Optimization, production and scale up of debittered kinnow beverage by and #945;-L-rhamnosidase producing yeast

Pratiksha Singh,Rajesh Singh,Param Sahota,Fatima Bhadra

doi:10.9755/ejfa.184383

Abstract

α-L-Rhamnosidase is used for debittering the citrus juice by hydrolyzing bitter naringin to nonbitter prunin and rhamnose. The present study was carried out on fermentative production of debittered kinnow (Citrus reticulata Blanco) beverage using α-L-rhamnosidase producing yeast in order to utilize its immense potentiality in processed kinnow juice industry. The effect of percent yeast inoculum concentration (0.25-1.25 v/v), total soluble solids (12-16 °B), temperature (15-35 °C) and incubation time (12-60 h) were studied to optimize the production of α-L- rhamnosidase enzyme from Clavispora lusitaniae in kinnow juice. Results indicated that yeast showing maximum rhamnosidase activity (0.056 IU mL-1) in presence of yeast inoculum concentration (0.75% v/v), brix (13 °B), temperature (30±5 °C) and incubation time (48 h). Further, these optimized conditions were used in upscale production of debittered kinnow beverage. The physicochemical parameters of freshly prepared beverage TSS 13.00±0.20 °B, acidity 0.14±0.03%, pH 3.40±0.10, brix acid ratio 92.85±0.00, limonin 6.90±0.10 ppm, naringin 443.00±10.00 ppm, total sugars 12.90±0.30%, reducing sugars 2.42±0.20 and ascorbic acid 27.80±1.00 mg/100 mL. All the physicochemical parameters did not change significantly during storage. The decrease of naringin with storage was 443.00±10.00 to 143.70±4.00 ppm due to the α-L-rhamnosidase activity of yeast. The percentage of ethanol and CO2 were 0.89±0.05% and 1.46±0.06 bar after three months of storage. All the sensory parameters like taste, color, aroma, bouquet, flavor and astringency of kinnow beverage were stable at storage period of 90 days with almost no change in organoleptic sensation. Thus the technology presented here, a very less time consuming and safe for production of debittered kinnow beverage on large scale in citrus food industries.

Highlights

India is the second largest producer of fruits, with a production of 44.04 million tonnes of fruits from an area of 3.72 million hectares and holds third rank in respect of production of citrus fruits in the world
Screening of juice components for optimization of α-L-rhamnosidase production Effect of percent inoculum concentration on α-Lrhamnosidase Five different concentration of inoculum, 0.25%, 0.5%, 0.75%, 1% and 1.25% (v/v) of the standard stock inoculum was added in the juice and incubated for 24 h at room temperature
A differential response in rhamnosidase activity was obtained which showed that the 0.75% inoculum concentration exhibited maximum enzyme activity i.e. 0.057 IU mL-1 and 0.25% exhibited minimum rhamnosidase activity i.e. 0.023 IU mL-1 in kinnow juice (Fig. 1)

Summary

Introduction

India is the second largest producer of fruits, with a production of 44.04 million tonnes of fruits from an area of 3.72 million hectares and holds third rank in respect of production of citrus fruits in the world. A hybrid of Citrus nobilis and Citrus delicosa is a prevalent citrus fruit in Punjab covering an area of 46,000 hectares with the production of 9.88 lakh tones NHM (2014). Kinnow juice turns bitter after extraction due to chemical naringin (flavanoid) and limonin (limonoid). Naringin is the major component in citrus fruit with very bitter taste and a threshold of 20 mgKg-1 in water and detectable limit less than 1.5 mgKg-1 (Chen et al, 2010). The presence of limonin and naringin in excess of 6 ppm and 600 ppm respectively has been established as an objectionable level of bitterness in processed citrus products such as juice, wine and vinegar (Guadagni et al, 1973)

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