The stability of the major carotenoids in the pumpkin purees
was expected because the factors that could affect the stability of
these compounds were minimised through processing and storage
conditions. Heat processing is sufficient for the inactivation of enzymes
and micro-organisms which could degrade these compounds.
Moreover, there is a partial vacuum situation inside the
bottle because oxygen is removed from it and that is important
to reduce oxidation reactions. Storage at temperatures lower than
30 C and protection from light are also important factors for the
stability of carotenoids.
In short, the C. moschata ‘Menina Brasileira’ pumpkins showed
good concentrations of a-carotene and all-trans-b-carotene, with
a lower quantity of f-carotene, violaxanthin and lutein, and the
C. maxima ‘Exposição’ pumpkins had the all-trans-b-carotene as
the major carotenoid, with good concentrations of lutein and violaxanthin.
The major carotenoids, which in the case of this present
study were the pro-vitamin carotenes, had relatively high retentions
after the production of the pumpkin purees. A light grade
of isomerisation of b-carotene was detected, with low concentrations
of cis-isomers of b-carotene in both purees. After 180 days
of storage, no significant changes in the contents of these compounds
were noted. Xanthophylls, as lutein and violaxanthin, were
more affected than the carotenes, with significant losses (P 6 0.05)
during processing and storage of the pumpkin purees. Although
these compounds are not precursors of vitamin A, the vitamin
A-inactive carotenoids are being increasingly valued due to their
action against degenerative and cardiovascular diseases, and certain
types of cancers (Azevedo-Meleiro & Rodriguez-Amaya,
2007). New studies which investigate mechanisms of the stability
of carotenoids in food matrix of pumpkin puree, the use of antioxidants,
or which involve alternative technologies for conventional
heat treatment, such as high pressure and the pulsed electric field,
are important to improve the retention of these compounds in
products such as carrots or pumpkin purees, or other vegetables
rich in carotenoids.
The stability of the major carotenoids in the pumpkin pureeswas expected because the factors that could affect the stability ofthese compounds were minimised through processing and storageconditions. Heat processing is sufficient for the inactivation of enzymesand micro-organisms which could degrade these compounds.Moreover, there is a partial vacuum situation inside thebottle because oxygen is removed from it and that is importantto reduce oxidation reactions. Storage at temperatures lower than30 C and protection from light are also important factors for thestability of carotenoids.In short, the C. moschata ‘Menina Brasileira’ pumpkins showedgood concentrations of a-carotene and all-trans-b-carotene, witha lower quantity of f-carotene, violaxanthin and lutein, and theC. maxima ‘Exposição’ pumpkins had the all-trans-b-carotene asthe major carotenoid, with good concentrations of lutein and violaxanthin.The major carotenoids, which in the case of this presentstudy were the pro-vitamin carotenes, had relatively high retentionsafter the production of the pumpkin purees. A light gradeof isomerisation of b-carotene was detected, with low concentrationsof cis-isomers of b-carotene in both purees. After 180 daysof storage, no significant changes in the contents of these compoundswere noted. Xanthophylls, as lutein and violaxanthin, weremore affected than the carotenes, with significant losses (P 6 0.05)during processing and storage of the pumpkin purees. Althoughthese compounds are not precursors of vitamin A, the vitaminA-inactive carotenoids are being increasingly valued due to theiraction against degenerative and cardiovascular diseases, and certaintypes of cancers (Azevedo-Meleiro & Rodriguez-Amaya,2007). New studies which investigate mechanisms of the stabilityof carotenoids in food matrix of pumpkin puree, the use of antioxidants,or which involve alternative technologies for conventionalheat treatment, such as high pressure and the pulsed electric field,are important to improve the retention of these compounds inproducts such as carrots or pumpkin purees, or other vegetablesrich in carotenoids.
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