In vitro bioaccessibility of amino acids and bioactive amines in 70% cocoa dark chocolate: What you eat and what you get.

Chocolate is an important source of free bioactive amines and amino acids which play important roles in human health. Considering the limited information on the bioaccessibility of these compounds from chocolate, the objective of this study was to characterize their profiles and bioaccessibility in 70% cocoa dark chocolate through in vitro simulation of oral, gastric and intestinal digestions. Seven amines were detected; polyamines were predominant before in vitro digestion, whereas tyramine, cadaverine and spermidine after digestion. All amines showed high bioaccessibility with slight influence of digestive enzymes. Amines increased after gastrointestinal digestion: tyramine (13-fold), tryptamine (9-fold), others (2.4-4.2-fold) and histamine appeared. All amino acids, GABA and ammonia were detected in chocolate, and their contents increased after in vitro digestion due to digestive enzymes (4.6, 2.8 and 2.1, respectively). Dark chocolate protein is a good source of tryptophan, phenylalanine + tyrosine, isoleucine, histidine, but limiting for lysine, leucine, and threonine.

In vitro digestion of spermidine and amino acids in fresh and processed Agaricus bisporus mushroom.

Mushrooms are significant sources of amino acids and bioactive amines; however, their bioaccessibility can be affected by processing and during in vitro digestion. Fresh Agaricus bisporus mushroom was submitted to cooking and canning and samples were submitted to in vitro gastric and gastric-intestinal digestions. An UHPLC method was used for the simultaneous determination of 18 free amino acids, 10 biogenic amines and ammonia in the samples. Fresh mushroom contained 14 free amino acids, with predominance of alanine and glutamic acid; spermidine was the only amine detected; and ammonia was also detected. Spermidine levels were not affected by cooking, but there was a significant loss (14%) after canning. Spermidine levels were not affected by the in vitro gastric and intestinal digestion, suggesting full bioaccessibility. There was a significant decrease on total amino acids levels after cooking and canning, with higher losses for aspartic and glutamic acids in cooked and for aspartic acid and valine in canned mushrooms. After the in vitro gastric and intestinal digestions, the total levels of amino acids increased and two additional amino acids (arginine and methionine) were detected. During in vitro digestion many of the amino acids were released mainly in the intestinal phase. After in vitro digestion, amino acids per gram of protein of mushrooms are adequate for most FAO amino acid pattern for adults. Multivariate analysis confirmed that protein hydrolysis in processed mushrooms is higher in intestinal phase. Bioaccessibility data for spermidine in A. bisporus is a novelty and increase the value of this food.

Ficin: A protease extract with relevance in biotechnology and biocatalysis.

Due to the problems raised by the use of animal or microbial recombinant proteases, the use of proteases from vegetable origin is becoming increasingly popular.. Among them, sulfidryl proteases have a special interest. Ficin is an outstanding example of this kind of proteases. This paper aims to be to make a comprehensive review of the recent uses of this enzyme, including for example protein hydrolysis, the production of bioactive peptides and antibodies fragments (researchers point that ficin results are more reproducible than using other proteases), meat tenderization, milk coagulations in cheese making or peptide synthesis. Efforts to get industrial immobilized biocatalysts of the enzyme will be also described. The review shows the huge potential and brilliant prospect that this enzyme can have in the near future.

Preparation, functionalization and characterization of rice husk silica for lipase immobilization via adsorption.

Silica has been extracted from rice husks via a simple hydrothermal process and functionalized with triethoxy(octyl)silane -OCTES (Octyl-SiO2) and (3-aminopropyl)triethoxysilane - 3-APTES (Amino-SiO2), with the aim of using it as support to immobilize lipase from Thermomyces lanuginosus (TLL) via adsorption. The supports have been characterized by particle size distribution and elemental analyses, XRD, TGA, SEM, AFM and N2 physisorption so as to confirm their functionalization. Effect of pH, temperature, initial protein loading and contact time on the adsorption process has been systematically evaluated. Maximum immobilized protein loading of 12.3 ± 0.1 mg/g for Amino-SiO2 (5 mM buffer sodium acetate at pH 4.0, 25 °C and initial protein loading of 20 mg/g) and 21.9 ± 0.1 mg/g for Octyl-SiO2 (5 mM buffer sodium acetate at pH 5.0, 25 °C and initial protein loading of 30 mg/g) was observed. However, these biocatalysts presented similar catalytic activity in olive oil emulsion hydrolysis (between 630 and 645 U/g). TLL adsorption was a spontaneous process involving physisorption. Experimental data on Octyl-SiO2 and Amino-SiO2 adsorption were well-fitted to the Langmuir isotherm model. It was also investigated whether these biocatalysts could synthesize cetyl esters via esterification reaction. Thus, it was found that cetyl stearate synthesis required 100-110 min of reaction time to attain maximum conversion percentage (around 94%). Ester productivity of immobilized TLL on Amino-SiO2 was 1.3-3.1 times higher than Octyl-SiO2.