Degradation of pectic substances in carrots by heat treatment

Plat, D.; Ben-Shalom, N.; Levi, A.; Reid, David; Goldschmidt, Eliezer E.

doi:10.1021/jf00080a030

Cited by 41 publications

(27 citation statements)

References 8 publications

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“…This complements the Ðndings of Massiot et al (1992) who observed an increase of WS pectin extracted from carrot cubes heated in boiling water. It is interesting to note that after heat treatment at 100¡C and 800 g kg~1 moisture, the ratios of neutral sugars to uronic acid in the WS polymers increased, indicating that more highly branched pectic polysaccharides have been solubilised Plat et al (1988Plat et al ( , 1991 pertain to the water solubilisation of pectin in situ after heating, the present study shows a similar e †ect when CWM was puriÐed from carrot tissue and then heated. It can be concluded that glucose originated from polysaccharides other than starch as shown previously by 1 M hydrolysis.…”

Section: W Ater Solubilitysupporting

confidence: 68%

The thermomechanical properties of carrot cell wall material

Georget

Smith

et al. 1998

J. Sci. Food Agric.

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Section: W Ater Solubilitysupporting

confidence: 68%

The thermomechanical properties of carrot cell wall material

Georget

Smith

et al. 1998

J. Sci. Food Agric.

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“…First, p-elimination has not been demonstrated to occur during heat-softening of intact plant tissues. Most recently, Platt et al (1988) were unable to find evidence for p-elimination in blanched carrot tissue. Also, differences in ionic strength, buffer composition, and temperature between this experiment and the recent work of Sajjaanantakul et al (1989) on the P-elimination reaction were great.…”

Section: Discussionmentioning

confidence: 99%

pH Effect on Calcium Inhibition of Softening of Cucumber Mesocarp Tissue

McFeeters

Fleming

1991

Journal of Food Science

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The first-order rate of softening of cucumber tissue containing 1SM NaCl with and without 20 mM added calcium ion was determined from pH 2.5 to 8.6 at 74°C. Calcium ion had little inhibitory effect on rate of softening when pH was above 5. Below pH 5 the relative effectiveness of calcium in reducing rate of softening increased as pH decreased. This behavior was opposite to that expected if calcium inhibited softening by cross-linking negatively charged pectin carboxy1 groups. This was more evidence against that mechanism as an explanation for inhibition of softening by calcium ion in plant tissues. A very large decrease in rate of tissue softening was observed at alkaline pH whether or not calcium was added. INTRODUCTIONEFFECTS OF pH on loss of firmness of plant tissues have received a limited amount of attention over the years. Available data indicate that softening is rapid in neutral and very acid conditions with minimum softening in the region of pH 4 (Mattson, 1946;Doesburg, 1961). However, combined effects of pH variation and calcium addition have not been investigated. A very large effect of calcium in inhibiting rate of cucumber mesocarp softening at a pH of 3.2-3.5 has been reported 1990). Multiple lines of evidence based on the ability of various metal ions to affect the softening rate ) have led to the proposal that calcium does not inhibit softening by pectin crosslinking according to the "egg box" model of Grant et al. (1973). The primary idea of the model was that negatively charged polypectate molecules form a gel in the presence of divalent, positively charged calcium ions because the calcium ions fit into ionic sites and cross-link pectate molecules to give a three-dimensional gel structure. The pK of pectin carboxyl groups is about 3.6 (Cesaro et al., 1982). The requirement of ionized carboxyl groups for calcium binding means that maximum softening inhibition by calcium should occur near pH 6, where nearly all free carboxyl groups would be negatively charged. As the pH is lowered, calcium should become relatively less inhibitory due to loss of negative charges as carboxy1 groups become protonated. The main objective of our study was to determine the effect of calcium on softening rate of cucumber tissue as a function of pH to test this prediction of the egg box model. A second objective was to determine the pH range that would minimize loss of firmness for processing of pickled cucumber products with and without added calcium.

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“…The highest decrease in the amount of insoluble fraction and simultaneously the highest increase in soluble fraction were found during treatment of carrot with steam ( Table 3). The changes observed are first of all related to the hydrolysis of cellulose into simpler forms and also transformations of protopectin, e. g., de-esterification [5,6]. An analysis of interactions between carotenoids and insoluble dietary fiber shows that the amount of carotenoids (a-and b-carotene) bound with this fraction decreases during hydrothermal processing.…”

Section: Resultsmentioning

confidence: 98%

“…The situation was quite different in the case of pectins, where thermal processes lead to the formation of pectin-carotenoid complexes (Tables 3, 4). This phenomenon can be explained by the increase in amount of pectins, including de-esterificated forms, which are particularly susceptible to interactions (Table 4), as a result of carrot blanching [5,6].…”

Section: Resultsmentioning

confidence: 99%

“…Pectins are very sensitive to heat treatment, as it can lead to protopectin solution, glycoside bond hydrolysis, releasing of sugar residues bounded with the polygalalacturonic acid chain and de-esterification, i. e., cleavage of ester bonds between carboxyl and methoxyl groups [5,6]. Pectins with a low esterification level can interact with carotenoids, which may deteriorate the color of pressed juices [7].…”

Section: Introductionmentioning

confidence: 99%

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Effect of hydrothermal processing on carrot carotenoids changes and interactions with dietary fiber

Borowska¹,

Kowalska

Czaplicki

et al. 2003

Nahrung

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The aim of the studies was to determine the effect of different methods of heat treatment on carotenoids changes and their interactions with insoluble and soluble dietary fiber. Three industrial varieties of carrot--Simba, Caropak and Fayette constituted the experimental material. Carrot cubes were subjected to heat treatment by putting in water with or without citric acid, or in a convection-type steam furnace. The total content of alpha- and beta-carotene was determined in all kinds of pureed carrots. Its amount bounded with insoluble dietary fiber and pectins was also determined. Changes in soluble and insoluble fractions of dietary fiber during hydrothermal treatment were also determined. It was found that the content of trans alpha- and beta-carotene in carrots decreased significantly (p < 0.05) after heat treatment, compared with the control sample. The loss observed during heat treatment in water was higher (up to 50%) than in the case of a convection-type steam furnace. The highest decrease in the content of insoluble fraction of dietary fiber and the highest increase in soluble fraction were observed after treatment with the use of steam. An analysis of interactions between carotenoids and dietary fiber fractions after hydrothermal processing shows their stronger affinity to forming bonds with pectins than with insoluble fiber. It was also found that the effect of heat treatment parameters was significant--the highest (by six times) increase in the content of beta-carotene bounded with pectins was noted in pureed carrots processed in a convection-type steam furnace.

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Degradation of pectic substances in carrots by heat treatment

Cited by 41 publications

References 8 publications

The thermomechanical properties of carrot cell wall material

The thermomechanical properties of carrot cell wall material

pH Effect on Calcium Inhibition of Softening of Cucumber Mesocarp Tissue

Effect of hydrothermal processing on carrot carotenoids changes and interactions with dietary fiber

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