Mechanical properties of maize kernel horny endosperm, floury endosperm and germ

Abstract

ABSTRACT Mechanical damage of maize kernel caused by external forces during processing is closely related to its internal mechanical properties. In this research, three main tissues’ (horny endosperm, floury endosperm and germ) mechanical properties of three maize varieties (Jinyu818, Zhengdan958 and Dafeng30) and five stages of moisture contents (11.78–34.73% w.b.) were evaluated using puncture test. Results showed that there was no (p > .05) or weak significant (0.01 < p < .05) difference between varieties, while significant moisture and tissue material effects were observed. For rupture force (Frp ), ultimate strength (σb ), toughness (Trp ), initial firmness (Finf ), average firmness (Favf ), modulus of elastic (E), apparent modulus of elastic (AME), bioyeiled force (Fby ), bioyeiled strength (σs ) and penetration force (Fp ), outer layer tissue (horny endosperm) of maize kernel at lower stage of moisture contents were higher than those of inner layer tissues (floury endosperm and germ) at higher moisture contents. While for bioyeiled deformation (Dby ) and rupture deformation (Drp ) values, results showed that inner layer tissues at with higher moisture content were the highest. Pearson’s correlation analysis showed that most of the parameters had a significant correlation (p < .01, r > 0.80) with each other. This study can be considered as a contribution towards further studying and minimizing the mechanical damage of the maize kernel when applying external force during and post harvesting.