(427) Seed Germination after Steeping in Saturated Lime Solutions

Abstract

A lime solution is an efficient starch gelatinization agent during the traditional process of nixtamalization of corn for tortilla production. Although the saturated Ca(OH)2 solution is usually heated to speed the process, similar physical-chemical changes occur to corn steeped at room temperature. In addition, the steeped grains are capable of rapid germination. In this study we explored whether, in barley grains subjected to the same steeping conditions, there would be an acceleration of biochemical changes for the production of malt. Barley grains cv. Esmeralda six-row were steeped in saturated solutions of lime from 0% to 2% (w/w) at 18 to 23 °C for up to 72 hours. After treatment, the grains were washed with water and placed in a germination cabinet at 20 ± 2 °C and 90% RH for up to 96 hours to germinate. Activity of α-amylase (U/mg protein), sprout length (cm), seed viability (tetrazolium test), and respiration rates were determined. Scanning electron micrographs were prepared. There was a very rapid uptake of lime solution by the barley grains during the first 30 hours of treatment. The barley grains were 98% viable after all periods of steeping. Grains steeped 24 hours and germinated 70 hours had the highest activity of α-amylase, longest sprout length and highest percentage of germination. Under SEM, chemical gelatinization of starch grains was observed in barley sections after different steeping treatments, and starch breakdown was observed in grains during germination. No fungal growth was observed during germination after the steeping treatments. These results demonstrate that steeping in lime solutions could shorten the period required for barley germination and similar conditions may be useful for germination of other cereal and vegetable seeds.