The Potential of an in Vitro Digestion Method for Predicting Glycemic Response of Foods and Meals

The role of food structure in gastric-emptying rate, absorption and metabolism

The high levels of non-communicable diseases such as CVD and type 2 diabetes mellitus are linked to obesity and poor diet. This continuing emphasis on health in relation to food is proving a powerful driver for the development of cheap but palatable and more functional foods. However, the efficacy of such foods is often hard to prove in human subjects. Thus, a suite of tools has been developed including in silico and in vitro simulations and animal models. Although animal models offer physiologically relevant platforms for research, their use for experimentation is problematic for consumers. Thus, in vitro methods such as Infogest protocols have been developed to provide digestion endpoints or even an indication of the kinetics of digestion. These protocols have been validated for a range of food systems but they still miss the final absorption step. This review discusses the use of such in vitro models and what further steps need to be included to make the bioaccessibility determination more relevant to bioavailability and human health.

The Glycemic Index and Human Health with an Emphasis on Potatoes

Diabetes and obesity are associated with the excessive intake of high-glycemic index (GI) carbohydrates, increased glycemic load (GL) foods, and inactive lifestyles. Carbohydrate-rich diets affect blood glucose levels. GI is an indicator of the impact of a specific food on blood glucose, while GL represents the quantity and quality of carbohydrates in the overall diet and their interactions. There are in vitro and in vivo methods for estimating GI and GL. These values are useful human health markers for conditions such as diabetes, obesity, and pregnancy. Potato is a major starchy vegetable, which is consumed widely and is the fourth most important crop globally. However, the GI of diets rich in starchy vegetables such as potatoes has not been studied in detail. The GI values in potatoes are affected by external and internal factors, such as methods of cooking, methods of processing, resistant starches, cultivation methods, mixed meals and food additions, and hormone levels. This review summarizes how these factors affect the GI and GL associated with diets containing potatoes. Understanding the impacts of these factors will contribute to the development of new and improved potato varieties with low GI values. The consumption of low-GI foods will help to combat obesity. The development of low-GI potatoes may contribute to the development of meal plans for individuals living with diabetes and obesity.

Fortification of Durum Wheat Fresh Pasta with Maqui (Aristotelia chilensis) and Its Effects on Technological, Nutritional, Sensory Properties, and Predicted Glycemic Index

Pasta, a staple food worldwide consumed, was fortified with maqui (Aristotelia chilensis) berry powder (MBP) and the effect of MBP inclusion was evaluated concerning technological, nutritional, and sensory properties. Fresh pasta samples were formulated by replacing 0, 7.5, and 15 g 100 g−1 of durum wheat semolina with MBP. The inclusion of MBP did not affect the moisture content, but the water activity decreased in the fortified samples, while pH values decreased with increasing MBP levels in the recipe. The pasta fully cooking time and the swelling index were reduced, while the cooking loss and the firmness increased with increasing MBP levels. In addition, MBP increased the total dietary fiber, ash, and phenol contents, along with the in vitro antioxidant activities. The starch hydrolysis index and the predicted glycemic index of cooked fresh pasta decreased along with the increase of MBP addition. The MPB addition to fresh pasta could represent a valuable strategy for increasing its nutritional value, maintaining pasta’s technological properties without affecting the sensory acceptability.

Structural breakdown of starch-based foods during gastric digestion and its link to glycemic response: In vivo and in vitro considerations

The digestion of starch-based foods in the small intestine as well as factors affecting their digestibility have been previously investigated and reviewed in detail. Starch digestibility has been studied both in vivo and in vitro, with increasing interest in the use of in vitro models. Although previous in vivo studies have indicated the effect of mastication and gastric digestion on the digestibility of solid starch-based foods, the physical breakdown of starch-based foods prior to small intestinal digestion is often less considered. Moreover, gastric digestion has received little attention in the attempt to understand the digestion of solid starch-based foods in the digestive tract. In this review, the physical breakdown of starch-based foods in the mouth and stomach, the quantification of these breakdown processes, and their links to physiological outcomes, such as gastric emptying and glycemic response, are discussed. In addition, the physical breakdown aspects related to gastric digestion that need to be considered when developing in vitro-in vivo correlation in starch digestion studies are discussed. The discussion demonstrates that physical breakdown prior to small intestinal digestion, especially during gastric digestion, should not be neglected in understanding the digestion of solid starch-based foods.

Glycemic Index of Gluten-Free Bread and Their Main Ingredients: A Systematic Review and Meta-Analysis

This study aimed to perform a systematic review and meta-analysis of the glycemic index (GI) of gluten-free bread (GFB) and its main ingredients. The systematic review followed PRISMA guidelines, using seven electronic databases (PubMed, EMBASE, Scopus, Science Direct, Web of Science, gray literature research with Google Scholar, and patents with Google Patent tool), from inception to November 2020. Eighteen studies met the inclusion criteria evaluating 132 GFB samples. Five articles tested GI in vivo, eleven in vitro; and two studies tested both methods. The analysis showed that 60.7% (95% CI: 40.2-78.1%) of the samples presented high glycemic indexes, evidencing a high glycemic profile for GFB. Only 18.2% (95% CI: 11.7-27.2%) of the bread samples presented in the studies were classified as a low GI. Meta-analysis presented moderate/low heterogenicity between studies (I2 = 61% and <1% for both high and low GIs) and reinforced the proportion of high GIs. Lower GIs were found in formulations based on Colocasia esculenta flour or enriched with fiber, yogurt and curd cheese, sourdough, psyllium, hydrocolloids, enzymes, fructans, and resistant starch, highlighting the efficacy of these ingredients to lower GFBs' GI. GFB tends to present high GI, impacting the development of chronic diseases when consumed.

Predicting Glycemic Index and Glycemic Load from Macronutrients to Accelerate Development of Foods and Beverages with Lower Glucose Responses

Low glycemic index (GI) and/or low glycemic load (GL) are associated with decreased risks of type-2 diabetes and cardiovascular disease. It is therefore relevant to consider GI and GL in the early phases of the development of packaged foods and beverages. This paper proposes a model that predicts GI and GL from macronutrient composition, by quantifying both the impact of glycemic carbohydrates and the GI-lowering effects of nutrients such as proteins, fats and fibers. The precision of the model is illustrated using data on 42 breakfast cereals. The predictions of GI (r = 0.90, median residual = 2.0) and GL (r = 0.96, median residual = 0.40 g) compete well with the precision of the underlying in-vivo data (Standard Error SE = 3.5 for GI). This model can guide product development towards lowering GI and GL, before final confirmation by in vivo testing.

Influence of Yeast β-Glucan on Cookies Sensory Characteristics and Bioactivities

β-Glucan is biologically active polysaccharide, ubiquitously found in many grains, bacteria, and fungi and much yeast. The aim of this study was to determine the effect of substituting wheat flour by 1, 2, and 4% yeast isolated β-glucan in cookies on the sensory acceptance, antioxidants, oxidative stability, and quality evaluation which were investigated. According to the results, cookies supplemented at 2% yeast β-glucan were proved satisfactory on sensory quality perspective. During the storage study it was found that cookies made with 2 and 4% β-glucan have effectively (p>0.05) kept the peroxide value (PV) within acceptable range, demonstrating the promising role of β-glucan in deterring oxidative. It is further noted that 2 or 4% β-glucan incorporated cookies assimilated highest absorption spectra, suggesting the retardation in freshness losses, with having minimum microbial loads, showing microbiological safety. β-Glucan fortification in foods is technologically and economically feasible, suggesting that a significant prospect of β-glucan as low-cost food ingredient in formulating cookies at 2% offers exciting new use of β-glucan of yeast origin.

Nutraceutical, Anti-Inflammatory, and Immune Modulatory Effects of β-Glucan Isolated from Yeast

β-Glucan is a dietary fibre, found in many natural sources, and controls chronic metabolic diseases effectively. However, β-glucan from the yeast has rarely been investigated. Objectively, conditions were optimized to isolate β-glucan from the yeast (max. 66% yield); those optimized conditions included 1.0 M NaOH, pH 7.0, and 90°C. The purity and identity of the isolated β-glucan were characterized through FT-IR, SEM, DSC, and physicofunctional properties. The obtained results from DSC revealed highly stable β-glucan (m.p., 125°C) with antioxidant activity (TAC value 0.240 ± 0.0021 µg/mg, H₂O₂ scavenging 38%), which has promising bile acid binding 40.463% and glucose control (in vitro). In line with these results, we evaluated the in vivo anti-inflammatory potential, that is, myeloperoxidase activity and reduction in MDA and NO; protective effect on proteins and keeping viscosity within normal range exhibited improvement. Also, the in vivo cholesterol binding and reduction in the skin thickness by β-glucan were highly encouraging. Finally, our results confirmed that yeast β-glucan is effective against some of the inflammatory and oxidative stress markers studied in this investigation. In general, the effect of 4%  β-glucan was more noticeable versus 2%  β-glucan. Therefore, our results support the utilization of β-glucan as a novel, economically cheap, and functional food ingredient.