QUALITY CHARACTERISTICS OF WASH-FREE RICE AND EVALUATION OF ITS STORAGE CHARACTERISTICS

Wash-free rice (WF rice) had the following characteristics; high moist ure content, high degree of brightness (high L-value) and also, low co ntents of protein, crude lipid and total free fatty acid. However, the re were slight differences in the total free fatty acid contents among WF rice samples. For the residues of processed WF rice, the contents of protein and crude lipid were high. These characteristics suggest th at the removal of the aleurone layer was more efficiently conducted by the treatment for wash-freeing than by the ordinary polishing treatme nt. WF rice packed in air underwent the following changes in a storage test. The high degree of brightness initially observed far WF rice we re apt to be kept during the storage. The beginning temperature of gel atinization was lower in WF rice compared to the ordinary milled rice for the same raw material. Further, the time-course increases in the m aximum viscosity and the final viscosity tended to be low. The increas e in the total free fatty acid content in WF rice compared to the ordi nary milled rice tended to be small. These tendency was marked for the stored rice under ambient temperature package in polyethylene film an d slight for PVDC coated-nylon film package. Storage al a low temperat ure (at 15 degrees C) resulted in small changes in rice qualities and so, the differences between WF rice and the ordinary milled rice were also small. Determined values by using ADAM and fat acidity determined by the conventional method were in close correlations. The relation b etween these two values could be expressed in the following equation: y = 2.4x - 0.15. The correlation coefficient was O.995 and thus, a sig nificant correlation was found between the two (P < 0.01). An eating t aste test was carried out after storage for 1 year, and significant di fferences between WF rice and the ordinary milled one were found in re spect of flavour (P < 0.05) and of stickiness (P < 0.01). These signif icances were assumed to be mostly due to the low content of free fatty acid content.