Roasted Soybean Flour Research Articles

The Science of Soy: What Do We Really Know?

A stroll through nearly any American grocery store or pharmacy yields ample proof of the soybean’s increasing role in the U.S. diet. Food packaging offers statements about products’ soy content and the purported associated health benefits. Products such as tofu, soy milk, soy-based infant formula, and meatless “texturized vegetable protein” burgers are widely available. Shelves of dietary supplements and nutraceuticals are stocked with isoflavones, naturally occurring estrogenic compounds found in soy. The general impression is one of certainty that both soy and soy isoflavones deliver many health benefits, including prevention of cardiovascular disease, cancer, and osteoporosis, as well as treatment of menopausal symptoms. The science is less absolute, however, and still evolving. Soy provides a complete source of dietary protein, meaning that, unlike most plant proteins, it contains all the essential amino acids. According to the American Soybean Association, 3.14 billion bushels (85.5 million metric tons) of soybeans were harvested in the United States in 2004. Approximately half of the harvest was exported, and most of the remainder was crushed to produce oil and protein meal for domestic use. An April 2006 report from the USDA Economic Research Service indicates that only a small amount of whole soybeans are used to produce soy foods, and just 2% of soy protein meal is used for human consumption; the rest is used for animal feed. The Soyfoods Association of North America reports that U.S. sales of soy foods reached $3.9 billion in 2003, continuing an 11-year trend of 15% average annual increases. According to the United Soybean Board’s 2004–2005 Consumer Attitudes About Nutrition report, 25% of Americans consume soy foods or beverages at least once per week, and 74% view soy products as healthy. Nevertheless, Americans as a whole still consume very little soy protein. Based on 2003 data from the UN Food and Agriculture Organization, per-capita soy protein consumption is less than 1 gram (g) per day in most European and North American countries, although certain subpopulations such as vegetarians, Asian immigrants, and infants fed soy-based formula consume more. The Japanese, on the other hand, consume an average 8.7 g of soy protein per day; Koreans, 6.2–9.6 g; Indonesians, 7.4 g; and the Chinese, 3.4 g. Traditional soy foods include tofu, which is produced by pureeing cooked soybeans and precipitating the solids, and miso and tempeh, which are made by fermenting soybeans with grains. “Second generation” soy products involve chemical extractions and other processing, and include soy protein isolate and soy flour. These products become primary ingredients in items such as meatless burgers, dietary protein supplements, and infant formula, and are also used as nonnutritive additives to improve the characteristics of processed foods.

Ability of a “very low-cost extruder” to produce instant infant flours at a small scale in Vietnam

Extrusion cooking is a useful process for the production of instant infant flours, as it allows gelatinisation and partial dextrinisation of starch, as well as reduction of the activity of some antinutritional factors. But existing extrusion equipment is not suited to the context of developing countries as it requires considerable financial investment and the production capacity (minimum 300 kg/h) is too high. The aim of our study was to improve traditional extruders with low production capacity (about 30 kg/h) manufactured in Vietnam and to test their performance in the production of infant flours. Several blends made with rice, sesame and/or soybean have been extruded with the modified equipment that we name “very low-cost extruder”. In the case of blends containing soybean, starch gelatinisation was not complete, and decreased with an increase in the lipid content of the blend. The rate of trypsin inhibitor destruction evolved in a similar way. Adding water before extrusion, or extruding the blends twice was not effective in increasing the rates of starch gelatinisation or trypsin inhibitor destruction. However, the “very low-cost extruder” proved its ability to process the rice–sesame blend that had a lipid content of less than 6 g/100 g DM, and low initial water content [around 10%, wet basis (wb)]. In this case, extrusion led to total starch gelatinisation and the extent of starch dextrinisation, which was measured by comparing the viscosity of gruels prepared from crude and corresponding extruded blends, was sufficient to prepare gruels with substantially increased energy density. With the addition of roasted soybean flour, sugar, milk powder, vitamins and minerals, this blend could provide a nutritious instant flour usable as complementary food for infants and young children.

Physicochemical properties and nutritional traits of millet-based weaning food suitable for infants of the Kumaon hills, Northern India.

A weaning food based on malted foxtail millet flour (30%), malted barnyard millet flour (30%), roasted soybean flour (25%) and skim milk powder (15%) was prepared. The mix contained 18.37 g protein and 398 kcal energy per 100g. The nutrient composition of this unfortified weaning (UW) mix met the Prevention of Food Adulteration (PFA) standards, except in total ash. In order to meet the minor constituent requirements, the UW mix was fortified. The fortified weaning (FW) mix met PFA standards for various nutrients. The protein efficiency ratio of the UW mix was 2.25 against a casein control, for which a value of 2.50 was recorded. The nutrient composition, viscosity and sensory quality of the UW mix was compared with the marketed weaning mix, commercial infant formula. The viscosity of UW gruel was much lower (20 centipoise (cps)) than that of marketed weaning mix (7400 cps). The high alpha-amylase activity of 661 units in the UW mix was responsible for its low viscosity. The sensory quality of UW mix and marketed weaning mix did not differ significantly (P = 0.05). Both of the gruels were liked moderately on the Hedonic Scale. The UW gruel met the acceptability criteria for weaning food. It could be stored in plastic airtight containers at room temperature for 4 months without any changes in sensory quality.

Effect of soyflour supplementation on the quality of cooked noodles

SummaryNoodles were prepared from semolina of durum and aestivum wheats and flour of aestivum with or without 10% of different types of full fat soyflour (i.e. enzyme active, conventional and roasted soyflour) and defatted soyflour. Cooked weight and water absorption of noodles increased with the increase in cooking time but decreased with addition of soy solids. The latter also increased losses of total solids and deceased losses of nitrogen into the cooking water. Sensory evaluation of noodles indicated that the product made from durum semolina containing 10% of defatted soyflour was as good as that from durum semolina alone.

Fungal Contamination of Cereals and Their Products, and Aflatoxin Productivity of Aspergillus flavus Isolated

In order to obtain a breaf information albout extent of Contamination of foodstuffs by fungi especially by Aspergillus flavus which is known to produce aflatoxin, fungal and bacterial examination of flours and cereals on sale, such as buckwheat flour, wheat flour, roasted soybean flour, soybean and peanut, were carried out. Isolated fungi were identlfied and aflatoxin productivity of A. flavus found among them was studied.Test material was suspended and homogenized in phosphate buffer saline and mix-cultured in potato dextrose agar containing chloramphenicol. After 7 days incubation at 27°C, number of the colonies of fungi and yeasts developed were counted. Fungi and yeasts were found from 77% of the materials tested over all; and 100, 90, 45.5, 78.9 and 73.3% from buckwheat flour, wheat flour, roasted seybean flour, soybean and peanut, respectively. Number of fungi and yeasts in average in each foodstuffs tested were as follows: 23, 000/g in buckwheat flour, 240/g in wheat flour, 90/g in roasted soybean flour, 130/g in soybean and 280/g in raw non-shelled peanut.Bacterial counts made on plain agar were as follows: 170, 000/g in buckwheat flour, 860/g in wheat flour, 130/g in roasted soylbean flour, 400/g in soybean and 540/g in raw nonshelled peanut. Degree of fungal contamination did not correlate with that of bacterial contamination. Moisture contents of the test materials also showed no correlation with degree of fungal or bacterial contamination.The most prevaling genus among isolates of fungi was Penicillum (43.8%) and next one was Aspergillus (24.0%). In addition to them, Cladosporium (6.3%), Rhizopus (3.1%), Cephalosporium (2.1%), Scopulariopsis (2.1%), Epicoccum (2.1%), Paecilomyces (2.1%), Mortierella (1.0%), Gonatobotrys (1.0%), Botrytis (1.0%), Monilia (1.0%) and Mucor (1.0%) were also isolated.Among 23 strains of the isolates of Aspergillus, 10 were identified as A. flavus, of which 7 were isolated from buckwheat flour and the others were from wheat flour. Five strains of them were proved to elaborate aflatoxin B1 and/or B2 in vitro. Most of them produced the toxin only in a small amount, but one strain which was isolated from wheat flour produced toxin B1 in fairly large amount. It was estimated to be 23.2mg/kg of the mold rice medium by fluorodensitometric method. Toxicity of this toxin was tested by chicken embryo method. The value of LD50 was 0.125μg/Egg.Aflatoxin itself was not detected directly in the material from which A. flavus was isolated.