The research has been carried out to compare chitosan extracted from shrimp and crab shell waste by chemical method and to investigate its effect as a clarifying agent as well as preservative on the pineapple juice qualities. Chitosan has been derived from shrimp and crab shells by the standard chemical process consisting of three important treatments such as demineralization (2%HCl, 16hr), deproteinization (4% NaOH,20hr) and deacetylation (60% NaOH, 65ºC, 20hr). Physicochemical properties of chitosan derived from both the sources like fat binding capacity (FBC), water binding capacity (WBC), solubility, average molecular weight, ash content, moisture content and degree of deacetylation were studied. The degree of deacetylation and solubility were obtained as 76 and 65% for shrimp shell chitosan and 91 and 70% for crab shell chitosan, respectively. In a similar way, the WBC and FBC of shrimp and crab shells chitosan were found to be 445 and 260% and 360 and 210%, respectively. The average molecular weight of shrimp and crab chitosan was found to be very close to each other. smoother surface and nanofiber structures were observed from Microscopic analysis. Chitosan was added to pineapple juice as a clarifying agent at a concentration of 0.2, 0.4 and 0.6g/L. It was observed from the investigation that shrimp chitosan at a concentration of 0.6g/L was more effective at 28±2ºC than crab chitosan after 90 min of addition. Statistical analyses revealed that source of chitosan possess significant effect on the perceived sensory characteristics of juices when chitosan has been added at a range from 0.2 to 0.6 g/L of pineapple juice. Chitosan also inhibited the growth of some spoilage bacteria. The analyses showed that increases in chitosan concentration extended the quality of the pineapple juice significantly (0.05), increasing pH values range, reducing TSS value, enzymatic and non-enzymatic browning and controlling the spoilage during the storage time. This study showed that shrimp shell chitosan produces more brilliant juice than crab shell chitosan and hence can be used as a preservation as well as clarifying agent for better quality pineapple juices. for the preparation of chitosan and shrimp chitosan was more effective than crab chitosan as a preservative and clarifier on the quality of pineapple juice.
Key words: Chitosan, pineapple, juice, shrimp, crab
|
