Nutritional and physicochemical characteristics of purple sweet corn juice before and after boiling.

Xuanjun Feng,Jie Xu,Fengkai Wu,Xuemei Zhang,Qingjun Wang,Wei Guo,Zhengqiao Liao,Jingwei Li,Erliang Hu,Liteng Pan,Yanli Lu,Xianqiu Wang,Leonidas Matsakas

doi:10.1371/journal.pone.0233094

Abstract

Sweet corn juice is becoming increasingly popular in China. In order to provide valuable health-related information to consumers, the nutritional and physicochemical characteristics of raw and boiled purple sweet corn juices were herein investigated. Sugars, antinutrients, total free phenols, anthocyanins, and antioxidant activity were analyzed by conventional chemical methods. The viscosity and stability of juices were determined by Ubbelohde viscosity meter and centrifugation, respectively. Boiling process could elevate viscosity, stability and sugar content, and reduce antinutrients, total free phenols, anthocyanins, and antioxidant activity in corn juice. In addition, short time boiling efficiently reduced the degradation of anthocyanins during subsequent refrigeration. The content of amino acids, vitamin B1/B2 and E were detected by High Performance Liquid Chromatography. Gas Chromatography Mass Spectrometry was used for the analysis of fatty acids and aroma compounds. Several aroma compounds not previously reported in corn were identified, including 1-heptanol, 2-methyl-2-butenal, (Z)-3-nonen-1-ol, 3-ethyl-2-methyl-1,3-hexadiene, and 2,4-bis(1,1-dimethylethyl)phenol. Interestingly, the boiling process had no apparent effect on the amino acids profile, but it caused a 45.8% loss of fatty acids in the juice by promoting the retention of fatty acids in the corn residue. These results provide detailed information that could be used for increasing consumers' knowledge of sweet corn juice, further development of sweet corn juice by food producers, and maize breeding programs.

Highlights

Sweet corns differ from normal field corns in the mutation of starch synthesis genes, e.g., Sugary (Su), Shrunken (Sh), and Brittle (Bt), which result in a higher accumulation of sugar and water-soluble polysaccharides at the milk stage than in normal field corns, and provide the sweet taste and creamy texture of sweet corns [1]
The amino acid composition and total soluble sugar contents of the raw and boiled sweet corn juices are presented in Table 1 and Fig 1, respectively
This is true for the boiling process because free amino acids and soluble sugars will leach into the surrounding water [13,17]

Summary

Introduction

Sweet corns differ from normal field corns in the mutation of starch synthesis genes, e.g., Sugary (Su), Shrunken (Sh), and Brittle (Bt), which result in a higher accumulation of sugar and water-soluble polysaccharides at the milk stage than in normal field corns, and provide the sweet taste and creamy texture of sweet corns [1].

Methods

Results

Conclusion