Microbial and chemical changes during the spontaneous ensilage of grape pomace

Abstract

Pilot scale fermentations with grape pomace from two different wineries were investigated during the 24 weeks of the ensiling period, along with laboratory scale experiments in which the environmental temperatures were held constant at 20, 25, 30 and 35 °C. During this period, yeast and lactic acid bacteria (LAB) counts were made, after which the identity of both groups of organisms was studied, as were the major microbial metabolites present. Major microbial and chemical alterations occurred during the first 3 weeks of ensilage, leaving a more stable product differing significantly from the initial substrate. The results obtained indicated that after initial growth, yeast and LAB populations undergo progressive inactivation at environmental temperatures above 20 °C, although LAB seem to adjust better to this specific, post‐fermentation environment. Homofermentative species of Lactobacillus were the dominant LAB. The initial yeast flora of non‐Saccharomyces species was replaced by a typical wine yeast flora, i.e. predominantly Saccharomyces cerevisiae. At the chemical level, major alterations were due to an alcoholic fermentation and a malolactic conversion within the first 3 weeks.

A comparative analysis of microflora during biofilm development on grape seeds exposed to methanol in a biofilter

“…One possible explanation for these results is the high microbial density found mainly in the upper zone of the biofilter column and the need for space. It is reasonable to hypothesize that the moisture content, temperature, and methanol favored the development of these bacteria and yeasts (De Pina and Hogg 1999;Delhoménie and Heitz 2005), whereas the growth of filamentous fungi was inhibited.…”

Influence of moisture content on microbial activity and silage quality during ensilage of food processing residues

“…Bacteria were isolated from fresh TP using an approach adapted from de Pina and Hogg [14]. Samples of 30 g fresh TP were homogenized for 10 min in a blender at low speed with 270 mL 1/4 strength Ringer solution.…”

Influence of Temperature and Drying Time on Extraction Yield of Phenolic Compounds from Grape Pomace Variety “Portogizac”

“…Grape pomace has so far been investigated as a fertilizer or soil conditioner [10][11][12][13] , as biomass for biofuel production [14][15][16] and as animal feed [17][18][19][20] . Wet grape pomace is a highly perishable material subject to uncontrolled microbial spoilage owing to its high moisture content (~60 % wb ) and water activity.…”