Effects of germination and high hydrostatic pressure processing on mineral elements, amino acids and antioxidants in vitro bioaccessibility, as well as starch digestibility in brown rice (Oryza sativa L.)

Impact of high hydrostatic pressure on non-volatile and volatile compounds of squid muscles.

The influences of high hydrostatic pressure (HHP), microwave heating (MW), and boiling (BL) on the chemical compositions, phytic acid, tannin, saponin, trypsin inhibitor activity, protein digestibility, and microstructure of buckwheat grains were investigated. All three processes decreased the starch, protein, fat, and ash contents. HHP and MW reduced the total flavonoids by 19 %, lower than that in the BL samples (38 %). HHP lowered the ω-6/ω-3 ratio by 6.4 %, while MW and BL increased the ω-6/ω-3 ratio by 4.9 and 2.6 %, respectively. MW reduced essential amino acids and total amino by 3.1 and 4.8 %, respectively, but the reductions were lower than in other treated samples. Phytic acid was lowered by 45.5 % in HHP samples, by 33.4 % in MW samples, and by 62.7 % in BL samples. Trypsin inhibitor activity decreased by 63 % in BL samples and by 13 % in other treated samples. BL induced the highest losses of tannin (35.7 %) and saponin (27.6 %), followed by MW treatment (27.5 and 20.1 %) and HHP treatment (19.9 and 14.6 %). The protein digestibility increased by 0.8, 3.6, and 6.5 % under HHP, MW, and BL conditions, respectively. Taken together, three treatments offered varying degrees of decreases in the antinutritional factors and increases in in vitro protein digestibility, as well as retention of nutritional components of the buckwheat. Therefore, it might be suggested that special care should be taken when selecting a processing method for the development of health-promoting buckwheat products.

Influences of High Hydrostatic Pressure, Microwave Heating, and Boiling on Chemical Compositions, Antinutritional Factors, Fatty Acids, In Vitro Protein Digestibility, and Microstructure of Buckwheat

Over the last several decades, γ-aminobutyric acid (GABA) has attracted much attention due to its diverse physiological implications in plants, animals, and microorganisms. GABA naturally occurs in plant materials and its concentrations may vary considerably, from traces up to μmol/g (dry basis) depending on plant matrix, germination stage, and processing conditions, among other factors. However, due to its important biological activities, considerable interest has been shown by both food and pharmaceutical industries to improve its concentration in plants. Natural and conventional treatments such as mechanical and cold stimulation, anoxia, germination, enzyme treatment, adding exogenous glutamic acid (Glu) or gibberellins, and bacterial fermentation have been shown effective to increase the GABA concentration in several plant materials. However, some of these treatments can modify the nutritional, organoleptic, and/or functional properties of plants. Recent consumer demand for food products which are "healthy," safe and, having added benefits (nutraceuticals/functional components) has led to explore new ways to improve the content of bioactive compounds while maintaining desirable organoleptic and physicochemical properties. Along this line, nonthermal processing technologies (such as high-pressure processing, pulsed electric fields, and ultrasound, among others) have been shown as means to induce the biosynthesis and accumulation of GABA in plant foods; and the main findings so far reported are presented in this review. Moreover, the most novel tools for the identification of metabolic response in plant materials based on GABA analysis will be also described.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/1541-4337.12285

Influence of Innovative Processing on γ-Aminobutyric Acid (GABA) Contents in Plant Food Materials.

Comparison of biochemical composition and non-volatile taste active compounds in raw, high hydrostatic pressure-treated and steamed oysters Crassostrea hongkongensis

High hydrostatic pressure (HP) with approximately below 400 MPa can induce a transformation of food materials to an alternative form, where membrane systems are damaged but certain enzymes are still active. HP treatment of water soaked brown rice grain could modify the mass transfer inside and apparent activities of enzymes, resulting in HP-dependent change of distribution of free amino acids. Thus, the distribution of free amino acids in brown rice grain during preservation after HP treatment was analyzed. Just after HP treatment at 200 MPa for 10 min, the distribution of free amino acids was not apparently different from that of untreated control. In contrast, after 1 to 4 days preservation at 25°C, amino acids, such as Ala, Glu, Gly, Asp and Val, showed higher concentrations than those in control. This result suggested that HP treatment induced proteolysis to produce free amino acids. However, Gln, Thr and Cys, showed no apparent difference, suggesting that conversion of certain amino acids produced by proteolysis occurred. Moreover, the concentration of γ-aminobutyric acid (GABA) in HP-treated sample was higher than that in untreated control. These results suggested that HP treatment induced alteration of distribution of free amino acids of rice grains via proteolysis and certain amino acids metabolism pathways.

https://iopscience.iop.org/article/10.1088/1742-6596/215/1/012171/pdf

Y Narahara

Papers

Effects of high hydrostatic pressure on distribution dynamics of free amino acids in water soaked brown rice grain