Quality of Acid-Preserved Edamame Soybean at Immature and Mature Stages

David Moseley,Pengyin Chen,Liliana Florez-Palacios,Leandro Mozzoni,Moldir Orazaly

doi:10.3389/fsufs.2020.569625

Abstract

Edamame is a food-grade soybean that is harvested at the green-immature stage (R6) and sold fresh or frozen for consumption after steaming or boiling. Limited studies have been conducted on high-temperature sterilization of edamame in cans and on acid preservation of edamame. The objectives of this study were to evaluate the color retention and texture of edamame when pasteurized in acidic brine as compared to boiling, to assess the effect of sucrose and turmeric addition on acid-treated edamame, and to characterize varietal differences when edamame lines were pasteurized in an acidic brine at either R6 or R8 stage. All studies were conducted using industry-standard processing conditions for acid-preservation of food in glass containers. The results of this research indicated that acid processing caused losses in intensity of green color and hue, but much smaller than those reported when heat-processing edamame in cans. We also observed a small and borderline significant increase in texture (p=0.0790) in acid-preserved samples. In addition, we found that green color is positively affected by the addition of turmeric to the brine, but not of sucrose. Finally, the varieties R07-589 (red-brown seed coat) and R09-345 (black seed coat) acid-processed at R8 had color and texture similar to canned in-kind substitute products. In conclusion, acid-preservation, and addition of turmeric to immature edamame, helped maintain an acceptable quality of the processed products.

Highlights

Edamame is a food-grade soybean (Glycine max (L.) Merrill) that is high in protein and phytochemicals and low in saturated fats, making it a good food product for addition to soups and salads, or as healthy snack alternative to chips and candy (Masuda, 1991; Rayaprolu et al, 2015)
Mozzoni et al (2009a) established a protocol to blanch edamame before sterilization to deactivate lipoxygenase activity; and developed a base brine consisting of NaCl and CaCl2
Czaikoski et al (2013) adapted the protocol set by Mozzoni et al (2009a) by pasteurizing in an acidic brine and evaluating levels of sucrose to retain green color

Summary

Introduction

Edamame is a food-grade soybean (Glycine max (L.) Merrill) that is high in protein and phytochemicals and low in saturated fats, making it a good food product for addition to soups and salads, or as healthy snack alternative to chips and candy (Masuda, 1991; Rayaprolu et al, 2015). Edamame can be harvested when the seed is mature and dry at the R8 reproductive stage. While the seed color at R6 is green, it will either stay green or turn yellow, black, red-brown, or brown at the R7 stage, depending on the genetics of seed-coat and cotyledon color for the particular variety (Kiuchi et al, 1987). While all commodity-soybean have yellow seed coat, some of the edamame lines are selected to have green cotyledons to facilitate harvest, for these lines. The pigments responsible for the various seed coat colors at the R8 reproductive stage can have health benefits, such as inflammation-preventing anthocyanins and procyanidins in the black, red-brown and brown seed coats (Takahata et al, 2001; Kim et al, 2006; Nizamutdinova et al, 2009)

Objectives

Methods

Conclusion