Seasonal Changes Occurring in the Pectinesterase Activity and Pectic Constituents of the Component Parts of Citrus Fruits II. Pineapple Oranges^a

Abstract

SUMMARY Pectinesterase activity, 3 pectic fractions, and other characteristics were determined periodically on 5 component parts of Pineapple oranges during a 9.month maturation cycle for 2 seasons. Generally, PE activity was greatest in the peel, membrane, and juice sacs in March, April, and May, when the Brix/acid ratio was highest. However, the activity varied in similar components for like months during the 2 seasons. The order of component parts for PE in most cases, from highest to lowest activity, was juice sacs, membrane, peel, seeds, and juice. Total PE in the average whole orange attained maximum activity in March and April. Over 52% of the activity present was found in the juice sacs, which represented about 22.5% of the whole fruit. Water‐soluble pectin increased slightly in the peel and membrane, remained somewhat irregular in the juice sacs, and decreased to a constant level in the seeds throughout the growing season. Ammonium‐oxalate‐soluble pectin in the peel decreased slightly, and in the other components was either irregular or increased slightly, during maturation. Quantity of protopectin was greatest in the membrane and generally decreased toward the end of the sampling period in the various components. Total pectin and weight of the average whole orange was greater in the 1961–62 season than in the preceding season.

Pectic Enzymes and Development of the Pear (Pyrus communis)

“…The results also would correlate well with the observation of Gee et al (1959) on the percent esterification of pectin ; i.e., PE activity was greatest in the immature pear where the percent esterification of pectin is lowest, whereas PE activity was minimal in the mature fruit where the percent esterification is greatest. These results differ from those obtained with oranges (Rouse et al, 1962(Rouse et al, , 1964 and bananas (Hultin and Levine, 1965). In oranges PE activity on a weight basis either remained constant or increased during maturation of the fruit.…”

Effects of freezing conditions on quality changes in blueberries

“…The different pectins were extracted using the method described by Rouse et al . and Majumder and Mazumdar with slight modifications.…”

“…The pectin contents were measured using the carbazole spectrophotometric method at an absorbance wavelength of 530 nm. The galacturonic acid curve for the standard sample was used to calculate the pectin content (g kg −1 ).…”

“…The different pectins were extracted using the method described by Rouse et al 18 and Majumder and Mazumdar 19 with slight modifications. A 95% ethanol solution was used to remove sugar and other material from the blueberries.…”

History, Global Distribution, and Nutritional Importance of Citrus Fruits

“…The main fractions of citrus polysaccharides are pectic substances, hemicelluloses, cellulose, and lignin (Ting 1980; Table 5). Individual hydrolysis of the pectin, hemicelluloses, and cellulose revealed that certain monosaccharides, such as arabinose and galactose, were discovered in all fractions, whereas free xylose primarily existed in the hemicellulose fraction, and galacturonic acid and glucose dominated the pectin and cellulose fractions (Ting and Deszyck 1961; Rouse and others 1962, 1964). Previously reported results, based on the assumption that each hydrolyzed product is derived from a homogeneous polysaccharide, suggested that orange and grapefruit peels consist of 7% to 10% araban, 5% to 6% galactan, 2.5% xylan, 15% to 28% cellulose glucosan, and 23% polygalacturonic acids, accounting for approximately 53% to 70% of the ethanol‐insoluble solids in the peel (Ting and Deszyck 1961).…”