STORAGE STABILITY OF STRAWBERRY JAM COLOR ENHANCED WITH BLACK CARROT JUICE CONCENTRATE
ABSTRACT Black carrot juice concentrate was added to enhance the color of strawberry jams prepared from two locally grown cultivars, Osmanlı and Kara. Compared to other cultivars processed to jams, these two cultivars are lightly colored but very aromatic. Color and pigment stability of colored and noncolored (control) strawberry jams were studied during storage. The use of black carrot concentrate as a source of natural colorant stabilized the color of strawberry jam. The stabilization was more noticeable for jams prepared from Osmanlı cultivar. Monomeric anthocyanin degradation was fitted to a first-order reaction model. Storage temperature had a strong influence on anthocyanin degradation. As the storage temperature increased, the stability of anthocyanins decreased significantly in both colored and noncolored jams. Parallel to decrease in monomeric anthocyanins, hue (h°) values of all jam samples increased throughout the storage. However, increase in h° values was much smaller in colored samples than in noncolored samples. High correlation was found between h° value and anthocyanin concentration at 22C (r = 0.910–0.978) and 37C (r = 0.931–0.981).
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ABSTRACT: Strawberry purées were prepared using a commercial polygalacturonase (PG) and a highly purified pectinesterase (PE) preparation, respectively. To elucidate the effect of pectin on color stability following enzymatic pulp maceration, pectin composition was studied by isolating and fractionating the alcohol-insoluble residue from the strawberry purées. The purées were stored at +20 and +4 °C in the dark over a period of 24 weeks monitoring the amounts of monomeric and polymeric anthocyanins as well as antioxidant activities (FRAP, TEAC). Individual anthocyanins were analyzed by HPLC–DAD–MSn , and color measurements were obtained in the CIE L*a*b* system. Pectin composition was significantly modified following enzymatic maceration of the purées. While PG treatment generally resulted in pectin losses, oxalate-soluble pectins were increased in PE-treated purées. After 24 weeks of storage, the best anthocyanin retention was observed in PE-treated purées. Such products also revealed greatest anthocyanin half-life values and lowest proportion of polymeric pigments. Compared to an untreated control, enzymatic purée maceration using the PG was also beneficial for pigment retention, but less effective than PE. In contrast, color and antioxidant activity were independent of both enzymatic treatments. An initial heating step (90 °C, 10 s) for immediate inactivation of native enzymes such as polyphenoloxidases slightly improved pigment stability, while lowered temperature during mash maceration was less effective. However, by far best color and pigment retention were achieved when the purées were stored at 4 °C in the dark.European Food Research and Technology 234(2). · 1.39 Impact Factor
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ABSTRACT: In the food industry, browning and colour alteration are usually the main problems to solve in red juices. In an attempt to ease complications due to pomegranate juice processing, the combination of thermal treatment, storage at selected temperature and blending of juices was assessed as a novel and combined solution. A pure monovarietal juice, a combination of two widely distinct varietal juices (75 % Mollar de Elche + 25 % Wonderful) and a blend of pomegranate juice plus lemon (75 % + 25 %, respectively) were compared after pasteurization at two different heat treatments (high temperature–short time (HTST) and low temperature–long time (LTLT)). The effect of processing on the bioactive composition and colour parameters was monitored during juice shelf-life at two storage conditions (room and refrigeration temperatures). The reaction kinetics of main phytochemicals and a factorial analysis were also performed in order to achieve comprehensive data on the evolution of juice quality during storage. Results displayed how blending can protect the desirable properties of pomegranate juices better than pure monovarietal juices. Likewise, a high specificity between thermal treatment and kind of juice was found for each considered parameter. HTST exhibited a higher protective role than LTLT for blends of varietal pomegranate juices, whilst LTLT seemed to protect mixtures with lemon much better than HTST. Moreover, the concomitant degradation of anthocyanins and vitamin C and their role in colour variations were exposed. Overall, the array of outcomes might provide a satisfactory solution of colour alteration in pomegranate juices as well as red fruits in general.Food and Bioprocess Technology 11/2013; · 4.12 Impact Factor