Stabilization of Carrot Juice by Dilute Acid Treatment

Abstract

SUMMARY– A problem arises if juice extracted from raw carrots is heated to about 180° before or during conventional canning practices. An unsightly, unappetizing coagulum forms and the color of the juice precipitates with the coagulum. The coagulum is not as evident if the carrots are heated 5 min in water prior to juice extraction, but the juice loses some of its bright‐orange color. The canned juice extracted from carrots heated 5 min in a .05 N acetic acid solution does not coagulate and the amount of juice which can be extracted from the carrots is 3.3% greater than that from carrots heated 5 min in water. The centrifuged juice from acid‐treated carrots had a brighter orange color than juice from the water‐treated carrots. The color notation was Rd, 23.7, a, 30.4 and b, 34.8 for juice from acid‐treated carrots compared with a notation of Rd, 19.2, a, 24.4 and b, 31.4 for the juice from water‐treated carrots. The canned juice extracted from raw carrots had less pectic substances and starch and about the same amount of protein as the canned juice from the carrots heated in water or .05 N acetic acid, but the canned juice from raw carrots coagulated. The juice from carrots heated in acid does not form a coagulum and maintains its orange color, probably because of the action of the heat and acid on the protoplasmic liquid of the cell before or immediately after the cell is ruptured.

Adjustment of milling, mash electroporation and pressing for the development of a PEF assisted juice production in industrial scale

“…This may be partly related to manipulation of the juice composition by water transfer from the belt due to the belt cleaning system. TDS values depend very much of the carrot variety and processing technology but values obtained in the present study were in accordance with values reported by Stephens et al (1971) for juice from raw (7.0-7.5°Brix) and heated (7.6-8.2°Brix) carrot mash. Praporscic et al (2007) studied the changes of TDS content for carrot juice when applying PEF treatment during pressing.…”

Carrot Juice Color, Carotenoids, and Nonstarchy Polysaccharides as Affected by Processing Conditions

“…Bates and Koburger (1974) reported that juice from carrots blanched at 1OOT for 5 min were pH 6.2, similar to our results. The decrease in pH among canned canot juices of three treatments was probably due to heat decomposition of peck substances to pectic acid and the absorption of acetic acid by carrots which decreases juice products (Stephens et al, 1971). The small decrease in pH was not enough to protect against microbial growth.…”

“…Canned carrot juice is a low-acid food requiring high-temperature heat processes to kill bacterial spores. Although high temperature could cause a coagulum to form in the juice, Stephens et al (1971Stephens et al ( , 1976 found that juice extracted from carrots blanched in 0.05N acetic acid did not form a coagulum and maintained good color and flavor. High temperatures, especially retorting temperatures could destroy carotenoids in carrots (Khan et al, 1975;Kim and Gerber, 1988).…”

Sedimentation behaviour and turbidity of carrot juices in relation to the characteristics of their cloud particles

“…CJ samples (8 • Brix) and their turbid sera were diluted with water (1:4 v/v). A 5 ml aliquot of diluted sample was placed on top of a sucrose gradient consisting of six layers of sucrose solutions of 5,15,25,35,45 and 55 • Brix with corresponding densities of 1.0196, 1.0610, 1.1056, 1.1534, 1.2047 and 1.2597 g ml −1 , respectively. Coarse particle fractions were adjusted to original juice weight with demineralised water and redispersed by vigorous shaking prior to isopycnic density gradient centrifugation at 60 600 × g for 2 h. During centrifugation the temperature increased from 0 • C to approximately 20 • C. Layers containing cloud particles were fractionated and the sugar contents of the fractions were determined refractometrically.…”