: This review of starch is concerned with its industrial uses, origins and structure. The current demand for starch is met by a restricted range of crops, the most important of which are potatoes, maize, wheat and tapioca. Improvements in the properties of starches for industrial uses can be achieved through chemical and physical modiÐcation of extracted starch and through the manipulation of starch biosynthesis in the plant itself. We examine starch structure and composition in relation to its use and exploitation by industry. The current understanding of physiological and biochemical mechanisms inÑuencing starch formation in higher plants is described. This information is set in the context of the need to know the physical/chemical speciÐcation for each individual starch and to understand the genetic control of these characteristics in order to identify target genes for manipulation.1998 SCI. ( J Sci Food Agric 77, 289È311 (1998)

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U S 1993. Enterobacteria were isolated from grass and silages and identified by the API 20E system. T h e effects of various ensiling treatments on their numbers and types were determined. T h e enterobacteria appear to follow a pattern of succession. Erwinia herbicola and Rahnella aquitilis dominated on fresh grass b u t after ensiling were rapidly superseded by Hajnia alvei, and finally Escherichia coli. Serratia fonticola may appear early on if the p H falls very rapidly.

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Starch accumulation is reduced when endosperms develop at elevated temperatures. Reduced starch deposition does not appear to be due to limiting assimilate levels during the grain filling period; on the contrary, endosperm sucrose may even be increased at the elevated temperature. Results indicate that elevated temperatures significantly reduce the activity of the sucrose cleavage enzyme UDPsucrose synthase (EC 2.4.1.13), found in the endosperm during grain development, and that these effects may be initiated by a relatively short period of thermal stress applied close to anthesis. It would appear that, when developing barley ears are exposed to elevated temperatures, there is an irreversible reduction in the capacity of the endosperm to convert sucrose to starch, caused by a decrease in the activity of at least one of the enzymes involved in this conversion pathway.