Impact of flour particle size and autoclaving on β-glucan physicochemical properties and starch digestibility of barley rusks as assessed by in vitro assays

In vitro and in vivo glycemic responses and antioxidant potency of acorn and chickpea fortified gluten-free breads

Gluten-free (GF) breads, based on rice flour and corn starch (50:50), were fortified with a mixture of acorn flour (ACF) - chickpea flour (CPF) at 30% substitution level of corn starch (i.e., rice flour:corn starch:ACF-CPF 50:20:30) using different flour blends of ACF:CPF at weight ratios of 5:25, 7.5:22.5, 12.5:17.5, and 20:10 in order to improve the nutritional quality and antioxidant potential as well as the glycemic responses of the GF breads; a control GF bread with rice flour:corn starch 50:50 ratio was also prepared. ACF was richer in total phenolic content than CPF, whereas CPF was characterized by higher amounts of total tocopherols and lutein compared to ACF. For both ACF and CPF as well as the fortified breads, the most abundant phenolic compounds were gallic (GA) and ellagic (ELLA) acids as found by HPLC-DAD analysis, while a hydrolysable tannin, valoneic acid dilactone, was also identified and quantified by HPLC-DAD-ESI-MS in high amount in the ACF-GF bread having the highest level of ACF (ACF:CPF 20:10), even though it seemed to decompose during breadmaking, possibly into GA and ELLA. Therefore, the inclusion of these two raw materials as ingredients in GF bread formulations resulted in baked products with enhanced concentrations of such bioactive compounds and higher antioxidant activities, as indicated by three different assays (DPPH, ABTS and FRAP). The extent of glucose release, as evaluated by an in vitro enzymic assay, was negatively correlated (r = -0.96; p = 0.005) with the level of added ACF, and was significantly reduced for all ACF-CPF fortified products when compared with their non-fortified GF counterpart. Furthermore, the GF bread containing a flour mixture of ACP:CPF at a weight ratio of 7.5:22.5, was subjected to an in vivo intervention protocol to assess the glycemic response when consumed by 12 healthy volunteers; in this case, white wheat bread was used as reference food. The glycemic index (GI) of the fortified bread was significantly lower compared to the control GF bread (97.4 versus 159.2, respectively), which along with its lower amount of available carbohydrates and the higher level of dietary fibers, resulted in a significantly reduced glycemic load (7.8 versus 18.8 g per serving of 30 g). The present findings underlined the effectiveness of acorn and chickpea flours in improving the nutritional quality and glycemic responses of fortified GF breads with these flours.

Lipase Inactivation Kinetics of Tef Flour with Microwave Radiation and Impact on the Rheological Properties of the Gels Made from Treated Flour

In recent years, many efforts are being made to produce tef-based food for its nutritive and health-promoting advantages. Tef grain is always whole milled because of its tiny grain size and whole flours contain bran (pericarp, aleurone, and germ) where major non-starch lipids could be deposited along with the lipid-degrading enzymes: lipase and lipoxygenase. As lipoxygenase shows little activity in low moisture, the inactivation of lipase is the common objective for most heat treatments to extend the shelf life of flours. In this study, tef flour lipase inactivation kinetics via hydrothermal treatments assisted using microwaves (MW) were studied. The effects of tef flour moisture level (12%, 15%, 20%, and 25%) and MW treatment time (1, 2, 4, 6, and 8 min) on flour lipase activity (LA) and free fatty acid (FFA) content were evaluated. The effects of MW treatment on flour pasting characteristics and the rheological properties of gels prepared from the treated flours were also explored. The inactivation process followed a first-order kinetic response and the apparent rate constant of thermal inactivation increased exponentially with the moisture content of the flour (M) according to the equation 0.048·exp (0.073·M) (R² = 0.97). The LA of the flours decreased up to 90% under the studied conditions. MW treatment also significantly reduced (up to 20%) the FFA level in the flours. The rheological study confirmed the presence of significant modifications induced by the treatment, as a lateral effect of the flour stabilization process.

Dry heating, moist heating, and microwave irradiation of cold-climate-adapted barley grain-Effects on ruminant-relevant carbohydrate and molecular structural spectral profiles

Different feed processing techniques affect barley digestibility and nutrient utilization in ruminants. To our knowledge, there are few studies on the interactive relationship between carbohydrate molecular structure profiles of cool-season-adapted barley grain and nutritional characteristics for ruminants. The objectives of this study were: (1) to investigate the effect of different technological processing methods on carbohydrate chemical profiles, Cornell Net Carbohydrate and Protein System-carbohydrate subfractions, ruminal and intestinal carbohydrate digestion of barley grain in dairy cows; (2) to study the effect of heat processing on carbohydrate molecular structure of barley grain using advanced molecular spectroscopy; and (3) to associate processing-induced changes in carbohydrate molecular structure with changes in carbohydrate metabolic profiles in dairy cows. Barley grain samples collected from Crop Research Field in Western Canada underwent four different processing treatments: control, dry heating (120°C for 60 min in an air-ventilated oven), moist heating (120°C for 60 min in an autoclave), and microwave irradiation (900 W and 2450 MHz for 5 min in a microwave). The heating conditions used in the current study induced some changes in rumen-degradable and -undegradable digestible fibre (CB3) fraction. Intestinally digestible CB3 was decreased after moist heating. Moist heating decreased starch digestibility compared to the other three treatments. The processing-induced carbohydrate molecular structure changes, which was revealed by advanced vibrational molecular spectroscopic technique (attenuated total reflectance-Fourier transform infrared), could be used to predict carbohydrate nutritional value.

Effect of rice flour ultrafine particle size on β-glucanase inactivation by microwave treatments and pasting properties in treated flours

The main problem in developing gluten-free products enriched with β-glucans (BG) is the hydrolysis they suffer due to the endogenous β-glucanase content of raw materials. The depolymerization causes a decrease in the molecular weight and viscosity, which is the most important parameter related to the health claims of BG. Hence, it is necessary to inactivate the β-glucanase. Therefore, this study aimed to inactivate the β-glucanase activity present in rice flour (Indica variety) with fine particle size using the microwave (MW) hydrothermal treatment method. The rice flour was conditioned at three different humidities 13, 16, 19 and 25%. Samples of 50 g were subjected to different microwave treatments 1, 2, 4 and 8 min, at 900 W power at 20 seconds intervals of treatment and 1-minute rest. The effect of particle size on inactivating the β-glucanase activity and the effect of MW treatment on the flour pasting property were also studied. The inactivation process followed a first-order kinetic response, and the apparent rate constant of thermal inactivation increased exponentially with the moisture content (M) of the flour, according to the equation -0.02t·exp (0.19·M) (R2 = 0.987). Among the treatments employed 4 min treatment at 25% initial M was found effective for complete β-glucanase inactivation. The effect of flour particle size did not show a significant (p> 0.05) difference on the efficiency of β-glucanase inactivation. Keywords: particle size, β-glucans, rice flour, microwave treatment, β-glucanase activity.

Impact of Roasted Yellow Split Pea Flour on Dough Rheology and Quality of Fortified Wheat Breads

Roasted yellow split pea (YSP) flours were used to substitute wheat flour, at 10–20% (flour basis) in wheat bread formulations. Rheometry showed that roasted YSP flour addition increased elasticity and resistance to deformation and flow of the composite doughs, particularly at 20% substitution; instead, at 10% addition (either raw or roasted YSP flour), there were no effects on dough rheology and bread textural properties. Breads fortified with roasted YSP flour at levels >10% exhibited lower loaf-specific volume and harder crumb compared to control (bread without YSP flour). Moreover, only breads with 20% roasted YSP flour displayed a significantly higher staling extent and rate, compared to control, as assessed by large deformation mechanical testing and calorimetry (starch retrogradation) of crumb preparations. This formulation also showed a large increase in β-sheets and β-turns at the expense of α-helix and random coil conformations in protein secondary structure as assessed by FTIR spectroscopy. Roasting of YSP effectively masked the “beany” and “grass-like” off-flavors of raw YSP flour at 10% substitution. Overall, roasted YSP flour at the 10% level was successfully incorporated into wheat bread formulations without adversely affecting dough rheology, bread texture, and shelf-life, resulting in final products with a pleasant flavor profile.

Reinvigorating Modern Breadmaking Based on Ancient Practices and Plant Ingredients, with Implementation of a Physicochemical Approach

In this study, the potential use of ancient plant ingredients in emerging bakery products based on possible prehistoric and/or ancient practices of grinding and breadmaking was explored. Various ancient grains, nuts and seeds (einkorn wheat, barley, acorn, lentil, poppy seeds, linseed) were ground using prehistoric grinding tool replicas. Barley-based sourdough prepared by multiple back-slopping steps was added to dough made from einkorn alone or mixed with the above ingredients (20% level) or commercial flours alone (common wheat, spelt, barley). Sieving analysis showed that 40% of the einkorn flour particles were >400 μm, whereas commercial barley and common wheat flours were finer. Differential scanning calorimetry revealed that lentil flour exhibited higher melting peak temperature and lower apparent enthalpy of starch gelatinization. Among all bread formulations tested, barley dough exhibited the highest elastic modulus and complex viscosity, as determined by dynamic rheometry; einkorn breads fortified with linseed and barley had the softest and hardest crust, respectively, as indicated by texture analysis; and common wheat gave the highest loaf-specific volume. Barley sourdough inclusion into einkorn dough did not affect the extent of starch retrogradation in the baked product. Generally, incorporation of ancient plant ingredients into contemporary bread formulations seems to be feasible.

A Concise Review on the Molecular Structure and Function Relationship of β-Glucan

β-glucan is a non-starch soluble polysaccharide widely present in yeast, mushrooms, bacteria, algae, barley, and oat. β-Glucan is regarded as a functional food ingredient due to its various health benefits. The high molecular weight (Mw) and high viscosity of β-glucan are responsible for its hypocholesterolemic and hypoglycemic properties. Thus, β-glucan is also used in the food industry for the production of functional food products. The inherent gel-forming property and high viscosity of β-glucan lead to the production of low-fat foods with improved textural properties. Various studies have reported the relationship between the molecular structure of β-glucan and its functionality. The structural characteristics of β-glucan, including specific glycosidic linkages, monosaccharide compositions, Mw, and chain conformation, were reported to affect its physiochemical and biological properties. Researchers have also reported some chemical, physical, and enzymatic treatments can successfully alter the molecular structure and functionalities of β-glucan. This review article attempts to review the available literature on the relationship of the molecular structure of β-glucan with its functionalities, and future perspectives in this area.

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.