Kinetics of the thermal degradation of B-Carotene in carrot juice / by Milagros P. Hojilla.

By: Contributor(s): Material type: TextTextLanguage: English Publication details: Indang, Cavite, 1984. Cavite State University- Main Campus,Description: 60 pages : illustrations ; 28 cmContent type:
  • text
Media type:
  • unmediated
Carrier type:
  • volume
Subject(s): DDC classification:
  • 641.35  H68 1984
Online resources: Production credits:
  • College of Agriculture, Food, Environment and Natural Resources (CAFENR)
Abstract: HOJILLA, MILAGROS PARKER. University of the Philippines at Los Banos. October 1984. Kinetics of the Thermal Degradation of 6-Carotene in Carrot Juice. Major Advisers Dr. Virgilio V. Garcia Dr. Leoncio C. Raymundo A study was conducted to quantitatively define the effect of heating on the degradation of 0-carotene in a natural food system. Carrot juice was heated at six (6) temperatures - 104.4°, 110.0°, 115.6°, 121.1', 126.7° and 132.2°C. The concentration of 41-carotene retained after heating for a given time duration was determined using thin-layer Chromatography and the absorbance of the extract was read at 451 nm. The logarithm of pro-vitamin A concentration was then plotted against heating time and thermal resistance parameters, D- and z-values, were graphic-ally determined from the reciprocal of the slope of the graph. The reaction rate constant (k) for each temperature and the activation energy (Ea) for the degradation reaction were also calculated. The destruction of Al-carotene in processed carrot juice was observed to follow first-order reaction kinetics, a behavior typical of most food nutrients and other components. The reaction had an activation energy of 25.6 kcal/mole (107.2 .ICJ/ mole) which was within the average values of Ea for vitamins and related nutrients given by Lund (1977); i.e., 20 to 30 kcal/mole. The other parameters revealed that /1-carotene in carrot juice was not readily destroyed by heat and that prolonged exposure to high temperatures is required to effect considerable degradation of the molecule. An apparent increase in (5-carotene was noted during the Initial stages of heating carrot juice at 104.4°C and 110.0°C. This may be attributed to (a) leaching of the water-soluble constituents into the water which, in turn, increased the relative concentration of the water-insoluble components like ;J-carotene; and (b) possible reversion of cis-isomers to the more stable and more deeply colored all-trans 4i-carotene at the start of heating off Carotene was detected in fresh carrot extracts but not in the heated samples. This indicated greater thermos lability of cc-carotene than 6-carotene and was attributed to the less stable structure of the former due to the lesser number of conjugated bonds in its chromophore.
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Theses / Manuscripts Theses / Manuscripts Ladislao N. Diwa Memorial Library Theses Section Non-fiction 641.35H68 1984 (Browse shelf(Opens below)) Link to resource Room use only T-1321 00006192

Thesis (M.S.--Food Science) University of the Philippines

Includes bibliographical references.

College of Agriculture, Food, Environment and Natural Resources (CAFENR)

HOJILLA, MILAGROS PARKER. University of the Philippines at Los Banos. October 1984. Kinetics of the Thermal Degradation of 6-Carotene in Carrot Juice. Major Advisers Dr. Virgilio V. Garcia Dr. Leoncio C. Raymundo
A study was conducted to quantitatively define the effect of heating on the degradation of 0-carotene in a natural food system. Carrot juice was heated at six (6) temperatures - 104.4°, 110.0°, 115.6°, 121.1', 126.7° and 132.2°C. The concentration of 41-carotene retained after heating for a given time duration was determined using thin-layer Chromatography and the absorbance of the extract was read at 451 nm. The logarithm of pro-vitamin A concentration was then plotted against heating time and thermal resistance parameters, D- and z-values, were graphic-ally determined from the reciprocal of the slope of the graph. The reaction rate constant (k) for each temperature and the activation energy (Ea) for the degradation reaction were also calculated. The destruction of Al-carotene in processed carrot juice was observed to follow first-order reaction kinetics, a behavior typical of most food nutrients and other components. The reaction had an activation energy of 25.6 kcal/mole (107.2 .ICJ/ mole) which was within the average values of Ea for vitamins and related nutrients given by Lund (1977); i.e., 20 to 30 kcal/mole.
The other parameters revealed that /1-carotene in carrot juice was not readily destroyed by heat and that prolonged exposure to high temperatures is required to effect considerable degradation of the molecule. An apparent increase in (5-carotene was noted during the Initial stages of heating carrot juice at 104.4°C and 110.0°C. This may be attributed to (a) leaching of the water-soluble constituents into the water which, in turn, increased the relative concentration of the water-insoluble components like ;J-carotene; and (b) possible reversion of cis-isomers to the more stable and more deeply colored all-trans 4i-carotene at the start of heating off Carotene was detected in fresh carrot extracts but not in the heated samples. This indicated greater thermos lability of cc-carotene than 6-carotene and was attributed to the less stable structure of the former due to the lesser number of conjugated bonds in its chromophore.

Submitted to the University Library 07/18/2007 T-1321

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