Effects of Thawing Conditions on Physical Properties of Frozen Tempe

Abstract

Tempe is soybean-based fermented food from Indonesia. In countries outside Indonesia, including in Japan, tempe is mostly purchased in a frozen form because of its short shelf life. Inappropriate thawing may result in lowering the food quality. The study aims to investigate the effect of thawing conditions such as water immersion thawing (WIT), hot steam thawing (HS), ultrasound-assisted thawing (UAT), and microwave thawing (MT) on frozen tempe. This study showed that WIT had the longest thawing time and lowest hardness value. Although HS had a short thawing time, it had a lower hardness value compared to fresh samples. Furthermore, MT had the highest color difference (ΔE) and decreased in hardness value compared to fresh samples. UAT at 150W is considered as optimal thawing conditions because it not only significantly shortened the thawing time by 32% but also showed the best retention in the original hardness and color properties of fresh tempe compared to other thawing conditions. Thawing time had a significant negative correlation with thawing loss at the 5% level, and thawing loss had a positive correlation with yellowness (b*) (p<0.01) and color difference (ΔE) (p<0.01) values.