Citrus Processing Varieties

Combined effect of high hydrostatic pressure and mild heat treatments on pectin methylesterase (PME) inactivation in comminuted orange

“…PME activity was determined using the method described by Kimball . The enzyme was extracted by homogenizing the comminuted sample with a 2 mol L −1 NaCl solution at a ratio of 2:1 (v/w) for 10 min, followed by centrifugation (model SL 16R centrifuge; Thermo Scientific, Pittsburgh, PA, USA) at 8330 × g for 20 min at 4 °C.…”

Effect of Maturity, Processing, and Storage on the Furanocoumarin Composition of Grapefruit and Grapefruit Juice

“…Spoiled fruit were not investigated as unsound fruit are culled during processing operations and converted with the peel residue into cattlefeed. While citrus fruit surfaces are covered with fungal and bacterial microflora in the field, during processing the fruit surfaces are washed and machinery is designed to minimize the amount of peel components expressed into juice as they negatively affect juice quality (Kesterson and Hendrickson 1957; Kimdall 1999). Thus differences in microflora composition with the season, maturity, and climate could be a reason for the variability in FC amounts seen in fruit peel (Widmer and others 2004; De Castro and others 2006), however, one would not expect changes in the juice so long as fruit utilized are sound and incorporation of peel components into juice is minimized.…”

“…Processing parameters do affect the composition of citrus juice (Kesterson and Hendrickson 1957; Kimball 1999) with more extreme pressing giving a higher juice yield from fruit, but also incorporating more peel components into the juice. Extraction pressure has an influence on polyphenol content in juice particularly naringin, narirutin, didymin, and phlorin (Cancalon 1999).…”

“…Differences in settings for fruit extraction to achieve higher juice yields can have a dramatic effect on the naringin content in grapefruit juice due to the much higher amounts of naringin present in peel components (Kesterson and Hendrickson 1957; Kimball 1999), and this is usually carefully monitored to prevent excessive bitterness in juice products. With the much higher amounts of DHB found in the peel (Widmer and others 2004; De Castro and others 2006), one would expect differences in processing to affect the amounts found in expressed juice.…”

Phenolic composition and total antioxidant capacity of South African frozen concentrated orange juice as affected by varietal, seasonal and regional differences

“…The lower TA could be due to the accumulation of carbohydrates and water in the fruit, which results in a decrease in the tartness or characteristic acidity because of a dilution effect as the fruit matures . In addition, when citrus fruit (especially ‘Navel’ oranges) are grown in warmer climates (where higher temperatures are observed), the respiration rate will be higher and the citric acid reserves will decrease as a result . This makes ‘Navel’ oranges less suited to warm environments.…”