Moisture Sorption Characteristics and Storage Study of Grape Seeds Flakes

Abstract

The current scientific research is focused on the sorption isotherms, monolayer moisture content and storage study of full-fatted grape seeds flakes (FGSF) of different grape variety locally grow in Bulgaria (Mavrud, Cabernet Sauvignon, Syrah, Merlot, Dimyat and Sauvignon Blanc). To determine the sorption characteristics of FGSF, we are used a static gravimetric method of saturated salt solution and relative humidity from 0.11 to 0.90 at three different temperatures – 10, 25 and 40°C. In the condition of constant water activity and increasing temperatures, the sorption capacity of the product decrease. We are recommend the modified Henderson model for description of sorption isotherms of FGSF. The monolayer moisture content values are obtained by linearization of Braunauer-Emmett-Teller (BET), in the range of Mmads = 2.32 ÷ 3.41, Mmdes = 2.59 ÷ 3.68. The three months storage study of samples was monitored at moisture value reduced to a value corresponded to the calculated monolayer moisture content. FGSF was packed in a co-extruded barrier film with copolymer covering for heat sealing, in the conditions for storage - temperature 18 ÷ 25°C and relative humidity 75 ÷ 85%. No living cells of pathogenic organisms (Escherichia coli, Staphylococcus aureus and Salmonella spp.) or apparent molding were detected. The flour particle size has not changed either.