Bibliography. Current world literature. Micronutrients, nutraceutics and functional foods.
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OBJECTIVES: Probiotic and prebiotic products manufactured in South Africa were identified and health and content claims stated on the labels were evaluated according to available scientific evidence, the proposed South African regulations in the Foodstuffs, Cosmetics and Disinfectants Act (Act No. 54 of 1972, www.doh.gov.za), and microbial assessment. RESULTS: The range of products identified included probiotic- and/or prebiotic-containing supplements (capsules), food items fortified with probiotics and/or prebiotics, and fermented food containing probiotics, e.g. dairy products. Most of the health-related claims on the labels of the identified products do not comply with proposed South African regulations. However, results also indicate that the proposed South African regulations should be reconsidered to include an additional 5 claims, for which scientifically sound evidence is available. The claims regarding probiotic strains, viable cell numbers, prebiotic type and concentration stated on the labels of the products are mostly in line with the proposed South African regulations. The actual viable cell content of 3 out of 5 probiotic supplements readily available on the South African market did not comply with the content claim stated on the label. However, this problem did not seem to affect the inhibitory activity of the probiotic strains against indicator strains isolated from faeces of patients diagnosed with AIDS. To validate this finding in vivo assessments should be implemented before considering the need to include a wider range of prescribed viable cell numbers in the proposed South African regulations. CONCLUSIONS: The proposed South African regulations regarding probiotic- and prebiotic-containing products should be revised based on the results of this research, and the manufacturers of these products should be held responsible for providing the consumer with scientifically sound and legally correct information.
Kava (Piper methysticum) dietary products have been sold worldwide for treatment of nervous anxiety, tension, and restlessness. Recent reports showed potential association of kava usage and liver injuries. This study was conducted to develop simple and reliable methodologies for the extraction and determination of 6 major kavalactones: (+)-methysticin, (+)-dihydromethysticin, (+)-kavain, (+)-dihydrokavain, yangonin, and desmethoxyyangonin. Ultrasonic extraction techniques and isocratic reversed-phase liquid chromatography (LC) were optimized for different types of samples, including capsules containing kava root extract or root powder, raw root material, tea bags, and snack bar. A suitable internal standard, 5,7-dihydroxyflavone, was used for LC calibration. Kavalactones were completely separated in 30 min using a Luna C18-2 column at 60 degrees C with an isocratic mobile phase consisting of 2-propanol-acetonitrile-water-acetic acid (16 + 16 + 68 + 0.1, v/v/v/v). Within-laboratory, intraday, and interday method variation (% relative standard deviation) for most samples extracted by methanol or methanol-water mixture were <5%. Lower levels of kavalactone contents and higher variations were observed for tea bags from water extraction or infusion as compared to methanol extraction. Labeling information of tea bags based on methanol extraction could be misleading to consumers. Analytical recoveries of snack bar fortified at 10 and 20 microg/g were >84% with RSD values <8%. Methods developed in this study offer a simple and reproducible means for analysis of kavalactones in various matrixes of dietary products.
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The effects of maturity degree and culture type on oligosaccharide content were studied in soybean seed, a rich source of non-digestible galactooligosaccharides (GOS). Therefore, two commercial cultivars of yellow soybeans (ripe seeds) and two of green soybeans (unripe seeds) were chosen. One yellow and one green soybean seed were from intensive culture, while one yellow and one green soybean seed were biologically grown. Low molecular weight carbohydrates (LMWC) in soybean seeds were extracted with 85% ethanol and determined spectrophotometrically and by high performance liquid chromatography. LWC in soybean seeds were mainly: stachyose, raffinose and sucrose. Oligosaccharide content was not affected significantly, either by biological or intensive culture technique. On the contrary, significant differences in GOS content were found depending on ripeness degree of soybean seeds. Ripe yellow soybean seeds showed a higher oligosaccharide content (1.84-1.95%), than unripe green seeds (1.43-1.61%). Other LMWC content was also affected by ripeness degree, thus making that the relative percentage of GOS was higher in immature (47-53%) than in matured soybean seeds (21-34%). Moreover, in order to purify soybean GOS, biologically grown yellow soybean seeds with a higher GOS content were selected and a previously reported method was followed. Although the GOS containing fraction was enriched, the yield obtained was low and an effective purification was not achieved. According to these results, yellow soybean seeds seem to be a good source of GOS but, in order to improve their purification, simple methods must be further developed and evaluated.
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Many functional requirements are met by the use of simple and complex carbohydrates in food. Carbohydrates offer a wide range of rheological and other properties, including solubility, cryoprotection, sweetening effect, hygroscopicity, crystallization inhibition, flavor encapsulation, and coating ability. These properties are based on chemical structure and interactions with other molecules through hydrogen bonding, ionic effect, and the formation of complexes with lipids and proteins. The ability to understand these properties directly affects the development of food products and processes. Thus, the functionality of carbohydrates in foods integrates precise knowledge of chemical structure and behavior with practical applications in the development and preparation of foods.
Nutraceuticals are naturally occurring/derived bioactive compounds that are reported to have health benefits. The delivery systems for nutraceuticals are foods (functional foods), supplements, or both. Drugs are designed to have medicinal properties for the prevention and treatment of identified diseases or signs and symptoms of disease. Counterfeit drugs contain either placebo, materials not identified in the labeling or substandard or impure materials, which may produce untoward pharmacological or toxicological effects. In addition, the consumer has the right to microbiological safety and prevention from adverse exposure to hazardous chemical(s), and other adverse compounds. Nutraceutical/drug delivery systems are viewed as approaches to (1) enhanced consumer health, (2) decreased healthcare costs, and (3) enhanced economic development. Therefore, the nutra/pharma/ceutical industry is reliant upon a strong underpinning of diversified research that addresses safety and assures chemical and biological efficacy. Significant safety through traceability can be assured by the coupling of the technologies of (a) global positioning (GPS); (b) bar/chip coding; and (c) hazard analysis critical control point (HACCP) management, coupled to rapid nanotechnology marker assays now under development.
For studying the contents of dietary fiber in general foods and functional foods, a enzymatic-gravimetric method recommended by AOAC was established in our laboratory. The method for the determination of total, soluble and insoluble dietary fiber in foods and functional foods could be used for many other kind of foods. The relative standard deviations (RSD) of reproducibility between-run and within-run were 2.04%-7.85%, 3.42%-55.23% respectively. The repeatability of the methods was good, and the methods are suitable for many foods.
Cottonseeds contain protein with desirable food functional and nutritional properties. Storage globulins make up most of the protein stored in cottonseed and can be separated into five fractions by gel filtration chromatography. Each fraction is distinguishable from the other by its amino acid and polyacrylamide gel electrophoretic properties. Proteins of cottonseed contribute greatly to the functional properties of emulsions, co-isolates, and texturized derivatives. For example, increasing the amount of high protein cottonseed flour in wheat suspensions from 2% to 10% improved the capacity (54-97 ml of oil) and viscosity (5,000-100,000+ cps) of emulsions. The 10% suspension formed emulsions with increasing oil capacity (84-100 ml) and viscosity (28,000-100,000+ cps) as the pH was adjusted from 4.5 to 9.5. Consistencies of the products ranged from that of salad dressing (low percent suspensions, or acid pH) to that of mayonnaise (high percent, or basic pH). These data were utilized to derive a multiple regression model to predict optimum use of cottonseed proteins in emulsions of varying consistencies. A coprecipitated isolate containing greater than 94% protein was prepared from a blend of cottonseed and peanut flours. Amino acid content of the co-isolate reflected that of the protein in the two flours of the composite. The co-isolate has lower gossypol level and improved color and functional properties than a cottonseed protein isolate. Storage protein isolate of cottonseed suspended in aqueous solution and heated with constant stirring forms a texturized product; the quality of the product depends on heat, pH, salt, and the quantity of nonstorage proteins. Protein and amino acid content of meat products were improved by the addition of the texturized protein of cottonseed.
Fresh and sun-dried dates of three native varieties from Oman, namely, Fard, Khasab, and Khalas, were examined for their antioxidant activity and total contents of anthocyanins, carotenoids, and phenolics, as well as free and bound phenolic acids. All results are expressed as mean value +/- standard deviation (n = 3) on a fresh weight basis. Fresh date varieties were found to be a good source of antioxidants (11687-20604 micromol of Trolox equiv/g), total contents of anthocyanins (0.24-1.52 mg of cyanidin 3-glucoside equiv/100 g), carotenoids (1.31-3.03 mg/100 g), phenolics (134-280 mg of ferulic acid equiv/100 g), free phenolic acids (2.61-12.27 mg/100 g), and bound phenolic acids (6.84-30.25 mg/100 g). A significant (p < 0.05) amount of antioxidants and carotenoids was lost after sun-drying of dates, whereas the total content of phenolics and free and bound phenolic acids increased significantly (p < 0.05). Anthocyanins were detected only in fresh dates. Date varieties had different levels and patterns of phenolic acids. Four free phenolic acids (protocatechuic acid, vanillic acid, syringic acid, and ferulic acid) and nine bound phenolic acids (gallic acid, protocatechuic acid, p-hydroxybenzoic acid, vanillic acid, caffeic acid, syringic acid, p-coumaric acid, ferulic acid, and o-coumaric acid) were tentatively identified. Of the date varieties studied, Khalas, which is considered to be premium quality, had higher antioxidant activity, total carotenoids, and bound phenolic acids than other varieties. These results suggest that all date varieties serve as a good source of natural antioxidants and could potentially be considered as a functional food or functional food ingredient, although some of their antioxidant constituents are lost during sun-drying.
The search for functional foods or functional food ingredients, i.e. foods or food ingredients that can enhance health, is beyond any doubt one of the leading trends in today's food industry. In this context, probiotics, i.e. living microbial food supplements, and prebiotics, i.e. non-digestible food ingredients, receive much attention. Both popular concepts target the gastrointestinal microbiota. While in the Western world, intake of probiotics has been recommended for long, prebiotics in general, and non-digestible oligosaccharides in particular, have only recently received attention. This review deals with production and characterization of non-digestible oligosaccharides and focuses on their role in promoting health and treating diseases. Attention is paid to the effects of non-digestible oligosaccharides on constipation, mineral absorption, lipid metabolism, cancer prevention, hepatic encephalopathy, glycemia/insulinemia, and immunomodulation.
The small intestinal epithelium plays a crucial role in the digestion/modification of food components, absorption of nutrients and recognition of food-derived signals. It also acts as a barrier against unfavourable materials in food. These intestinal functions may be influenced by food substances. In this paper, the effects of various food substances on the intestinal functions, particularly the absorption functions, are discussed. A new assay method, using a monolayer culture system of human intestinal epithelial cells, is applied to examine food-derived substances which could modulate the tight junction (TJ). Capsianoside, a diterpene glycoside from sweet pepper, was isolated and identified as one of the TJ-modulating substances. Those substances can be expected to facilitate the paracellular absorption of small molecular functional substances such as bioactive oligopeptides. The use of a human intestinal cell culture system also enabled us to make a simple screen test for food substances which affect the intestinal transporter functions. Substances which could suppress the activity of intestinal glucose transporters, for example, can be expected to reduce the dietary glucose uptake in the intestinal epithelium and control the blood glucose level. Polyphenolic compounds from plants, including green tea, were found to have such activity. Modulation of the brush border enzymes by food substances is also discussed.