Drying and storage characteristics of golden apple snail (Pomacea spp.)

Drying and storage characteristics of golden apple snail (GAS) as a non-conventional food, fertilizer and feedstuff were established in this study. Physical and thermal properties of GAS whole meat, crushed meal, ground dried meat, and ground dried meal including physical dimensions, shrinkage, 1000 particle weight, bulk density, angle of repose, angle of friction, specific heat, thermal conductivity, and thermal diffusivity, were likewise experimentally determined at several moisture levels. Empirical and semi-empirical models for drying GAS whole meat and crushed meal were developed using the Response Surface Analysis considering the effect of drying air temperature, air velocity, and loading capacity on final moisture content, drying rate, rehydration ratio, crude protein content, aroma, color, dryness, brittleness, and the overall acceptability. The optimum drying conditions were determined at 97 deg C, 0.31 m/s, and 11.5 kg/sq m for whole meat and 94 deg C, 0.3 m/s, and 12 kg/sqm for crushed meal. The modified Page equation best described the thin-layer drying of whole meat and crushed meal. Results of the physic-chemical and microbiological analyses for the processed dried GAS whole meat and crushed meat have met the specification standards as prescribed for commercially dried food and/or feedstuff in the country. Moisture sorption isotherm models that best describe both the desorption and adsorption paths of whole meat, crushed meal, ground meat and ground meal were developed at 4, 18, 28 and 60 deg C with relative humidity ranging from 18 to 94%. An hysteresis effect was observed for GAS whole meat and crushed meal. The phenomenon of caking was observed at when the moisture content reaches 25% and 9% moisture content, dry basis, for ground meat and ground meal, respectively. Bacillus sp. and Aspergillus sp. were the identified dominant microorganisms causing early spoilage on the storage of fresh whole meat and crushed meal. Results of the study can be used in the design of process equipment particularly on GAS drying, storage and handling. Moreover, these results can serve as sound bases in developing the standard protocol for golden apple snail processing into food, feed, and fertilizer material.