Polysaccharide Composition of Leaves
PLUM leaves (Prunus domestica) contain sufficient amounts of starch, cellulose, hemicellulose, and pectic substances to recommend them for studies of the biosynthesis and possible inter-relationships of these leaf polysaccharides and their monosaccharide precursors1. Experiments involving photosynthesis by plum leaves in carbon dioxide labelled with carbon-14 and subsequent fractionation of the leaf polysaccharides revealed marked differences, both in the extent to which carbon-14 was incorporated into the different monosaccharides of each fraction, and also in the specific activities of each monosaccharide from different fractions2,3. Further investigations could be facilitated by using leaves relatively richer than plum leaves in any one polysaccharide constituent. There is little information on this point, consequently a diversity of leaves has been examined for polysaccharides (Table 1).
Influence of temperature and growth stage on the diurnal fluctuation in the non‐structural carbohydrate content of kikuyu (Pennisetum clandestinum Hochst)
The non‐structural carbohydrates of kikuyu (Pennisetum clandestinum Hochst) seem to consist mainly of sucrose. Total non‐structural carbohydrate content increased rapidly during the morning and reached maximum concentration in the afternoon. After sunset, the concentration decreased rapidly, reaching a minimum level by midnight. Low temperatures resulted in a significantly higher non‐structural carbohydrate content in all plant fractions than at warmer growth temperatures. Non‐structural carbohydrate concentrations were higher in stem tissue than in leaf material and the values were higher in 3‐week than in 6‐week regrowth.
Synergistic Effect of High Temperature and High pH on the Destruction of Salmonella enteritidis and Escherichia co1i O157:H7.
This study was undertaken to determine if high temperature and high pH interact synergistically to enhance the rate of destruction of two important gram-negative foodborne pathogens, Escherichia coli O157:H7 and Salmonella enteritidis . The rates of destruction in NaHCO3-NaOH buffers at pH 7.0, 10.0, and 11.0 were determined at 35, 40, 45, 50, 55, 60, and 65°C. Use of an improved heating protocol eliminated a "tailing effect" at longer exposure times. The present study demonstrated that the combination of high pH and high temperature resulted in a highly significant synergistic interaction (P > F = 0.0001), which caused rapid death of both E. coli O157:H7 and S. enteritidis . This "alka-therm" technology might be used commercially to destroy gram-negative foodborne pathogens on various raw agricultural commodities.