[ effect of whey protein on glycemic index and satiety index of potatoes]

Introduction: Effects of whey protein on reduction of blood glucose and appetite have been reported. In the present study the effects of whey protein on glycemic index [GI] and satiety index [SI] of mashed potato were investigated

Materials and Methods: To determine the GI, 10 healthy subjects [6 male, 4 female] were enrolled in the study on 4 separate days at 1 week intervals. On each day, they were given potato puree, potato+4.5 or 9 grams of whey protein or glucose solution in random order. Fasting blood samples were taken at fasting and at 15, 30, 45, 60, 90 and 120 minutes after food ingestion and the GI was calculated. To determine the SI, 20 healthy subjects [10 male, 10 female] were enrolled and on 4 separate days at one week intervals, daily they were given white bread, potato puree, potato+4.5 or 9 grams of whey protein in random order. The satiety was measured at fasting and every 15 min over the next 2 hours after food ingestion; using a satiety questionnaire and the SI was calculated

Results: Adding whey protein to mashed potato reduced the area under the blood glucose curve, though it was not significant [p=0.155]. No did the GI of potato change significantly [p=0.245]. However, the area under the satiety curve of potato increased significantly by adding whey protein [p<0.001]; SI of potato was also increased significantly by adding both doses of whey protein [p<0.001]

Conclusion: Although adding whey protein did not change the GI of potato, but it significantly increased its SI

[Roasted chickpea flour decreases glycemic index and glycemic load of white bread]

Introduction: Postprandial blood glucose concentration is one of the factors related to chronic diseases. This study examines the postprandial glucose response to bread made of roasted chickpea flour and white wheat flour. The effect of the roasted chickpea flour on glycemic index, glycemic load, and glycemic profile of white bread was also investigated

Materials and Methods: In this cross-over randomized study, 10 healthy subjects [8 females, 2 males] enrolled in the study on 4 separate days with one week intervals. On each day, the blood glucose at fasting and at 15, 30, 45, 60, 90 and 120 minutes after ingestion of glucose solution, white bread and bread containing 1/4 and 1/2 roasted chickpea flour was measured. The glycemic index, glycemic load and glycemic profile were calculated

Results: Postprandial blood glucose response to chickpea breads was significantly lower than to white bread [p<0.001]. The incremental area under the glucose curve after ingestion of chickpea breads was significantly lower than for white bread [P<0.001]. The glycemic index and glycemic load of chickpea breads were also significantly lower than white bread [P<0.001]. No significant differences were observed between the glycemic profiles of the test breads. However, the peak value of blood glucose was significantly lower after ingestion of 1/4 chickpea bread [P=0.017] and 1/2 chickpea bread, compared to white bread [P<0.001]

Conclusion: Adding roasted chickpea flour not only improves postprandial blood glucose response, but also considerably reduces the glycemic index and glycemic load of white bread

[Effect of different cooking methods on the content of vitamin C in some vegetables]

Vitamin C is considered as the indicator of process severity, because of its high sensitivity to heat. There is an inverse relationship between vitamin C retention and the process severity. The aim of this study was to determine the effect of different common cooking methods on process severity and decrease amount of vitamin C in some vegetables. In this study, potatoes were tested as boiled [with peel, without peel, sliced], shallow and deep fried, and cooking under pressure [with peel, without peel, sliced].Onions were tested as boiled [whole and sliced] and microwave [whole and sliced]. Leafy vegetables: Leek, leaf of beet, parsley, coriander, common dill and the mixed of them were tested as boiled fried. All tests performed as triplicate and the contents of vitamin C retention were determined by colorimetric method according to the instruction number 5609 of the Institute of Standards and Industrial Research of Iran and were compared to the contents of vitamin C in raw vegetables. The highest decrease of vitamin C was observed in boiled, sliced [without peel] and shallow fried potatoes and onions. In leafy vegetables highest loss of vitamin C was observed from boiled fried. The loss of vitamin C in potatoes and onions by using microwave were small and their vitamin C contents were similar to raw vegetables. The maximum retention of vitamin C in potatoes and onions are obtained by microwave method, with peel and whole, respectively