Effect of heat processing of spices on the concentrations of their bioactive principles: Turmeric (Curcuma longa), red pepper (Capsicum annuum) and black pepper (Piper nigrum).

Studies were made to examine the loss of curcumin, capsaicin and piperine, the active principles of turmeric (Curcuma longa), red pepper (Capsicum annuum) and black pepper (Piper nigrum), respectively, as a result of subjecting the spices to domestic cooking processes. This involved heat treatment of each of these spices by: (i) boiling for 10 min, (ii) boiling for 20 min and (iii) pressure cooking for 10 min. Quantitation of the spice principles in the organic solvent extracts of the freeze-dried cooked spice samples was made with an appropriate HPLC method. Significant loss of spice active principles was observed when the spices were subjected to heat processing. Curcumin loss from heat processing of turmeric was 27–53%, with maximum loss in pressure cooking for 10 min. Curcumin loss from turmeric was similar even in the presence of red gram. In the presence of tamarind, the loss of Curcumin from turmeric was 12–30%. Capsaicin losses from red pepper ranged from 18% to 36%, with maximum loss observed in pressure cooking. Presence of either red gram or tamarind or both did not influence the loss of capsaicin. Piperine losses from black pepper ranged from 16% to 34%, with maximum loss observed in pressure cooking. The loss was somewhat lower in the presence of red gram. The results of this investigation indicated diminished availability of spice active principles from cooked foods when the food ingredients have been subjected to either boiling or pressure cooking for few minutes

Bioaccessibility of Polyphenols from Wheat (<i>Triticum aestivum</i>), Sorghum (<i>Sorghum bicolor</i>), Green Gram (<i>Vigna radiata</i>), and Chickpea (<i>Cicer arietinum</i>) as Influenced by Domestic Food Processing

Cereals (wheat and sorghum) and legumes (green gram and chickpea) commonly consumed in Asia and Africa were evaluated for polyphenolic content. Bioaccessibility of polyphenols from these grains as influenced by domestic processing was also estimated. Total polyphenol content of wheat and sorghum was 1.20 and 1.12 mg/g respectively, which was increased by 49% and 20% respectively, on roasting. In contrast, a significant reduction of the same was observed in both the cereals after pressure-cooking, open-pan boiling, and microwave heating. Total flavonoids, which was 0.89 mg/g in native sorghum, reduced drastically after processing. Tannin content of both the cereals significantly increased on sprouting as well as roasting. Total polyphenol content reduced by 31% on sprouting but increased to 24% on roasting in green gram. Pressure-cooking (53%), open-pan boiling (64%), and microwave heating (>2-fold increase) significantly increased total polyphenol content in chickpea, while drastic reduction was observed in the total flavonoid content. Bioaccessible total polyphenols from these grains were in the following order: green gram > chickpea > wheat > sorghum. Domestic processing of these grains had minimal/no effect on the bioaccessible total flavonoid content. Not all the phenolic compounds present in them were bioaccessible. Concentration of bioaccessible phenolic compounds increased especially on sprouting and roasting of these grains, except chickpea, where sprouting significantly reduced the same (476 to 264 μg/g). Microwave heating significantly enhanced the concentration of bioaccessible polyphenols especially from chickpea. Thus, sprouting and roasting provided more bioaccessible polyphenols from the cereals and legumes studied

Ameliorative Influence of Dietary Fenugreek (<i>Trigonella foenum-graecum</i>) Seeds and Onion (<i>Allium cepa</i>) on Eye Lens Abnormalities via Modulation of Crystallin Proteins and Polyol Pathway in Experimental Diabetes

<p><i>Purpose and Methods</i>: Hyperglycemia-induced osmotic and oxidative stress is thought to be involved in the pathogenesis of diabetes-related secondary complications including cataract. In continuation of our previous observation of the ameliorative influence of these spices on hyperglycemia, attendant metabolic abnormalities, and oxidative stress in tissues of diabetic rats, the beneficial influence of dietary (10%) fenugreek seeds, (3%) onion, or their combination was investigated on diabetes-induced alteration in the eye lens of streptozotocin-induced diabetic rats.</p> <p><i>Results</i>: Animals maintained on these spices showed significantly countered oxidative stress markers (reactive oxygen species, lipid peroxidation and protein carbonyl), advanced glycation end products, and expression of their receptor in the eye lens. Increased activity of polyol pathway enzymes, their protein, and mRNA expression was significantly countered in the cataractogenic lens as a result of these dietary interventions. Altered crystallin (αA and αB) distribution profile, their expression, activity of carbohydrate metabolizing enzymes, and antioxidant status were significantly annulled by these dietary treatments. Physical and visual observation of the photomicrographs of the lenses of treated rats indicated that these dietary interventions delayed cataractogenesis in diabetic rats.</p> <p><i>Conclusions</i>: Overall, the present investigation evidenced a beneficial modulation of the progression of cataractogenesis by dietary fenugreek seeds and onion, implicating their potential in ameliorating cataract in diabetics.</p

Determination of bioaccessibility of β-carotene in vegetables by in vitro methods

Abstract The in vitro method in use for the determination of β-carotene bioaccessibility involves simulated gastrointestinal digestion followed by ultracentrifugation to separate the micellar fraction containing bioaccessible β-carotene and its quantitation. In this study, the suitability of two alternatives viz., membrane filtration and equilibrium dialysis were examined to separate the micellar fraction. Values of β-carotene bioaccessibility obtained with the membrane filtration method were similar to those obtained by the ultracentrifugation method. Equilibrium dialysis was found not suitable for this purpose. Among the vegetables analyzed, fenugreek leaves had the highest content of β-carotene (9.15 mg/100 g), followed by amaranth (8.17 mg/100 g), carrot (8.14 mg/100 g) and pumpkin (1.90 mg/100 g). Percent bioaccessibility of β-carotene ranged from 6.7 in fenugreek leaves to 20.3 in carrot. Heat treatment of these vegetables by pressure cooking and stir-frying had a beneficial influence on the bioaccessibility of β-carotene from these vegetables. The increase in the percent bioaccessibility of β-carotene as a result of pressure-cooking was 100, 48 and 19% for fenugreek leaves, amaranth and carrot, respectively. Stir-frying in presence of a small quantity of oil led to an enormous increase in the bioaccessibility of β-carotene from these vegetables, the increase being 263% (fenugreek leaves), 192% (amaranth leaves), 63% (carrot) and 53% (pumpkin)