Fine flour from corn and the isolated starch were dextrinized in the presence of acid and irradiated with y‐rays. Starch irradiated with high doses of y‐rays was highly modified while fine flour was less affected. The irradiated starch was reduced with sodium borohydride and then hydrolysed. Erythritol and other compounds were identified in the hydrolysate. It was concluded that the C2‐C3 bonds in the intermediate glucose units are probably broken by irradiation. Such hypothesis was confirmed by periodate oxidation, hydrolysis with α‐amylase and ferricyanide number determination of the irradiated starch.

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while the DE increases are of the same magnitude. This we would explain by the jet cooking itself contributing with anon enzymatic DE increase caused by the mechanical shear in the jet cooker. ConclusionA comprehensive set ofnew data on the stability ofTermamyl has been presented. Amathematical expression describing the DE development during liquefaction, depending on actual operating parameters, has also been elaborated.Predictions of DE development based on this expression have been found to be in reasonally good agreement with later pilot plant results. The basis data and the formula may provide a useful tool in process optimizations in new and existing starch liquefaction units.

The field experiment was conducted to study the effect of various levels of chlormequat (CCC) and alar on the biochemical changes in tomato plants and fruits at different stages of growth. This experiment included spraying with chlormequat and alar separately in two equal doses (250, 500 and 1000 ppm CCC or alar 25 and 40 days after transplanting). The different levels of chlormequat decreased the accumulation of dry matter in tomato plants, but alar increased it. Chlorophyll a, b, total chlorophyll and carotenoids content of tomato plants increased by the application of CCC or alar. The highest increase of concentration of chlorophyll a, b and carotenoids in tomato plants were found by spraying with 500 ppm alar or CCC. The application of CCC and alar declined the percentage of carbohydrates and the highest decrease resulted by adding of 1000 ppm alar or CCC. Alar caused an increase in the percentage of total nitrogen at the different stages of growth. The concentration of P, K, Ca and Mg increased by the foliar spray of all treatments. Alar application at all used levels significantly increased the yield and also the weight of fruits. Highest plant productivity was obtained by using alar and CCC at 250 ppm, followed by 500 ppm. However, the highest concentration (1000 ppm) depressed the plant productivity. The concentration of juice, total soluble solids and vitamin C in tomato fruits increased at most of the levels added. But the percentage of total sugars and total acidity seemed to exert another trend. The highest concentration of N, P, K, Ca and Mg in fruits was obtained by foliar application of 500 ppm CCC or alar.

The rates of starch‐hydrolysis by different bacterial amylases were compared using the digital oscillator densimeter technique. Reaction rates of amylase determined by this method were evaluated using the standard method for amylase activity.