The color stability of pumpkin (Cucurbita moschata, Duchesne ex Poiret) puree of pH 4.00 and 5.00
containing potassium sorbate (KS), ascorbic acid (AA) or their mixture, packaged in polyethylene and in
polyvinyl chloride–polyvinylidene chloride copolymer (PCPC) bags, was analyzed throughout the storage
at 25 C. Color changes were measured through lightness (L), redness (a), yellowness (b). Changes in
a and b were mathematically modeled. In general, lightness, redness and yellowness diminished with
storage time. The presence of KS diminished color loss of purees packed in PCPC bags and increased the
discoloration of purees contained in polyethylene suggesting, in the first case, that KS oxidation diminished
the available oxygen protecting carotenoids oxidation, and in the second case, the existence of
a coupled oxidation between KS and carotenoids helped by the oxygen presence. Addition of AA to
a puree of pH 4.00 containing KS and packed in polyethylene minimized the losses of redness and
yellowness; probably as a consequence of the antioxidant action of AA. The increase in pH from 4.00 to
5.00 in the presence of KS significantly minimized color degradation of puree packed in PCPC. From the
point of view of improving color stability, a convenient formulation could be a puree of pH 5.00 preserved
with KS and packed in PCPC.
The color stability of pumpkin (Cucurbita moschata, Duchesne ex Poiret) puree of pH 4.00 and 5.00containing potassium sorbate (KS), ascorbic acid (AA) or their mixture, packaged in polyethylene and inpolyvinyl chloride–polyvinylidene chloride copolymer (PCPC) bags, was analyzed throughout the storageat 25 C. Color changes were measured through lightness (L), redness (a), yellowness (b). Changes ina and b were mathematically modeled. In general, lightness, redness and yellowness diminished withstorage time. The presence of KS diminished color loss of purees packed in PCPC bags and increased thediscoloration of purees contained in polyethylene suggesting, in the first case, that KS oxidation diminishedthe available oxygen protecting carotenoids oxidation, and in the second case, the existence ofa coupled oxidation between KS and carotenoids helped by the oxygen presence. Addition of AA toa puree of pH 4.00 containing KS and packed in polyethylene minimized the losses of redness andyellowness; probably as a consequence of the antioxidant action of AA. The increase in pH from 4.00 to5.00 in the presence of KS significantly minimized color degradation of puree packed in PCPC. From thepoint of view of improving color stability, a convenient formulation could be a puree of pH 5.00 preservedwith KS and packed in PCPC.
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