Effect of combined preservation techniques on the stability and microbial quality and retention of anthocyanins in grape pomace stored at low temperature

Abstract

Studies were carried out with an objective to assess the effect of various post harvest treatments with chemical preservative, ionizing radiation doses and low temperature (LT) storage on the storability and the microbial quality of the grape pomace and retention of anthocyanins in it. The grape pomace collected after processing of fully matured grape berries (var.Bangalore blue) was treated with 0.1% sodium benzoate(0.1% SB), packed and sealed in LDPE film pouches and exposed to γ-irradiation(0, 2, 4 and 6 kGy) and stored along with untreated control at LT (4±1°C, 90-95% RH)conditions. During storage, changes in physico-chemical and microbial quality attributes of these treated grape pomace were recorded. Among the treatments, combination of 0.1% sodium benzoate and 2.0 kGy dose of γ-irradiation (0.1% SB +2.0 kGy) was found to be more effective in improving the storability of grape pomace and in retention anthocyanins (34.70 mg/100 g) during storage. The storage life of above treated grape pomace stored at LT could be extended up to 16 days as compared to 8 days of control grape pomace (31.8 mg/100 g). Results on microbiological studies indicated that 0.1% SB +2.0 kGy reduced the total aerobic bacterial count (1.4 log CFU/g) and the yeast and mould count (1.6 log CFU/g) in the treated grape pomace during 16 days of storage as compared to the total aerobic bacterial count (6.5 log CFU/g) and the yeast and mould count (6.3 log CFU/g) in control. Sodium benzoate and low irradiation (0.1% SB +2.0 kGy) was significant in controlling the multiplication of coliforms in grape pomace during LT storage and thus finds potential for commercial application in ensuring the microbiological safety and quality of grape pomace during its bulk storage at low temperature (4±1°C; 90-95% RH) conditions. This preservation method could be used by the wine making industries for bulk storage of grape pomace after processing of colored grapes during peak harvesting season for further end uses.

Applications of Wine Pomace in the Food Industry: Approaches and Functions

“…The presence of microorganisms in wine pomace has been poorly studied. Available data indicate relatively low values of spoilage microorganisms, with counts of total aerobic mesophilic bacteria (TAMB) ranging between 3 and 6 logs colony forming units (CFU) per gram and loads between 3 and 6 logs CFU/g of yeasts and molds (Ayed and others ; Augustine and others ; Özlem and others ).…”

“…Different acids (sulfuric, tartaric, or phosphoric acids) or sulfites can also be sprayed over pomace in order to avoid wine pomace degradation (Silva and Malcata ; Ayed and others ). Gamma‐irradiation in combination with other synthetic preservatives such as sulfites (Ayed and others ) and sodium benzoate (Augustine and others ) has also been proposed to increase its shelf‐life. However, different drying methods are the most common ways of processing wine pomace.…”

Effect of Extraction and Processing Conditions on Anthocyanins of Barberry

“…Irradiation at low doses may increase MAC by increasing activity of catechol oxidase which is responsible for creating anthocyanin units (Augustine et al . ).…”

“…In addition to gamma irradiation increases decomposition of cell membranes which can increase the yield of extraction (Augustine et al . ).…”

Effect of different physicochemical de-tartration methods on red grape juice quality

“…They concluded that MAP, honey solution dip or their combination significantly maintained the general quality of minimally processed grape by delaying quality loss and berry decay. Augustine et al (2011) carried out a study to assess the effect of various combined post harvest treatments with chemical preservative, ionizing radiation doses and low temperature (LT) storage on the storability and the microbial quality of the grape pomace and retention of anthocyanins. The results showed that combination of sodium benzoate and γ-irradiation (0.1 % SB +2.0 kGy) was effective in improving the storability of grape pomace and in retention anthocyanins during storage.…”