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|Authors:||DESAI, MEGHA VENKATESH PRABHU|
|Title:||STUDIES ON JUICE MAKING IN BER (Zizyphus mauritiana Lamk)|
|Publisher:||Mahatma Phule Agricultural University Rahuri 413 722.|
|Abstract:||The present investigation was carried out to standardize the stage of fruit maturity and juice extraction method to obtain maximum ber juice recovery of acceptable taste. Three maturity stages viz. mature-green, golden yellow and turning-brown; and four extraction methods viz. blanching, cold extraction, pre-cooling, pre-cooling + enzymic extraction were studied. To improve the organoleptic qualities of uice, techniques such as clarification, blending with sugar, acid andsynthetic essences were also tudied. The juice was evaluatedfor changes in chemical constituents and organoleptic qualitiesduring the torage at ambient and low temperatures.The fruit size (weight, length and diameter) increasedwhile weight of seed decreased as the fruit maturity advanced. T.S.S., T.S.S. : acid ratio, reducing and total sugars, ascorbic acid and pH increased while acidity, non-reducing sugars and tannin content decreased as the fruit maturity advanced. The golden yellow stage, as compared to mature-greenand turning-brown stages, was found to give higher recovery of raw as also of clarified juice. The sediment content of the raw juice decreased and the viscosity of raw and clarified juice increased as the fruit maturity advanced. The higher meanorganoleptic score was recorded for the juice obtained from golden yellow fruits as compared to the fruits of other two stages. The colour of the juice was also influenced by fruit maturity. Golden yellow fruits produced yellow coloured raw juice and attractive lemon yellow coloured clarified juice. T.S.S., T.S.S : acid ratio, reducing and total sugars, ascorbic acid and pH were higher, while acidity, non-reducing sugars and tannin content were lower in the clarified juice obtained from fruit of increasing maturity. As regards the method of extraction, pre-cooling +enzymic extraction yielded higher raw and clarified juice (61.53and 30.23 per cent, respectively) with higher mean organolepticscore (5.25) of clarified juice. Pre-cooling + enzymic extraction had lower sediment content of raw juice and also lower viscosity of raw andclarified juice as compared to remaining three methods. Thecolour of the juice was not influenced by extraction methods except blanching, which induced slight browning. Chemical composition of clarified juice was influenced by extraction methods. Blanching and pre-cooling + enzymicextraction increased the T.S.S., reducing and total sugars overthat of control (cold extraction). The latter also increasedacidity over that of control. The loss of ascorbic acid washighest (27.40%) in pre-cooling + enzymic extraction.The interaction between stage of fruit maturity andmethod of xtraction revealed that fruits of golden yellow stageextracted by pre-cooling + enzymic extraction produced highest juice recovery (68.90 and 34.40 per cent of raw and clarifiedjuice, respectively) with highest mean organoleptic score ofclarified juice (5.44). However the score indicated only marginal acceptability probably due to higher astringency. Hence the juicewas treated by gelatin and casein. In general, gelatin treatment improved the juice recovery and lowered the tannin contentconsiderably. Treatment of 1.0 g gelatin/litre was the mosteffective and also improved the recovery of clarified juice by13.00 per cent over control and decreased the tannin content ofjuice by 84.4 per cent. It also scored highest organoleptic score (5.49), however, it was still lower than acceptable level. For beverage reparation the juice composition of 50% and 37.5 % and brix level of 20° was found to be ptimum.Blending with Cardamom essence (0.125 ml/100 ml of juice) wasfound to improve flavour. Fortification of ber juice with citricacid to give 0.5, 0.6 and 0.7 per cent acidity and ascorbic acid@ 100 and 200 mg/l00g was found to be beneficial in producing hebeverage of desirable organoleptic quality.The juice with 0.6% acidity, 20 °Brix, 100 mg ascorbic acid/100 g and Cardamom essence @ 0.125 ml/100 ml when convertedinto ready-to-serve beverage by 50% dilution and readjusting theBrix to 20° , was most preferred by the judges with a meanorganoleptic score of 8.09 followed by the juice with 0.7 % acidity, 20°Brix, 100 mg ascorbic acid/100 g and Cardamom essence@ 0.125 ml/100 ml, when converted into ready-to-serve beverage ofabove dilution.During the storage of ber juice at ambient temperature(30 to 33°C) and low temperature (8 to 10°C), T.S.S., T.S.S :acidratio, non-reducing and total sugars, ascorbic acid, pH andtannin content decreased while acidity and reducing sugarsincreased. The changes were more pronounced at ambient temperature than at low temperature. Browning of the juice was noticed at the end of 6 weeks and the intensity of browning was more at ambient temperature than at low temperature. Increase in acidity and ascorbic acid during fortification slowed down changes in chemical constituent ofstored juice. Changes in chemical constituents were slower injuice with 0.7 % acidity and 200 mg ascorbic acid/100 g juice.However, the browning of the juice increased with increase in thelevels of acidity and ascorbic acid.Storage of the juice lowered the organoleptic score ofbeverage prepared from it during 12 weeks storage, however, the decrease was slower at low temperature than at ambienttemperature. The juice at ambient temperature lost itspalatability at the end of 12 weeks storage due to severe browning.|
|Appears in Collections:||Thesis|
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