Enzymatic debittering and aroma enhancement of kinnow juice
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Date
2017
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Punjab Agricultural University, Ludhiana
Abstract
The processing of acidic fruits to beverages has encountered commercial restrictions due to
development of delayed and inherent bitterness by limonoids and flavonoids. The present
study has been undertaken with purified debittering enzymes; limonin dehydrogenase,
naringinase and β-glucosidase to meet the consumer palatability of citrus juices. The limonin
dehydrogenase enzyme has been purified to 1.14- fold with 33.98% recovery, 29.25 IU
activity and 0.525 IU/mg specific activity resulted in 86.43% degradation of limonin in
juice by catalyzing oxidation of limonin –A-ring lactone to the non-bitter 17dehydroxylimonoate.
The debittering naringinase enzyme 24.8IU activity,0.442 IU/mg
specific activity, purified to1.68 fold could reduce 57.93% naringin which is hydrolysed by
the enzyme into non-bitter bioactive compound naringenin.. The flavour enhancing βglucosidase
with activity 14.68 IU, specific activity 0.344 IU/mg purified to 1.18 fold
resulted in the increase in glucose content upto 4.25µg/ml in kinnow juice. The debittered
fermented low alcoholic naturally carbonated (LANC) beverage has been developed by
optimizing the bioprocess conditions as TSS 13ºB, yeast inoculum @ 0.75%(v/v), incubation
temperature 28±2ºC and time 36hrs.The physicochemical changes were recorded as TSS
13ºB, acidity 0.313%, naringin 181.13 ppm, limonin 4.73 ppm, glucose 1.3µg/ml, total sugars
42.97 µg/ml, ascorbic acid 34.22 mg/ml in fermented kinnow beverage after 25 days of
storage at 4ºC. In kinnow juice, maximum reduction in bitter component limonin 87.34%,
naringin 58.41% whereas increase in glucose upto 4.38 µg/ml, acidity 30.13% and total sugar
content 42.97 µg/ml were observed. The nutraceuticals recorded in fermented kinnow
beverage were flavonoids (mg/L)- gallic acid 0.075, caffeic acid 0.002, rutin 0.001, ferulic
acid 0.001; Organic acids (mg/L) – oxalic acid 0.243,tartaric acid 3.698, mallic acid 0.018,
citric acid 0.432; Fat soluble vitamins (mg/L)-Vitamin A (Retinol) 0.060, cholecalciferol (D3)
0.038, α-tocopherol (Vitamin E) 0.001, Vitamin K 0.018 ; water soluble vitamins (mg/L)thiamine
0.782, pyridoxine hydrochloride 0.040, pantothenic acid 0.002, riboflavin 0.001,
biotin 0.011; Protein 6.42g/100g,Carbohydrate 40.95g/100g.
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