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Abstract
Vegetable soybeans [Glycine max (L.) Merrill] are a green stage of soybeans, which have become increasingly popular among health-conscious Americans as an alternative low-fat and heart-healthy food. Vegetable soybeans (VSB) are also an excellent source of protein and fiber. However, the vast majority of the VSB consumed are imported, as they are not extensively grown and processed in the United States. The situation results in short supply and limited processing information.
The purpose of this study was to investigate the effects of water blanching (at 86, 92, 98 °C for 1m30s, 2m, 2m30s) and steam blanching (at 86, 92, 98 °C for 1m30s, 2m, 2m30s, 2m50s) on color, texture and sodium chloride content of frozen VSB during six-month storage time. It was hypothesized in this study that decreasing in blanching time and temperature from the conventional commercial process (98 °C for 2m30s - water blanching and 98 °C for 2m50s - steam blanching) would not affect the quality attributes of frozen VSB.
The results showed that blanching at temperatures lower than 98 °C for both methods did not completely inactive the peroxidase in VSB, which may cause quality losses during storage. Water blanching at shorter time than the control (2m30s) in commercial processing experiment did not effectively tenderize the texture of VSB. On the other hand, blanching time of all experiments can be reduced to 1m30s with comparable quality to the conventional processes.
Blanching apparently affected quality of VSB while freezing and frozen storage had no significant effects on the final product. Optimal processing results in the improvement of production efficiency, increasing production yield and profits. Knowledge from this study is anticipated to be, more or less, supportive and informative for VSB producers in the United States and everyone who interested in this valuable commodity, vegetable soybeans.
