Impact of Cassava Starch Varieties on the Physiochemical Change during Enzymatic Hydrolysis.

The enzymatic modification of starch extends its industrial use to flavor delivery and probiotic encapsulants, among other uses. However, it is not known how starch from different cassava varieties responds to enzymatic hydrolysis. Starches from two Ecuadorian cassava varieties (INIAP 650, an edible starch, and INIAP 651, an industrial starch) were partially modified at three enzymatic hydrolysis degrees (0%, 30%, and 50%), and their physicochemical properties were assessed. The structural analysis revealed that both varieties showed progressive structural damage as hydrolysis increases, probably due to exo-hydrolysis. However, deeper pores were observed in INIAP 651 with the SEM analysis. The crystallinity percentage obtained by XRD analyses remained constant in INIAP 651 and decreased (by 26%) in INIAP 650 (p < 0.05). In addition, the amylose−lipid complex index in INIAP 650 remained constant, while INIAP 651 increased (p < 0.05) at 30% hydrolysis (by 93%). In both varieties, hydrolysis increased (p < 0.05) the water holding capacity (WHC) (by 10−14%) and the water binding capacity (WBC) (by 16%), but 50% hydrolysis of INIAP 650 was needed to significantly affect these properties. No differences were observed in the varieties' thermal properties. Regarding the rheological properties, the variety did not influence the changes in the storage module (G') and the loss modulus (G″) with the hydrolysis (p > 0.05). However, the phase angle decreased significantly (p < 0.05) with the hydrolysis, being higher in the INIAP 650 variety than in the INIAP 651 variety. In general, the results indicate that the variety affects the response of the starch granule to enzymatic hydrolysis (noticeable in the principal component analysis, PCA) and opens up the possibility to modulate starch properties.

Trichoderma sp. spores and Kluyveromyces marxianus cells magnetic separation: Immobilization on chitosan-coated magnetic nanoparticles.

In the present study, the interactions between chitosan-coated magnetic nanoparticles (C-MNP) and Trichoderma sp. spores as well as Kluyveromyces marxianus cells were studied. By Plackett-Burman design, it was demonstrated that factors which directly influenced on yeast cell immobilization and magnetic separation were inoculum and C-MNP quantity, stirring speed, interaction time, and volume of medium, while in the case of fungal spores, the temperature also was disclosed as an influencing factor. Langmuir and Freundlich models were applied for the mathematical analysis of adsorption isotherms at 30°C. For Trichoderma sp. spore adsorption isotherm, the highest correlation coefficient was observed for lineal function of Langmuir model with a maximum adsorption capacity at 5.00E + 09 spores (C-MNP g-1). Adsorption isotherm of K. marxianus cells was better adjusted to Freundlich model with a constant (Kf) estimated as 2.05E + 08 cells (C-MNP g-1). Both systems may have a novel application in fermentation processes assisted with magnetic separation of biomass.

The Effect of Stabilized Rice Bran Addition on Physicochemical, Sensory, and Techno-Functional Properties of Bread.

Rice bran (RB) is a valuable byproduct derived from rice milling that represents an excellent opportunity for dietary inclusion. Bioactive components with antioxidant potential have been reported in RB, gaining the considerable attention of researchers. However, RB requires a stabilization process after milling to prevent it from becoming rancid and promote its commercial consumption. The aim of this study was to evaluate the effects of substituting stabilized rice bran (SRB) for wheat flour at levels of 10, 15, 20 and 25% on the proximate composition, dietary fiber, dough rheology, antioxidant properties, content of bioactive compounds, and sensory attributes of white wheat-based bread. Results indicated that the incorporation of SRB increased the bread's insoluble dietary fiber, phytic acid, total polyphenol content, γ-oryzanol, γ-aminobutyric acid, and antioxidant properties, while decreased its water absorption capacity, elasticity, volume, ß-glucans, and soluble dietary fiber content. Moreover, substituting wheat flour for SRB at levels higher than 15% affected sensory attributes, such as color, odor, flavor, and softness. This study highlights the potential application of SRB flour in bread-making to increase nutritional, and functional properties of white wheat bread.