Changes in the physical and chemical properties of the plasma membrane from hypodermal mesocarp tissue of netted muskmelon (Cucumis melo L. var. reticulatus Naud.) fruit were compared in relation to the permeability changes of the same tissue during fruit maturation and storage at 4 or 24C. As muskmelon fruit progress from immaturity to maturity, and with storage of mature fruit at 4 or 24C, increased permeability of the hypodermal-mesocarp tissue occurs coincident with an increase in the saturation index of the plasma membrane phospholipids. Buoyant density of the plasma membrane from hypodermal mesocarp tissue increased from 1.13 to 1.14 g·cm-3 during fruit maturation. Vanadate-sensitive ATPase (EC 3.6.1.35) activity was highest in mature fruit at harvest. After 10 days of storage, vanadate-sensitive ATPase activity was much lower in fruit kept at 24C than in those kept at 4C. The decrease in vanadate-sensitive ATPase activity in fruit stored at 24C was correlated with increased hypodermal-mesocarp membrane permeability. We suggest that biochemical changes affecting the lipid matrix of the plasma membrane influence fruit membrane permeability and possibly muskmelon storage life.

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STEIN, BROWNcesses and eluent volume should be an important factor influencing its displacement.Increasing eluent volume from 25 to 50 ml significantly increased thiamine recovery (mean recovery increased from 90 to 97.5%) and decreased the standard deviation from 2.15 to 1.53 (Table V). Hence, eluent volume is an important factor affecting both the quantity and reproducibility of thiamine recovery from Decalso.Elution to 50 ml requires more reagent and time than for 25 ml. However, the acid-KC1 eluent is not expensive so time is the more important consideration. It averaged 15.9 min longer (about 29% longer) per column to elute to 50 ml than to 25 ml (Table VI). However, the additional time is not cumulative when 6-12 columns are run a t once.Hence, for maximum precision and accuracy in the thiochrome method the important effects of eluent temperature and volume on thiamine recovery from Decalso must be recognized and controlled. Both factors could cause inaccuracy when sample extracts are purified on Decalso by hot elutions on unthermostated columns to 25-ml eluent volume. The nearly quantitative recovery of thiamine possible on unthermostated columns by hot elution to 50 ml suggests a standard curve may now be used in the thiochrome method instead of standards run for every set of determinations as is now generally recommended.

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Seasonal and storage characteristics of the juice from four red-fleshed grapefruit (citrus paradisi macf.) cultivars; Ruby Red, Henderson, Ray, and Star Ruby were determined and compared in a search for cultivars having juice with less tendency to fade as the fruit matures and on juice storage. Analyses of the single strength processed juice showed the cultivars to be similar except for lycopene and carotene values. Lycopene, the major pigment in pink and red grapefruit, declined 0.75-0.68 mg/lOOg, 0.36-0.25 mg/lOOg, 0.36-0.30 mg/lOOg and 0.14-0.08 mg/lOOg for Star Ruby, Henderson, Ray, and Ruby Red, respectively, as the season progressed. Storage of processed juice for 12 months revealed no major decrease in lycopene.