Ascorbic Acid Content of Pineapples as Correlated With Environmental Factors and Plant Composition

Abstract

The ascorbic acid content of plants may vary widely depending upon the conditions under which the plants are grown, Maynard and Beeson (1944). I n recent work with tomatoes relatively great variations in ascorbic acid were found correlated with the season and location at which the plants were grown, while little influence of the supply to the plant of macronutrient and micronutrient elements was apparent [ Hamner, Lyon, and Kamner (1942) and Lyon, Beeson, and Ellis (1943)l. The work of many investigators [Hamner and Parks (1944) ; Reder, Ascham and Eheart (1943) ; Reid (1941, 1942) ; and Murphy (1942) ] with numerous plants has indicated that such climatic environmental factors as air temperature, light intensity, length of day, and rainfall have an influence on ascorbic acid values. On the other hand, there is much disagreement among investigators as to whether o r not soil conditions and fertilizer practices exert any effect.A study of the ascorbic acid content of pineapple fruit in Hawaii was thought to be profitable, especially since variations in the vitamin could be followed in conjunction with variations in climate and plant composition. Only one variety of pineapple is grown and all plants are vegetatively propagated so that genetic differences between plants are not of concern. Climatic differences from one location to another a few miles away are relatively great. Plants are grown under conditions of temperature that differ materially at elevations approximating sea level to others over 2,000 feet. Light intensities vary from 2,000 to 8,000 foot candles, depending upon season and location. Differences in rainfall may be very great. Fairly complete records of these climatic variables are kept for each field location. In addition, careful records of fertilizer practices are available. Studies on the chemical composition of the plants and the fruit are extensive. With all of these data available it was thought that variations in ascorbic acid might be correlated with some particular variable of climate or fertilizer practice, or that a correlation between the vitamin content and some other plant constituent might become apparent. EXPERIMENTAL PROCEDUREThe ripe fruits from the experimental plots were harvested and processed to form juice in a commercial cannery. The samples of canned juice were shipped to the United States Nutrition Laboratory a t Ithaca, New York, and stored at 5.SoC.( 42OF.). The vitamin analyses were conducted as soon as possible thereafter.Hawaiian Pineapple Company, Honolulu, Hawaii. 535

Ascorbic Acid and Dry Matter Accumulation in Turnip and Broccoli Leaf Discs After Infiltration With Inorganic Salts, Organic Acids, and Some Enzyme Inhibitors

“…A similar situation has been observed for ascorbic acid in the leaves of pineapple plants (21). Furthermore, a close correlation was observed between the total organic acid and ascorbic acid contents of pineapples by HAMNER and NIGHTINGALE (7), but such a correlation does not apply to the diurnal fluctuation in organic acid content of the leaves of the same plant (22).…”

Pineapple and papaya

“…Ascorbic acid content of ripe pineapple fruit varies from 40 to 1100 fLM total juice and does not contribute substantially to titratable acidity. There is, however, a positive correlation (r = 0.956) between ascorbic acid and total acidity (Hamner and Nightingale, 1946). Its level in the fruit varies positively with the amount of solar radiation received by the fruit while still attached to the plant .…”

Symptom Development of Chilling Injury in Pineapple Fruit

“…Ascorbic acid levels have been associated with the degree of expression of symptoms of internal browning caused by chilling (10,14,23,27,30). The levels of ascorbic acid in pineapple vary widely with environmental factors (7,25), fertilizers (25), and postharvest treatments such as waxing (19). As with apples (16) and banana (12), ascorbic acid in pineapple may decrease the oxidation of phenols, until the levels of ascorbic acid in the chilling injured tissue is reduced, then polyphenol oxidase activity would increase and browning would occur.…”

“…Ascorbic acid serves both as an exzyme inhibitor and as a reducer of quinone (15). There is an identical gradient of ascorbic acid to titratable acidity within the fruit (7,9,11) with highest levels in the periphery and the top of the fruit. This gradient could, in part, explain the occurrence of chilling injury symptoms initially around the core, although this tissue might also be more susceptible than surrounding tissue to chilling injury.…”