Quality evaluation of commercial masmin of lakshadweep

Abstract- Masmin is a smoked dried tuna product that is both economically and nutritionally important to the people of Lakshadweep Islands. The objectives of the study were to determine the organoleptic, biochemical and microbial qualities of commercially produced masmin sold in various markets of Minicoy, Agatti and Andrott islands of Lakshadweep.

The proximate composition of masmin from various islands has shown that moisture content varied between 8.11 and 12.04%, protein between 76.66 and 80.69%, fat between 3.46 and 3.55% and ash between 6.35 and 6.74%. The data indicate that masmin is similar in composition to other dried fish products. Moisture content of masmin increased during storage on account of slight hygoscopicity of product and water vapour permeability of the packaging material (polypropylene) used. This resulted in a significant increase in water activity, even exceeding the maximum recommended value of 0.65, particularly in the case of Andrott Island.
The increased water activity would have encouraged both bacterial and fungal growth as indicated by the increases in total plate count and total fungal count of masmin samples of all the islands during storage. Bacterial activity would have resulted in the production various nitrogenous compounds as indicated by the increase in total volatile nitrogen content of the samples during storage. Since these compounds are basic in nature the pH of the products also showed an increase. Thiobarbituric acid value was low, being only 0.5-1.02 mg malonaldehyde/ kg initially, and the increase during storage was too low to impart any rancid odour.

The sensory evaluation scores, viz., appearance, odour, colour, texture and and overall acceptance, for the products of all the three islands showed a significant decrease during storage. The scores for all parameters were initially high for samples from all the islands, being in the range 3.5 - 4.0 out of a maximum of 5, indicating that the products were all of good quality in the beginning. Increased microbial activity that resulted in the production of various breakdown products possibly is responsible for the quality loss.

During processing of masmin fungi of natural origin are encouraged to grow for imparting a special flavour to the product. However it is likely that some toxigenic fungi may occur in the product. Out of 22 isolates obtained over 70% belonged to the genus Aspergillus and the rest were constituted by the genera Penicillium, Fusarium and the yeast Candida. Candida sp. was isolated from a masmin sample of Minicoy Island. One isolate, identified as Aspergillus, from a sample from Andrott was found to produce aflatoxin, which was detected by the culture method and confirmed by the TLC method.

Based on the study it may be inferred that the masmin available in the markets of Lakshadweep Islands are in general of good quality. However, significant variations in quality were seen between islands and significant quality loss during storage. Occurrence of aflatoxigenic fungi in the market samples causes concern.