avoidance of injury. Nutritional supplements containing carbohydrates, proteins, vitamins, and minerals have been widely used in various sporting fields to provide a boost to the recommended daily allowance. In addition, several natural food components have been found to show physiological effects, and some of them are considered to be useful for promoting exercise performance or for prevention of injury. However, these foods should only be used when there is clear scientific evidence and with understanding of the physiological changes caused by exercise. This article describes various "functional foods" that have been reported to be effective for improving exercise performance or health promotion, along with the relevant physiological changes that occur during exercise.     

Phospholipid content of foods

The content of total lipids and total and component phospholipids in ca. 140 foods was compiled in response to frequent requests for data by researchers in nutrition and medicine, and to fill the appar-ent need for a reliable up-to-date tabulation of recent data. Eggs, organ meats, lean meats, fish, shellfish, cereal grains and oilseeds are good sources of phospholipids, especially the choline phosphatides: phosphatidylcholine, sphingomyelin and lysophosphatidylcholine. Leafy vegetables, fruiting parts, roots and tubers are, with few ex-ceptions, relatively poor dietary sources of total lipids and phospho-lipids. Foods or tissues in which the phospholipids perform similar functions also have similar relative phospholipid distributions. The data were tabulated by food group in separate tables with appropri-ate discussion. The use of conversion factors for calculating the total and individual phospholipids, sources of error, and research needs are discussed.     

Development of new,nonabsorbable polymeric antioxidants for use in foods

The metabolic fate of a new, oil soluble antioxidant, selected from a series representing a unique class of phenolic polymers, is discussed together with its activity in unsaturated vegetable oils as compared to butylated hydroxytoluene, butylated hydroxyanisole, and tertiary butylhydroquinone (TBHQ). Using gel permeation chromatography,¹⁴C-radiolabeled polymer was isolated into discrete mol wt fractions and these administered as single oral doses to rats. Results indicate that while monomeric¹⁴C-TBHQ with a mol wt of 166 shows a total absorption of 88.3% of the administered dose, the absorption of polymeric antioxidant is vastly reduced with increasing mol wt; i.e., mol wt 760: 1.5%, mol wt 7300:0.44%, and mol wt 67,000: 0.34%. Functionality tests using the active oxygen method indicate that by increasing the phenolic constituents in the polymer composition the antioxidant activity can surpass that of certain traditional, monomeric food grade antioxidants. Stability tests using thermogravimetric analysis indicate the polymeric antioxidants are not depolymerized in the presence of air at temperatures up to 300 C. Further, the polymers are nonvolatile and under deep frying conditions result in nearly quantitative carry-through of antioxidant in that portion of oil absorbed by the food; a monomeric food grade antioxidant (TBHQ) shows losses due to volatilization. Presented at the AOCS Meeting, Dallas, April 1975.     

Iron, zinc and copper content of foods commonly consumed in Mexico

Nutrient composition in foods is necessary for the determination of nutrient intake. Food composition tables used for dietary studies in Mexico do not have information of zinc, iron and copper; when present the values have been extrapolated from laboratory analysis carried out with foods in other countries and regions of the world. In this study zinc, iron, and copper content of 104 plant foods and 32 animal foods was determined. The procedure used was atomic absorption spectrophotometry for the minerals. Foods were grouped into cereals, vegetables, fruits, legumes and animal foods. Zinc content ranged from 0.018 mg/100 g for strawberry to 9.193 mg/100 g for beef. Iron content ranged from 0.113 mg/100 g for yogurt to 19.82 mg/100 g for a commercial cereal which had minerals added during processing. In some foods copper was not found and the highest content was 3.371 mg/100 g in beef liver. This study has provided information on zinc, iron and copper content of the most commonly consumed foods in Mexico.     

Toward a simple,generic, and rapid simulation of the drying of solid foods

Abstract

In order to simulate the drying of foods, calculations based on finite differences, elements, or volumes are extremely time-consuming, particularly when embedded in an optimization procedure. Such models, involving coupled heat and mass transfers and nonlinear properties and boundaries, give rise to slow simulations. This paper proposes a new method concerning the slab, cylindrical, and spherical geometries. This method gives results equivalent to those of the finite volume method but is more rapid by an order of magnitude. The method is based on an optimized 3-compartment model whose parameters are linked to physically meaningful food properties.     

Nutritional quality in formulated foods

With advances in food technology, fortification of foods for proper nutrition is becoming more complex. Eating patterns are changing; snack foods and formulated products are becoming a larger part of the diet. An added nutrient must be regarded as a food additive and its safety must be established. Meat analogs and meal replacements involve special problems. Additional analytical methods are needed. The optimum quantity of added nutrient must be carefully determined and controlled. Programs must be devised to inform consumers about food quality and safety. Presented at the AOCS Meeting, Atlantic City, N.J., October 1971.     

Agitated thin-film drying of foods

Agitated thin-film drying (ATFD) has been proposed for efficient and mild drying of viscous liquid foods, pastes or pureed foods. We report a study on the influence of product and process parameters on ATFD. During ATFD of spinach leaf slurries, the wall temperature mainly affected the specific evaporation rate, while the absolute evaporation rate was proportional to the feed rate. The fact that blade rotation speed had limited effect on the drying rate suggested that the process is limited by heat transfer through the wall. ATFD is especially suited for slurries that show relatively limited sticky behavior during drying and liquid–solid phase transition with corresponding brittle viscoelastic behavior. This was demonstrated by drying juices from tomato and bell pepper, giving poor results, and by drying solutions from whey protein isolate (WPI) and sucrose, which could be successfully dried.     

Soybean proteins in prudent-diet foods

A review is presented on soybean proteins and their health, nutritional, convenience, stability, and economic attributes that justify usage in prudent-diet foods. The concept of these foods is discussed with consideration the contributions of soybean proteins to caloric energy, ratios of polyunsaturated to saturated fatty acid, ratios of polyunsaturated to saturated fatty acids, cholesterol, sodium ion, and levels of sugars. Soybean proteins provide technologists with a cheap, functional protein source for developing meat analogs. Inherent soybean flavors are considered the major unstabilizing problem in prudendiet foods. The energy requirement for producing one pound of meat analog is estimated at 12,300 BTU; soy flour used in it requires only 330 BTU, while cooked meat requires approximately 52,250 BTU per pound.