Effect of selected edible coatings of soy protein isolate, whey protein concentrate, carrageenan and alginate to extend shelf life of fresh-cut pears (Pyrus communis)

Overall quality and shelf life of fruits and vegetables is reduced by several factors including water loss, enzymatic browning, texture deterioration, senescence processes and microbial growth. In the case of fresh-cut fruits, these events are accelerated due to wastage of tissues inflicted by peeling, slicing and cutting. Edible coatings have been used to reduce the deleterious effect brought about by minimal processing. The semi-permeable barrier provided by edible coating is aimed to extend shelf life by reducing moisture and solutes migration, gas exchange, respiration and oxidative reaction rates, as well as suppress of physiological disorders on fresh-cut fruits. Edible films and coatings can also offer a possibility to extend shelf life of fresh-cut produce by providing a semi-permeable barrier to gases and water vapor, and therefore, reducing respiration, enzymatic browning. Their protective function may be also enhanced by addition of antimicrobials, antioxidants and nutrients additives. Edible composite coatings were prepared from soy protein isolate (SPI), whey protein concentrate (WPC), carrageenan and alginate were used in the formulations as edible coatings. Pear pieces were coated and color, browning index (BI), firmness and sensory evaluation were measured at 4̊c in 15 days. Also the results show that pear pieces coated with whey protein-based coatings had higher L* and lower b*, a* and BI–value (BI-value for WPC and SPI coating are 21.93±0.3, 24.83±0.8 respectively) the result showed that shelf life and firmness of pears with edible coating being extended during storage. Between coatings whey protein concentrate (WPC) showed better results.