Popping Mechanism of Popcorn Grain

Abstract

The popping mechanism of popcorn grain (Zea mays everta), when heated at 200°C or at 220°C under atomospheric conditions, was studied in terms of; i) comparison of starch granule isolated from several kinds of corn grains, ii) characteristics of the structure of grains and iii) scanning electron microscopic observation of popping grains during heating. (1) Property of the starch granule isolated from popcorn did not differ from that of dent corn so much in gelatinization temperature and pasting characteristics, although its amylose content was slightly higher than that of dent corn (by 3% or so). The differences in the structure of grains were rather prominent to characterize the popcorn. (2) From the scanning electron microscopic observation of popcorn grain during popping, the starch in hard endosperm was gelatinized higher than 160°C and make a honeycomb structure by the expansion of vaporized air. In the popped products thin film-like membrane was made by the ge1atinized, sintered starch. (3) It was found that the starch granule gelatinized at the range of 130-170°C in the popping corn grains and the degree of gelatinization was about65-75%, The nature of hull, being able to tolerate the inner vapor pressure enough during heating was essentially important for the preparation of popcorn.