Grape pomace treatment methods and their effects on storage

Abstract

Introduction. Grape pomace is the most important by-product of winemaking that can be used as an additional raw material. There is a need for an optimal storage technology so that pomace can be further processed to obtain new types of products. We aimed to study the effect of grape pomace treatment on its microflora.
 Study objects and methods. We identified and quantified microflora on the fresh and one-month-stored pomace samples from white and red grape varieties. The samples were exposed to conventional drying at 60–65°C, infrared drying at 60–65°C, as well as sulfitation with sulfur dioxide and sodium metabisulfite.
 Results and discussion. The pomace microflora can be considered a microbial community. Almost all the samples stored for one month in an open area contained Saccharomyces cerevisiae yeasts, higher concentrations of filmy yeasts of the Candida, Pichia, Hansenula, Hanseniaspora/Kloeckera, and Torulaspora genera, as well as conidia of Mucor, Aspergillus niger, and Penicillium molds. Prevalent bacteria included acetic acid (mainly Acetobacter aceti) and lactic acid (Lactobacillus plantarum, Pediococcus, Leuconostoc) bacteria. These microorganisms significantly changed concentrations of volatile and non-volatile components, decreasing total polysaccharides, phenolic compounds, and anthocyanins 1.7–1.9, 3.7–4.0, and 4.0–4.5 times, respectively. The contents of micromycetes and bacteria in the one-month-stored samples were significantly higher than in the fresh pomace. Predrying and sulfitation decreased bacterial contamination, but to a lesser extent compared to micromycetes.
 Conclusion. Long-term storage spoiled pomace, leading to significant changes in its chemical composition. Sulfitation reduced microorganism growth during storage, but did not provide long-term preservation (over a month), while pre-drying at 60–65°C promoted longer storage.

Winemaking: “With One Stone, Two Birds”? A Holistic Review of the Bio-Functional Compounds, Applications and Health Benefits of Wine and Wineries’ By-Products

“…Due to these reasons, dehydration of wet grape pomace has been proposed as an essential procedure prior to any subsequent application. Many conventional process techniques have been suggested, such as infrared drying, freeze drying and gamma irradiation [318][319][320]. Furthermore, non-conventional extraction methods such as ultrasound, supercritical fluid extraction and pulsed electric fields have also been brought up, only to be limited by high initial costs and integrations.…”

Market Diversification and Competitiveness of Fresh Grape Exports in Peru

“…Market diversification is achieved through the penetration of new markets, the development of derivative products, and the promotion of innovative [11] and sustainable practices in viticulture and processing. However, effective and resilient diversification faces intricate challenges such as the volatility of the international market, tariff and non-tariff barriers, growing environmental awareness, and demands for quality and food safety standards [12], as well as logistical issues in product conservation [13]. Therefore, a scientific and rigorous approach is required to analyze the complex reality of fruit, specifically fresh grapes, and contribute to the design and implementation of holistic and context-sensitive strategies to strengthen market diversification and consolidate competitiveness in international trade.…”