CHARACTERISTICS OF SOYMILK AND TOFU OF FIVE VARIETIES OF SOYBEANS AS AFFECTED BY ON-SITE STORAGE

Abstract

Five soybean cultivars were harvested and stored on farm storehouses in the North Dakota-Minnesota region for up to 1 year. Sampling interval was 2 months. Soymilk was prepared with a fixed water-to-bean ratio. Soft tofu was made following a small-scale procedure. Tofu yield, color and textural properties were measured. Tofu smoothness and overall score were assessed by a sensory panel. Results showed no significant changes in tofu yield, textural properties and sensory scores throughout 1 year of storage. Tofu brightness (L*) and yellowness (b*) decreased, and tofu redness (a*) increased over the storage time, although changes were not always statistically significant (P < 0.05). Soymilk yield and total solids content varied in small ranges over the storage time. Our results indicate that storage of soybeans at ambient temperatures in this geographical region is suitable for preserving the freshness of soybeans stored on the farm facilities over a 1-year period. PRACTICAL APPLICATIONS Soybeans are subject to storage and transportation before processing. Most reported soybean storage studies have been carried out in the laboratory model systems, in which specific temperature and humidity were controlled, but aeration was limited. In practice, soybeans are subject to storage, in which the changes are from morning to night and from day to day. In this study, soybeans were stored in farm storage warehouses throughout the study period. The results provide new information on how on-site storage in Fargo area affects soymilk and tofu processing.