SUMMARY An unstable compound with an intense odor of “burnt pineapple” was isolated as a major component of a pineapple flavor concentrate. This compound was tentatively identified as 2,5‐dimethyl‐P‐hydroxy‐3(2H)‐furanone (I).

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SUMMARY Developing pineapple fruit were analyzed at weekly intervals, two lots in 1958 and four lots in 1963. Both spring and summer harvests were included. Soluble solids, sucrose, reducing sugars, titrable acids, pH, citric acid, and alcohol‐insoluble solids in the flesh show consistent patterns of change during fruit development. The soluble solids and pH of the shell tissues also relate to fruit development, but differ from those in the flesh tissues. By contrast, malic acid and ascorbic acid appear to vary in association with short‐term weather conditions, not with stage of fruit development. The trends in carbohydrate and acid constituents of pineapple fruit suggest several discrete physiological stages: prematuration; maturation, beginning about seven weeks before normal ripeness; ripening, beginning two to three weeks before the half‐yellow stage of ripeness; and senescence.

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VIuch confusion appears in the literature concerning the effects of fast and slow freezing on the quality of vegetables. In this study, five different rates of freezing were employed, ranging from very rapid, by means of liquid air, to very slow, in an insulated box. Peas and snap beans were blanched, frozen, and stored at -6°F. for six months. Analyses were made for ascorbic acid, carotene, and thiamine.Riboflavin was run on peas only. Analyses were madfe on raw, blanched, and frozen samples, and again after six-month storage and after cooking. Significant differences in vitamin content could not be detected among the samples from the rates of freezing studied. Significant differences in taste and texture were not observed, with the exception of the texture of those frozen in liquid air. These were somewhat softer, probably because of cracking that took place during freezing. Photomicrographs show that the slower the rate of freezing, the larger the ice crystals; but in the corresponding thawed samples, these differences disappeared, and damage was not apparent.A NUMBER of articles have been published relative to the effect of freezing rate on the quality of quick-frozen vegetables. Woodroof {12, IS) indicated that slow freezing of nonstarchy vegetables resulted in flabbiness; in the case of starchy vegetables, such as peas and shelled beans, less change was noted, apparently because of the support lent to the cell walls by the starch grains.Joslyn and Marsh (4) "do not find that there is a direct relation between loss in weight of treated fruits and vegetables and change in texture as judged by the degree of retention of original shape, turgidity, and crispiness" as reported by Woodroof. Table 14 of their article shows that steam-blanched asparagus, frozen in still air at 0°F., lost 25.2 % in weight when thawed one year later. The same lot of asparagus, steam-blanched but frozen in dry ice at -110°F ., showed a loss of 14.4% when thawed a year later. The figures for corresponding treatments of peas were 6,6 and 0.6%, respectively, and for string beans, 13.8 and 6.8%, respectively. They, further stated: "It has been our experience that with the possible exception of asparagus, increasing the rate of freezing by using solid carbon dioxide did not appreciably improve the texture of fruits and vegetables examined." Diehl and Berry {l) reported: " ...

In 1922 Newton and Gortner (1) put forward the hypothesis that at least a portion of the water associated with the hydrophilic colloids in plant tissues was in a "bound" form, in which form it exhibited physicochemical properties which would serve to differentiate it from the "free" water of the vacuolar sap. It was suggested that bound water might be unavailable for the solution of sucrose and accordingly a method for the estimation of such bound water was proposed which consisted essentially in first determining the freezing point of the solution which contained the hydrophilic colloid and denoting this value as A. An amount of the sol was then taken which contained exactly 10 gin. of total water. To this portion there was added 0.01 mole of sucrose and a second depression of the freezing point, designated Aa, was determined. If all of the 10 gin. of water were free to dissolve sucrose ha should differ from A by the freezing point depression of a molar solution of sucrose which according to Satchard (2) should be 2.085 °, corresponding to a gram molecule of sucrose-hexahydrate dissolved in 892 gm. of water.The formula which Newton and Gortner proposed Aa --(Zx -b Kin) percentage of bound water ---X 89.2 (1) Aa --A was tested by them on aqueous solutions of gum acacia and on certain plant saps and appreciable amounts of bound water were apparently demonstrated to be present. This method has been extensively used by numerous plant physiologists-especially Newton and his coworkers (3-6)--and has

SUMMARY Pigments in the shell and flesh tissues of developing pineapple fruit were analyzed at weekly intervals on four different lots of fruit ripening in the spring and in the summer of 1963. Chlorophyll in the shell showed little change until final ripening began. It then disappeared during the final two weeks of development. Anthocyanin and chalcone compounds in the shell fell off steadily throughout fruit development. The carotenoid pigments in the shell showed a small downward trend during development, followed by a small rise during senescence of the fruit, after the chlorophyll had disappeared. In the flesh, however, the carotenoids showed quite marked changes. These pigments fell until about seven weeks before ripeness, then rose markedly during the final two‐week ripening period. The trends in plant pigments are consistent with suggestions from earlier studies on nitrogenous, carbohydrate, and acid constituents of the pineapple during development, indicating that there are several discrete physiological stages for the fruit.

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