Mathematical modeling for ethanol, methanol and acetaldehyde generation through Mexican carignane grape (Vitis vinifera) vinification process

Wine is a worldwide known beverage, and even though its consumption has been associated with the reduction of heart diseases and the extent of lifespan, it also has compounds that might cause adverse effects on human health such as methanol and acetaldehyde. The aim of this study was to determine the effect of time, temperature, and pectic enzymes over wine methanol and acetaldehyde concentrations during vinification. Three temperatures (20, 30, and 35 °C) and three pectic enzyme concentrations (0, 9, and 18 mL/Kg) were tested, letting fermentation to stop due to sugar depletion. Both, metanol and acetaldehyde were quantified throughout the fermentation process. Temperature reduced metanol production, observing the lowest metanol concentration (53.543 ± 3.267 mg/100 mL of wine) at 35 °C in the absence of pectic enzyme. Acetaldehyde was not affected by these variables. Alcohol, metanol, and acetaldehyde concentrations were adjusted to mathematical models with high correlations.

Study of the Major Pathogens That Lead to Apple Fruit Decay During Storage

Different pathogenic fungi (e.g. Penicillium spp., Monilinia fructigena, Venturia inaequalis, Glomerella cingulata, Diaporthe eres etc.) can cause apple rot by producing pectic enzymes that break down apple pectin to expose the nutrients of the cells to the fungi. This study aimed to identify the pathogens that lead to the degradation of apples from five different varieties (‘Granny Smith’, ‘Topaz’, ‘Imperial Gala’, ‘Jonagold’ and ‘Golden Reinders’) and also the incidence of those pathogens under different treatment conditions. The results reveal different frequent attacks on distinct varieties ranging from 5 to over 50%. Of the pathogens that infect and occur in vegetation and deposit it can be seen that Venturia inaequalis has been identified in all varieties in most test variants. The highest frequency was recorded in the variant where during the vegetation period no treatments with fungicides against apple diseases were applied. Of the pathogens that infected and appeared during storage, isolated on the fruits, only Fusarium spp. and Penicillium spp. had a higher frequency. Applying treatments during the growing season reduced the rotting attack degree of apple fruits during storage. The best response to rot attack in the warehouse was ‘Topaz’ and ‘Jonagold’, the attack degree ranged between 0.3 and 10% on treated variants. By applying chemical treatments, the spectrum and the share of pathogens that lead to fruit degradation is different. This means that chemical treatments must be chosen depending on the nature of the pathogens and the apple variety.

Solid-state fermentation for production of Pectic enzymes by Aspergillus niger

The production of Pectic enzymes by Aspergillus niger was studied under solid state fermentation (SSF). The effect of fermentation condition such as substrate concentration, inoculum volume, incubation time, moistening agent, inducers and organic and inorganic nitrogen sources was studied for enzyme production. Culture conditions were optimized for maximal yield of enzyme. The solid substrate wheat bran was most suitable for pectic enzyme production under SSF. Enzyme production was found maximum after 10 days of incubation. Lactose was found to be most effective as inducer. Gelatin as organic nitrogen source and ammonium nitrate as inorganic nitrogen source yielded high enzyme titres.

Comparison of some commercial pectic enzyme preparations applicable in wine technology

The preparations of pectic enzymes are used for a more efficient extraction of desirable red grape pigments and other phenol compounds which are bound in plant cells and can be faster released by the action of pectic enzymes. Moreover, they shorten the time of maceration, settling, and filtration. The results of our experiments gives a comparison of the efficiency of preparations applicable in wine technology. The best preparation was Trenolin Rot followed by Vinozym G that could shorten the time of prefermentation to about 3 days thanks to a more intensive extraction of red grape pigments. By using the enzyme preparations Gammapect AWP and Ovopres, the time of filtration was ten times shorter. Compared to the control sample, the speed of desliming was threefold and twofold faster, respectively, for Gammapect AWP and Gammapect W2L.