Optimization of the combined effect of whey protein concentrate, maltodextrin and rosemary essential oil on the bacterial total count of tilapia fillets during cold storage

In this study, the combined effect of whey protein concentrate, maltodextrin and rosemary essential oil on the microbial properties of tilapia was investigated and optimized by Response Surface Methodology. after preparing fish fillets, according to the software plans, 18 solutions including 10, 5 and 15% w/w of whey protein concentrate, 15, 20 and 25% w/w of maltodextrin and 1, 3 and 5% v/w rosemary essential oil were prepared. Fish fillets were coated by immersing in solutions and then were refrigerated at 4℃. After six days, coated samples were removed from refrigerator and microbial contamination was evaluated. Based on the obtained data from microbial counts (psychrophilic bacteria), the best protective solution was produced by mixing moderate amounts of whey protein concentrate (about 10% w/w) with the highest percentages of rosemary essential oil (5% v/w). In case of mesophilic bacteria, the best protective effect was observed when the coatings solution was included of maximum amount of maltodextrin and whey protein concentrate (25 and 15% w/w) and rosemary essential oil (5% v/w).