Evolutionary timeline of a modeled cell.

A theoretical study of cell evolution is presented here. By using a toolbox containing an intracellular catalytic reaction network model and a mutation-selection process, four distinct phases of self-organization were unveiled. First, the nutrients prevail as the central substrate of the chemical reactions. Second, the cell becomes a small-world. Third, a highly connected core component emerges, concurrently with the nutrient carriers becoming the central product of reactions. Finally, the cell reaches a steady configuration where the concentrations of the core chemical species are described by Zipf's law.

Gastrointestinal metabolism and bioaccessibility of selected anthocyanins isolated from commonly consumed fruits.

There is uncertainty about the identity of digestive metabolites of anthocyanins because many are naturally present in foods and/or are formed from other phenolic compounds during the digestive process. Studies using pure anthocyanins are needed to clarify this uncertainty. In this study, selected anthocyanins were purified from common fruits and individually subjected to gastric and small intestinal digestion in vitro to determine their stability, metabolites generated and bioaccessibility. Anthocyanins were highly stable during the gastric phase of simulated digestion (p > 0.05). The recovery of anthocyanins decreased during the small intestinal phase of digestion (p < 0.05). Stability was dependent on anthocyanidin structure and type of glycation (p < 0.05). Gastric and gastrointestinal phases mainly contained anthocyanins as bioaccessible flavylium cations and chalcones. Expected anthocyanin metabolites (i.e., phenolic acids and phoroglucinaldehyde) were not detected in chyme. Deglycation of anthocyanins during simulated digestion was quite limited and the bioaccessibility of intact anthocyanins was very low (0.07-2.21%).

Comparative study of the banana pulp browning process of 'Giant Dwarf' and FHIA-23 during fruit ripening based on image analysis and the polyphenol oxidase and peroxidase biochemical properties.

This work presents a novel method to associate the polyphenol oxidase (PPO) and the peroxidase (POD) activities with the ripening-mediated color changes in banana peel and pulp by computational image analysis. The method was used to follow up the de-greening of peel and browning of homogenized pulp from 'Giant Dwarf' (GD: Musa AAA, subgroup Cavendish) and FHIA-23 (tetraploid hybrid, AAAA) banana cultivars. In both cultivars, the color changes of peel during the ripening process clearly showed four stages, which were used to group the fruit into ripening stages. The PPO and POD were extracted from pulp of fruit at these ripening stages, precipitated, and partially purified by gel filtration chromatography. Moreover, the pulp browning was digitally monitored after homogenization for a span time of up to 120 min. The browning level was higher for GD than FHIA-23 tissues. This fact correlated with an 11.7-fold higher PPO activity in the GD cultivar, as compared with that of FHIA-23. POD activity was 8.1 times higher for GD as compared that that of FHIA-23.

Effects of pectin on lipid digestion and possible implications for carotenoid bioavailability during pre-absorptive stages: A review.

Pectin, an abundant polysaccharide in the human diet, has structural characteristics and functional properties that are strongly dependent on the food matrix (e.g., origin, type, cultivar/variety, ripening stage, style and intensity of processing). These polysaccharides have a strong effect on lipid digestion, which is required for the liberation of carotenoids from emulsified lipid droplets in the gastrointestinal content and for the formation of micelles, in which the carotenoids must be incorporated before absorption. Only micellarized carotenoids can be absorbed and subsequently exert protective effects on human health. The alteration of lipolysis by pectin can occur through several mechanisms; however, they have not been linked directly to carotenoid micellarization. This paper provides an overview of the effects of the properties of pectin on the ion concentration in the digestive content, the viscosity of the digestive medium, the properties of the lipid droplet surfaces and lipase activity and analyzes the impact of these events on lipid digestion and subsequent carotenoid micellarization.

Lactobacillus plantarum WCFS1 ß-Fructosidase: Evidence for an Open Funnel-Like Channel Through the Catalytic Domain with Importance for the Substrate Selectivity.

ß-Fructosidase, a glycoside hydrolase of a biotechnologically important strain, was studied for its biochemical, physicochemical, and three-dimensional structure characteristics. This enzyme was heterologously expressed in Escherichia coli as a C-terminal His-tagged protein (SacB). ß-Fructosidase catalyzes the cleavage of glycoside bonds toward certain carbohydrates with ß-fructofuranosyl linkages; however, SacB exhibited selectivity toward sucrose and an optimum activity at pH 6.0-6.5 and 37 °C. In such optimum enzymatic activity conditions, the SacB was commonly observed as a monodisperse protein by dynamic light scattering (DLS). As ß-fructosidase belongs to glycoside hydrolase family 32 (GH32), a ß-sandwich and a five-bladed ß-propeller domain are typical predicted folds in its structure. Docking and molecular dynamic simulations revealed for the first time a funnel-like channel perfectly exposed in the ß-propeller domain of the Lactobacillus plantarum ß-fructosidase (this allows the interaction between its entire catalytic triad and substrates that are larger than sucrose). In contrast, SacB showed a closed central tunnel collaterally induced by its His-tag.

Identification and Functional Characterization of a Fructooligosaccharides-Forming Enzyme from Aspergillus aculeatus.

Although fructosyltransferases from Aspergillus aculeatus have received a considerable interest for the prebiotics industry, their amino acid sequences and structural features remain unknown. This study sequenced and characterized a fructosyltransferase from A. aculeatus (AcFT) isolated by heat treatment of Pectinex Ultra SP-L. The AcFT enzyme showed two isoforms, low-glycosylated AcFT1 and high-glycosylated AcFT2 forms, with similar optimum activity at 60 °C. The purified heat-resistant AcFT1 and AcFT2 isoforms produced identical patterns of fructooligosaccharides (FOS; kestose, nystose and fructosylnystose) with a notable transfructosylation capability (~90 % transferase/hydrolase ratio). In contrast, the pI and optimum pH values exhibited discrete differences, attributable to their glycosylation pattern. Partial protein sequencing showed that AcFT enzyme corresponds to Aspac1_37092, a putative 654-residue fructosyltransferase encoded in the genome of A. aculeatus ATCC16872. A homology model of AcFT also revealed the typical fold common to members of the glycoside hydrolase family 32 (GH32), with an N-terminal five-blade ß-propeller domain enclosing catalytic residues D60, D191, and E292, linked to a C-terminal ß-sandwich domain. To our knowledge, this is the first report describing the amino acid sequence and structural features of a heat-resistant FOS-forming enzyme from A. aculeatus, providing insights into its potential applications in the prebiotics industry.

Effect of the perforation level of recycled-LDPE bags on the modification of the atmosphere development, bioactive compounds content, and other qualities of Jalapeño peppers during storage.

The impact of modified atmosphere packaging on the content of selected bioactive compounds and other quality attributes of Jalapeño peppers has not been well studied. In this study, Jalapeño peppers were packed in low-cost bags (composed of recycled-LDPE) that had been perforated at several levels (0-4 holes). Packages were stored at 7 °C for 6 weeks. Samples of unpacked peppers were stored at 23 and 7 °C and were used as control groups. The quality of the peppers and the gas composition inside of the packages were evaluated during storage. The best modified atmosphere was obtained with unperforated bags. Significant loss of weight and firmness were prevented by packaging. The loss of weight and firmness were 20.2-82.6 and 32-100 % in unpacked peppers. Low levels of fermentative metabolites accumulated in packed peppers in unperforated bags and in bags with 1 perforation. The tristimulus color and the bioactive compounds content (phenols, ascorbic acid, ß-carotene, and capsaicinoids) remained unchanged in packed peppers. These quality attributes changed gradually in peppers that were stored at 23 °C. The tested bags represent a cost-effective alternative to preserve the quality of intact Jalapeño peppers.

The effect of ripening, heat processing and frozen storage on the in vitro bioaccessibility of capsaicin and dihydrocapsaicin from Jalapeño peppers in absence and presence of two dietary fat types.

To date, there is no information in the literature regarding the bioaccessibility of capsaicinoids from natural sources. The effect of ripening and heat-processing on the in vitro bioaccessibility of capsaicin and dihydrocapsaicin was studied in the absence and presence of two dietary fat types. The capsaicinoid bioaccessibility was also studied during the frozen storage of peppers for 6 months. Fresh green peppers showed the highest capsaicinoid bioaccessibility, as compared with that of other experimental groups. The bioaccessibility of capsaicinoids from green peppers decreased as the intensity of heat treatment increased. The dietary fat increased the bioaccessibility of capsaicin and dihydrocapsaicin in digestions with red peppers, especially that of dihydrocapsaicin. The bioaccessibility of capsaicinoids was altered by frozen storage. The Caco-2 cells incorporated capsaicin and dihydrocapsaicin (8.4% and 10.9%, respectively) but they were probably metabolized by cells.

Effect of ripening and heat processing on the physicochemical and rheological properties of pepper pectins.

Water-, chelator-, and alkali-soluble pectins were isolated from raw and heat-processed Jalapeño peppers (green and red) and their physiochemical and rheological properties were determined. The yield, tristimulus color, degree of methyl esterification, monosaccharide composition, molecular weights distribution, and protein content depended on ripening and heat processing. The viscosity properties of pectins were independent of ripening. The water-soluble pectin was the most abundant pectin. Pectins from grilled peppers showed the lowest L* values. The alkali-soluble pectin showed the highest protein content. The content of xylose, rhamnose, and mannose in pectins was highly altered by tested factors. The degree of methyl esterification of pectins ranged from 26.8 to 91.6%. The peak Mw of the main fraction of tested pectins was sequentially reduced by ripening and heat processing. Pectins from raw peppers showed the best viscosity properties.

Antioxidant activity and content of chlorophylls and carotenoids in raw and heat-processed Jalapeño peppers at intermediate stages of ripening.

Jalapeño peppers at intermediate ripening stages (IRS) are typically discarded at the packinghouse because they are not demanded for fresh consumption or industrial processing. These peppers have been scarcely studied in terms of pigment composition and bioactivity. In this study, the profile of pigments (carotenoids and chlorophylls) and antioxidant activity were determined in raw and heat-processed Jalapeño peppers at three IRS (brown, 50% red, and 75% red). Peppers contained 64 different pigments. Chlorophylls were the most abundant pigments in raw brown peppers while capsanthin was the most abundant at the other IRS. The content of most pigments decreased due to heat treatments. Several pheophytins and cis isomers of carotenoids were generated by heat processing. Boiling and grilling consistently decreased and increased the antioxidant activity of peppers, respectively. Tested peppers showed a more complex/abundant pigment content and higher antioxidant activity than those typically reported for green and red peppers.

Effect of ripening, heat processing, and fat type on the micellarization of pigments from jalapeño peppers.

Raw and heat-processed (boiled and grilled) jalapeño peppers at three intermediate ripening stages (brown, 50% red, and 75% red) were digested in vitro without fat and in the presence of soybean oil (SO) or beef tallow (BT), and the micellarization of their lipid soluble pigments (LSP) was measured. The micelles from digestions with brown, 50% red, and 75% red peppers contained up to 27, 35, and 29 different LSP, respectively. Boiling and grilling decreased the micellarization of LSP from brown peppers, whereas the opposite was observed with 75% red peppers. Heat processing did not clearly affect the micellarization of LSP from 50% red fruits. The impact of fat on LSP micellarization was ripening-dependent, but the micellarization of the less polar carotenoids was always increased by SO or BT. This positive effect of fat was higher with SO than with BT.

Physical attributes and chemical composition of organic strawberry fruit (Fragaria x ananassa Duch, Cv. Albion) at six stages of ripening.

Organic strawberry fruits (Cv. 'Albion') were harvested at six different ripening stages and evaluated for physical and chemical parameters. Biometrical characteristics and moisture content did not change significantly during ripening. Total soluble solids, pH and colour development increased while titratable acidity and fruit firmness decreased 14.7% and 91%, respectively. Fructose, glucose, and sucrose followed similar tendencies. Final contents of these sugars were 2323.4, 1988.5, and 1578.4 mg/100 g. Citric, malic, and ascorbic acids followed a descending, irregular, and increasing tendency during ripening, respectively. Final contents of these acids were 822.8, 245.8, and 78.1 mg/100 g. Total anthocyanins content (TAC) increased during ripening, while the opposite was observed for total phenolic content (TPC). TAC and TPC in ripe fruit were 56.4 mg/100g and 196 mg gallic acid equivalents (GAE)/100 g. Twenty eight phenolic compounds, mainly glycosides, were identified and quantified by HPLC-DAD-MS analysis. The concentration of these compounds was ripening dependent.

Effect of heat processing on the profile of pigments and antioxidant capacity of green and red jalapeño peppers.

Raw and heat-processed jalapeño peppers (green and red) were evaluated for their pigment profile and antioxidant capacity. Sixty-seven pigments were separated and characterized by HPLC-DAD-MS, including carotenoids (isomers and esters), chlorophylls, and pheophytins. The distinctive characteristics of this pepper genotype were the presence of antheraxanthin monoesters, zeaxanthin monoesters, mutatoxanthin diesters, and a higher content of free capsanthin relative to the mono- and diesterified forms. Chlorophyll a and free all-trans-lutein were the major pigments in raw green peppers, whereas free all-trans-capsanthin was the most abundant pigment in raw red peppers. Twelve compounds were generated by the heat treatments, mainly pheophytins and cis isomers of carotenoids. Heat treatments affected differentially the concentration of individual pigments. Red peppers showed a higher antioxidant capacity than green fruits. Heating caused minor changes in the antioxidant capacity of peppers.