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2016 - 20172
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Subject: Microbiology × Author: Manmeet Kaur × End date: 2018 × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Enzymatic debittering and aroma enhancement of kinnow juice
    (Punjab Agricultural University, Ludhiana, 2017) Manmeet Kaur; Sahota, Param Pal
    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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    ThesisItemOpen Access
    Optimization, production and partial purification of βglucosidase from yeast using citrus peel
    (Punjab Agricultural University, Ludhiana, 2016) Manmeet Kaur; Sahota, Param Pal
    The enzyme β-glucosidase hydrolyzes cellobiose and short chain cello-oligosaccharides to glucose. The study was conducted to evaluate the production of enzyme β-glucosidase using economically viable substrate citrus fruit waste with optimized batch scale fermentation using Clavispora lusitaniae strains KF633446 and KP131848.1 as yeast inoculum. The process parameters optimized during study are: substrate concentration (117.9g/L lemon peel powder or 46.875 g/L lime) or 16.8 g/L banana peel powder, temperature (35°C) and pH (5) , inoculum concentration of 0.75% v/v, time period of 36 h and 30h using yeast strains KP131848.1 and KF633446 respectively. Use of citrus fruit waste as substrate for enzyme production has proved to be economical; the maximum enzyme activity 0.49 IU/ml with lemon peel, followed by lime (0.28 IU/ml) and banana peel (0.337 IU/ml). The enzyme activity (IU) of β-glucosidase after partial purification was found to be 18.52 IU. The partially purified β-glucosidase was highly stable at temperature 45°C and pH 5. The value of Km and Vmax was 1.25mM and 17.98 IU/ml respectively using pNPG (para-nitrophenyl-β-Dglucopyranoside) as substrate. The addition of enzyme @ 0.4 ml per 100 ml of juice resulted in increased reducing sugar content in sweet lime juice (58.42%), grapefruit juice (57.36%), lemon juice (55.26%) and kinnow juice (53.19%), with storage time period of 15 days. Sensory analysis on 9 point hedonic scale revealed maximum score of 8.4±0.2 for aroma and 7.85±0.25 for flavour of lemon juice. This study revealed the commercial utilization of peel as substrate for β-glucosidase production and wide applicability of β-glucosidase enzyme in aroma and flavor enhancement along with debittering properties of enzyme Naringinase and Limonin dehydrogenase.