Effect of High Temperature–High Humidity Treatment of Germinated Unkilned Barley on Malt Quality and Extract Characteristics
S. Tejinder1,2
1 Department of Food Science and Technology, Punjab Agricultural University, Ludhiana 141004, India.
2 Corresponding author. E-mail: tejinder108@yahoo.co.in
J. Inst. Brew. 113(2), 219–227, 2007 | VIEW ARTICLE
ABSTRACT
The effect of a high temperature–high humidity treatment (HTHHT) of germinated unkilned barley on malt quality and extract characteristics was studied. Two samples of six-row barley were steeped to 42% moisture and germinated, with and without gibberellic acid, at 15°C for 5 days. The germinated barley was placed in a high humidity (75–80%) atmosphere maintained at 45, 55, and 65°C, respectively. For each temperature, treatments were carried out for 30, 60 and 90 min, respectively. At 45°C for 30–60 min, the malts developed high diastatic power and proteolytic activity. The high values for cold water extract and reducing sugars in the extracts indicated extensive amylolysis of starch granules during HT-HHT of the germinated barley at 55–65°C. The worts were light in colour, with a pH of 5.3–5.8 and titratable acidity was in the range of 0.09–0.23%. A consistent increase in soluble nitrogen and Kolbach index was observed in the malts treated at 45–55°C for 30–90 min. Free α-amino nitrogen of the malts was in the desirable range of 120–150 mg L–1. Therefore, HT-HHT can be useful for improving malt modification and wort characteristics and to shorten the germination time for malts from poor quality barley.
Key words:
Extract analysis, germinated unkilned barley, high temperature–high humidity treatment, Kolbach index, malt.
Publication no. G-2007-0806-463 ©2007 The Institute & Guild of Brewing