ACTA ALIMENTARIA VOL. 8 (A QUARTERLY OF THE COMMITTEE ON FOOD SCIENCE OF THE HUNGARIAN ACADEMY OF SCIENCES, 1979)

1979 / 1. sz. - KOLOSTORI, M.: Flour quality and proteolysis

2 KOLOSTORI: FLOUR QUALITY AND PROTEOLYSIS "Enzyme pH 5" degrades haemoglobin and casein at about pH 4-5. The reaction is not inhibited by diisopropyl fluorophosphate (DFP) and iodine acetate. "Enzyme pH 7" breaks down trypsin substrate N-alfa-benzoyl-DL-arginine-4-nitroanilid (DL-BAPA) at a pH optimum of 7.5. It does not degrade N-succinyl-L-phenylalanine-4-nitroanilid, the substrate of chymotrypsin. Its activity may be inhibited with DPP and this points to the presence of serine protease. Its similarity to trypsin appears not only in its substrate specificity but in its reaction to inhibitors as well. This enzyme or group of enzymes may be inhibited by l-chloro-3-tozylamino-7-amino-heptanone-(2), which is a specific trypsin inhibitor. On the other hand, the chymotrypsin inhibitor l-chloro-3-tozylamino-4-phenyl-butanone-(2) does not affect activity. According to BELITZ and LYN EN (1974) further investigations are neces­sary to show whether "enzyme pH 7" is identical with the gluten-softening alfa-protease described by HANFORD (1967). BREYER and HERTEL (1973) studied protease activity in wheat and rye flour using BAPA. The advantage of this method against those applying natural substrates lies in the use of a synthetic substrate of constant and well-defined composition. This results in a known hydrolysis product the con­centration of which is measurable by colorimetrv. The protease activity of a great number of wheat varieties was deter­mined on bacto-liaemoglobin and DL-BAPA substrates in order to be able to compare the two methods and their effect on the physical characteristics of the dough and on the volume of the end product. 1. Materials and methods The flour of about 0.5% ash content, used in the experiments was pre­pared on a laboratory mill. The physical characteristics of the dough were studied with a Farino­graph, an Extensogmph and a Maturograph (POMERANZ, 1971). The behaviour of the dough during kneading was characterized by a cpialitv index (Q) determined on the basis of the farinogram (Hungarian Standard 6369/6-73). For the Extensograph and Maturograph measurements the dough was prepared in the Farinograph (kneaded in a 300 g bronze trough for 3 min). When prepared for the Extensograph, 2% salt was added to the dough. The dough was allowed to stand for 45 min, then it was stretched in the Extenso­graph and the resistance to extension was measured in Brabender units (BU). For studies on the Maturograph 2% salt, 4% yeast and 0.5% sugar were added to the dough. After kneading the dough was allowed to stand for Ada Alimevlaria 8,1979

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