Freezing and Thawing Characteristics of Some Selected Nigerian Soups

Freezing and thawing characteristics of some Nigerian soups (Ila, Ewedu, Ogbono and Kuka) were investigated. The soups were prepared using standard recipe and packaged in plastic and aluminum containers, frozen at −20C and thawed with microwave oven water (2.45 GHz), hot water (100C) and at ambient condition (30 ± 2C). Freezing and thawing durations, rates, losses and points of the soups were determined using standard methods. Data were analysed using SPSS at P = 0.05. Freezing duration, rate, loss and points were 70.0–145.0 min, 0.4–0.7C/min, 1.75–3.79%, and −1.8 to −2.4C respectively. Thawing duration, rate, loss and points were, 1.8–53.0 min, 0.4–10.9C/min, 0.1–2.4% and −1.7 to −2.3C respectively. Soups packaged in aluminium containers frozen faster than in plastic containers. Microwave-thawed soups in plastics showed the best thawing characteristics which include high thawing rate, short thawing time and low thawing loss. Practical Applications Evidence of richness of Nigerian soups has been reported by many researchers. In order to maintain the quality of frozen selected Nigerian soups and to reduce the cost of their preservation, the freezing and thawing characteristics of the selected soups should be established. Freezing is an effective preservation technique that maintains the keeping quality of both processed and freshly harvested products. This method of preservation is considerably complex and quality of frozen food depends not only on the temperature, the freezing rate, freezing time and maintenance of the cooling chain, but also on the thawing conditions. Freezing and thawing characteristics of the selected Nigerian soups established are essential in the calculation of refrigeration requirements and the design of equipments for Nigerian soups preservation. Also, the data obtained can be applied to cold chain marketing of the soups to guide against sensory and nutritional losses during cold storage.