DEVELOPMENT OF ALMOND GUM/ALGINATE COMPOSITES TO ENHANCE THE SHELF-LIFE OF POST-HARVEST SOLANUM LYCOPERSICUM L

Abstract

Almond Gum/alginate composite (AG/AL) composites namely A1, A2 and A3 were prepared and their physicochemical properties were evaluated. The measured film thickness, moisture and solubility were indistinguishable among the films whereas water contact angle analysis shows that A2 (83.8±1.65) and A3 (86.2±3.19) film has high hydrophobicity than A1 (58.4±3.21). By increasing plasticizer concentration from 0.4% to 0.66%, elongation was increased from 30 to 53 % whereas tensile strength (3.16 to 1.90 Mpa) and water vapor transmission rate (WVTR) decreased from 212 to 160 g/m2/24hr. FT-IR analysis shows that the edible film has O-H, C-H, C=O and –COO functional groups and SEM analysis reveals that the prepared film has even surface due to the strong interaction between polymer and plasticizer. TGA results show major weight loss at 100°C, 190-220°C and 350°C-400°C due to the dehydration/decomposition of water molecules and carbon containing functional groups. Film solution was used as an edible coating in tomatoes and weight loss (WL), titratable acidity (TA), Total soluble solids (TSS), ascorbic acid content (AAC) and anti-microbial activity were determined. The WL analysis shows a significant delay in decay of coated tomatoes over 40 days of storage time whereas control tomatoes decayed on day 25. TA and TSS test confirms that the coating can significantly (P<0.05) prevent the acidity level of tomaotes. Furthermore, the AG/AL coating has great activity against E. coli, Bacillus subtilis, Enterococcus faecalis, Staphylococcus aureus. Therefore, the present study confirms that AG/AL has superior properties and potential as edible films or coating.