Looking for peptides from rice starch processing by-product: Bioreactor production, anti-tyrosinase and anti-inflammatory activity, and in silico putative taste assessment.

One of the major challenges for the modern society, is the development of a sustainable economy also aiming at the valorization of agro-industrial by-products in conjunction with at a significant reduction of generated residues from farm to retail. In this context, the present study demonstrates a biotechnological approach to yield bioactive peptides from a protein fraction obtained as a by-product of the rice starch production. Enzymatic hydrolysis, with the commercial proteases Alcalase and Protamex, were optimized in bioreactor up to 2 L of volume. The two best digestates, selected with respect to peptide release and extract antioxidant capacity, were further fractionated (cut-offs of 10, 5, and 1 kDa) via cross-flow filtration. Amino acid composition indicated that most of the fractions showed positive nutritional characteristics, but a putative bitter taste. A fraction obtained with Alcalase enzyme (retentate 8 kDa) exerted anti-inflammatory potential, while the smaller molecular weight fractions (retentate 1-5 kDa and permeate < 1 kDa) were more active in tyrosinase inhibition. The latter were further sub-fractionated by size-exclusion chromatography. From the 15 most anti-tyrosinase sub-fractions, 365 peptide sequences were identified via liquid chromatography coupled with high resolution mass spectrometry. The present data support the possible exploitation of bioactive peptide from rice starch by-product as ingredients into food, nutraceutical, pharmaceutical, and cosmetic formulations.

Microbial Fermentation of Industrial Rice-Starch Byproduct as Valuable Source of Peptide Fractions with Health-Related Activity.

The rice-starch processing industry produces large amounts of a protein-rich byproducts during the conversion of broken rice to powder and crystal starch. Given the poor protein solubility, this material is currently discarded or used as animal feed. To fully exploit rice's nutritional properties and reduce this waste, a biotechnological approach was adopted, inducing fermentation with selected microorganisms capable of converting the substrate into peptide fractions with health-related bioactivity. Lactic acid bacteria were preferred to other microorganisms for their safety, efficient proteolytic system, and adaptability to different environments. Peptide fractions with different molecular weight ranges were recovered from the fermented substrate by means of cross-flow membrane filtration. The fractions displayed in vitro antioxidant, antihypertensive, and anti-tyrosinase activities as well as cell-based anti-inflammatory and anti-aging effects. In the future, the peptide fractions isolated from this rice byproduct could be directly exploited as health-promoting functional foods, dietary supplements, and pharmaceutical preparations. The suggested biotechnological process harnessing microbial bioconversion may represent a potential solution for many different protein-containing substrates currently treated as byproducts (or worse, waste) by the food industry.

Peptide Fractions Obtained from Rice By-Products by Means of an Environment-Friendly Process Show In Vitro Health-Related Bioactivities.

Recently, the isolation of new health-related bioactive molecules derived from agro-food industrial by-products by means of environment-friendly extraction processes has become of particular interest. In the present study, a protein by-product from the rice starch industry was hydrolysed with five commercial proteolytic enzymes, avoiding the use of solvents or chemicals. The digestion processes were optimised, and the digestates were separated in fractions with four different molecular weight ranges by using a cross-flow membrane filtration technique. Total hydrolysates and fractions were tested in vitro for a wide range of biological activities. For the first time rice-derived peptides were assayed for anti-tyrosinase, anti-inflammatory, cytotoxicity and irritation capacities. Antioxidant and anti-hypertensive activities were also evaluated. Protamex, Alcalase and Neutrase treatments produced peptide fractions with valuable bioactivities without resulting cytotoxic or irritant. Highest levels of bioactivity were detected in Protamex-derived samples, followed by samples treated with Alcalase. Based on the present results, a future direct exploitation of isolated peptide fractions in the nutraceutical, functional food and cosmetic industrial fields may be foreseen.

Feed-control development for succinic acid production with Anaerobiospirillum succiniciproducens.

The aim of this work was the development of a feed-control for a succinic acid production fed-batch process. The performed batch trials indicated a correlation between succinic acid production and base consumption pH control. Based on the metabolism of Anaerobiospirillum succiniciproducens, a theoretical correlation between base consumption and glucose feed was established and proved in cultivation trials. With the established fed-batch process, the succinic acid yield could be increased to 0.875 (g/g glucose) in comparison to batch processes (0.60) with similar glucose concentrations. Additionally, the results indicate that the osmolarity of the medium has a significant influence on succinic acid production.

Biomass recycling from a riboflavin cultivation with B. subtilis: lysis, extract production and testing as substrate in riboflavin cultivation.

Autolysis of riboflavin-producing B. subtilis can be induced by pH, lack of carbon source, and the buffer system. Stress factors like temperature shift or oxygen dearth enhance the autolysis process. After cultivation of a riboflavin-producing strain, the pH of the whole culture broth was adjusted to 6.5-7.5. At a temperature of 40 degrees C, autolysis started after 1 h. Adding a defined amount of commercially available endo- and exo-proteases enhanced both auto- and proteo-lysis. Optimization of endo- and exo-protease concentrations and of the time increased the degree of proteolysis. Additionally, the amount of DNA and Protein trapped in the riboflavin crystals could be significantly reduced by autolysis. After autolysis, the cultivation broth was centrifuged and the supernatant was cross-flow filtrated with a cut off of 10 kDa. Using this autolysate instead of yeast extract as a medium component for riboflavin production with B. subtilis, a riboflavin yield of 77% was obtained in comparison with the standard cultivation on yeast extract.