Effect of culture conditions on production of butter flavor compounds by Pediococcus pentosaceus and Lactobacillus acidophilus in semisolid maize-based cultures

Two series of 120 h mixed cultures of Pediococcus pentosaceus MITJ-10 and Lactobacillus acidophilus Hansen 1748 were grown in semisolid maize-based media, applying an orthogonal factorial design in order to establish the most adequate parameters to get compounds related to butter-like flavor. Conditions of maize pre-treatment established in the first series were hot lime-treatment for 20 min, grinding and sieving to 0.0165 in., partial defatting and cooking for 25 min. While the culture conditions established for the second series were the addition of yeast extract (0.2% w/w), and culture starting with 2x10(6) CFU g(-1) and a ratio of P. pentosaceus and L. acidophilus, 3:1. The fermentation profile was studied in a last culture. Lactic acid bacteria (LAB) prevailed over the native microorganisms, with a specific growth rate of 0.47 h(-1). Diacetyl production correlated (r2=0.9972) with the 12 h exponential growth phase of LAB. The concentration of diacetyl at that time was 779.56 mg kg(-1). The contents of lactic acid and volatile fatty acids were low at 12 h, 665 and 1312 mg kg(-1), respectively. During the long stationary phase, they increased up to 4800 and 1886 mg kg(-1), respectively. This procedure might be useful to prepare naturally aromatized raw materials for the food industry.     

Angiotensin I-converting enzyme-inhibitory peptide fractions from albumin 1 and globulin as obtained of amaranth grain

A number of biopeptides promoting health benefits have been isolated from food-protein hydrolysates and can be released during enzymatic digestion. Antihypertensive peptides can be part of protein fractions from amaranth grain. The objective of this work was to obtain ACE-inhibitory peptide fractions from albumin 1 and the globulin of amaranth (Amaranthus hypochondriacus) grain. Albumin 1 and globulin were hydrolysed with alcalase; hydrolysis was monitored by proteolytic degradation and by ACE-inhibitory activity. The highest ACE-inhibitory activity was 40% and 35% as obtained after 18 and 15 h hydrolysis for albumin 1 and globulin, respectively. Further separation and purification of the ACE-inhibitory peptide fractions were carried out by gel filtration and C₁₈ RP–HPLC. The IC₅₀ was 0.35 ± 0.02 mg/ml for albumin 1 peptide fraction and 0.15 ± 0.03 mg/ml for globulin peptide fraction. Albumin 1 peptide fraction showed an competitive mode of ACE inhibition, whereas the globulin peptide fraction was competitive. The globulin peptide fraction may have one of the most active naturally-occurring ACE-inhibitory peptides.