Effects of non-starch polysaccharides on physicochemical properties and in vitro starch digestibility of rice starches

Regulation of baking quality and starch digestibility in whole wheat bread based on β-glucans and protein addition strategy: Significance of protein-starch-water interaction in dough

Whole wheat bread has high nutritional value but is characterized by inferior quality and a high glycemic index. Studies have shown that adding β-glucans and protein can improve bread quality. This study investigated the effects of added oat β-glucan, barley β-glucan, or yeast β-glucan on protein synergy and whole wheat dough and bread quality. The mixing properties, rheological properties, and scanning electron microscopy observations showed that the addition of β-glucan promoted the formation of gluten networks, while the synergy between the wheat proteins and β-glucan resulted in a more robust and stable gluten network and a stronger physical starch envelope. Rapid visco-analysis and thermal property evaluations showed that β-glucan addition inhibited the thermal degradation, gelatinization, and retrogradation of starch. Based on the bread quality results, it was found the β-glucan could cause some damage to the bread baking quality. For example, the hardness of samples with oats, barley, and yeast increased to 881.69 g, 952.97 g, and 631.75 g, respectively, compared to samples without β-glucan (317.49 g), whereas the inclusion of yeast β-glucan proved to be less detrimental. Protein and β-glucan both reduced starch digestion to some degree, and showed better synergistic effects, with the lowest estimated glycemic index of 70.08 observed in bread containing added yeast β-glucan and protein. Therefore, yeast β-glucan and protein mixtures could be selected as viable formulations for enhancing the quality of whole wheat bread.

Reducing the glycemic impact of carbohydrates on foods and meals: Strategies for the food industry and consumers with special focus on Asia

Type 2 diabetes is increasingly prevalent in Asia, which can be attributed to a carbohydrate-rich diet, consisting of foods in the form of grains, for example, rice, or a food product made from flours or isolated starch, for example, noodles. Carbohydrates become a health issue when they are digested and absorbed rapidly (high glycemic index), and more so when they are consumed in large quantities (high glycemic load). The principal strategies of glycemic control should thus aim to reduce the amount of carbohydrate available for digestion, reduce the rate of digestion of the food, reduce the rate of glucose absorption, and increase the rate of glucose removal from blood. From a food perspective, the composition and structure of the food can be modified to reduce the amount of carbohydrates or alter starch digestibility and glucose absorption rates via using different food ingredients and processing methods. From a human perspective, eating behavior and food choices surrounding a meal can also affect glycemic response. This review therefore identifies actionable strategies and opportunities across foods and meals that can be considered by food manufacturers or consumers. They are (a) using alternative ingredients, (b) adding functional ingredients, and (c) changing processing methods and parameters for foods, and optimizing (a) eating behavior, (b) preloading or co-ingestion of other macronutrients, and (c) meal sequence and history. The effectiveness of a strategy would depend on consumer acceptance, compatibility of the strategy with an existing food product, and whether it is economically or technologically feasible. A combination of two or more strategies is recommended for greater effectiveness and flexibility.

Effects of Transglutaminase on the Protein Network and In Vitro Starch Digestibility of Asian Wheat Noodles

Wheat noodles are a staple commonly consumed in Asia, but high intakes have been associated with type 2 diabetes due to its rapid starch digestibility. We hypothesised that protein network-binding via transglutaminase (TG) would form a stronger barrier encapsulating the starch granules to limit enzymatic access and digestion. The amount of glucose release decreased significantly with increasing TG concentration, with a reduction of approximately 16% with 2% TG after 120 min of digestion. The slower rate of glucose release during the first 60 min of digestion for 2% compared to 0% TG suggested impeded first stage enzymatic access rather than second stage starch hydrolysis into glucose. Upon increasing the TG concentration, confocal microscopy revealed a denser protein network with increased connectivity, supported by a decrease in protein solubility and gelatinisation enthalpy, and increased firmness and work of shear. Therefore, transglutaminase can potentially be used to reduce starch digestibility in wheat noodles via protein network-binding.