UTILIZATION OF AONLA WASTE FOR PREPARATION OF CIDER AND PROTEIN ENRICHED ANIMAL FEED

Noopur Goel and Neelima Garg

Division of Post Harvest Management

Central Institute for Subtropical Horticulture, Rehmankhera, Lucknow – 227107.

Abstract

Introduction

Aonla is an important fruit crop of India with the production of about . It has high neutraceutical value due to its highest content of vitamin C except Barbados cherry (Shankar, 1969) and presence of stabilizing tannins (Kalra, 1988). The aonla fruits are not good for fresh consumption because of astringency and acidic taste. These fruits are used in huge quantities for making pickles, jam, jellies, shred, preserves, etc. During processing of ripe aonla, of total waste is generated.

The pomace left after juice extraction has low protein content and as such fed to the animals. Keeping this view in mind, an experiment was conducted to utilize the aonla waste (pomace) by solid-state fermentation using baker’s yeast for preparation of cider and protein enriched animal feed. Since aonla pomace has negligible amount of sugar, it was ameliorated with sugar solution.

Materials and Methods

Organism:Saccharomyces cerevisiae was used for preparation of cider and protein enriched animal feed. The culture was maintained on Yeast Extract Peptone Dextrose Agar slants.

Substrate: Aonla pomace (cv. Narendra – 7) obtained from the processing laboratory of CISH was kept under frozen conditions until used. The thawed pomace was sterilized at 1210C, 15 lbs per square inch pressure for 15 minutes in an autoclave.

Sugar Solution: The sugar solution left after aonla fragment preparation was obtained from the processing laboratory of CISH.

Treatments: Following treatments were given to the sterilized aonla pomace.

C→ Uninoculated sterilized pomace mixed with sugar solution (3kg).

A→ 2kg sterilized pomace mixed with 2.75 litres of sugar solution (T.S.S. 740Brix) diluted with equal amount of potable water, inoculated with yeast and kept under anaerobic conditions.

B→ 5.25kg sterilized pomace mixed with 2.5 litres of sugar solution, inoculated with yeast and kept under aerobic conditions in a cylindrical glass jar covered with a loose lid.

The above treatments were kept for fermentation at 18 – 200C for 10 days except control. The pomace of the control was dried at 600C until constant weight was obtained and then ground for nitrogen estimation. After fermentation, the cider was filtered from A with the help of muslin cloth. The pomace left after cider filtration from treatment A and the pomace of treatment B were dried at 600C until constant weight was observed and then ground for estimation of nitrogen.

Analyses: The pomace cider was subjected to various microbiological and biochemical analyses during storage of two months. The tannins, ascorbic acid and non – enzymatic browning were determined using methods as detailed by Ranganna (1997). The reducing sugars were determined using the methods of AOAC (1984). Ethanol concentration in the fermented cider was determined spectrophotometrically by the method as described by Caputi et al. (1968).

The organoleptic evaluation for assigning sensory attributes of the pomace cider was conducted by a panel of seven semi skilled judges by the method as described by Amerine (1965). The attributes considered in the scoring were colour, clarity, nose / aroma, taste, tannin astringency, freedom from acetic acid, sugar and impression. The overall rating was obtained by calculating the average of the scores.

The nitrogen was estimated in the ground pomace as per the microkjeldahl procedure (Herbert et al., 1971).

Results and Discussion

The pomace cider was subjected to various microbiological and biochemical analyses during storage period of two months. No microbial growth was observed in the pomace cider up to two months of storage since the cider was sterilized after filtration and bottling. The reducing sugars content increased during storage of two months whereas the ascorbic acid and tannins content decreased. The non-enzymatic browning increased significantly, due to which the organoleptic score decreased.

Protein enrichment of aonla pomace.

The nitrogen and protein percentages were 1.47 and 9.19 respectively, in the uninoculated ameliorated pomace. The maximum nitrogen and protein percentages (3.01 and 18.81, respectively) were observed in theameliorated pomace, which was given aerobic incubation compared to the pomace which were given anaerobic incubation (nitrogen and protein percentages = 2.66 and 16.63, respectively). This might be because during yeast metabolism under aerobic conditions glycolysis functions in conjunction with tricarboxylic acid cycle wherein the pyruvate generated is oxidized into carbon dioxide and water resulting in better microbial biomass. Under anaerobic conditions, the pyruvate is reduced into ethanol (Tauro, Kapoor and Yadav, 1986).

Table 1. Changes in various biochemical parameters of pomace cider during storage.

Biochemical Parameters / Storage Period (Months) / Critical Difference
0 / 1 / 2
Reducing Sugars (%) / 4.32 / 5.68 / 5.82 / 0.56
Ascorbic acid (mg / 100g) / 43.19 / 34.55 / 14.20 / 9.93
Tannins (%) / 0.97 / 0.95 / 0.88 / 0.04
Non – enzymatic browning / 0.077 / 0.119 / 0.165 / 0.088
Alcohol (%) / 2.1 / 1.2 / 2.1 / -
Sensory Evaluation / 57.2 / 56.8 / 54.5 / -

Table 2. Variation in nitrogen and protein percentages of pomace

Treatments / Nitrogen (%) / Protein (%)
Control (uninoculated ameliorated pomace) / 1.47 / 9.19
Ameliorated pomace under anaerobic incubation / 2.66 / 16.63
Ameliorated pomace under aerobic incubation / 3.01 / 18.81

References:

Association of Official Analytical Chemists (A. O. A. C.) (1970): Official methods of analysis. Washington, D. C., U. S. A.

Caputi, A. Jr.; Ueda, M. and Brown, T. (1968): Spectrophotometric determination of ethanol of wine. Ann. J. Enol. And Viti. 19 : pp.160.

Herbert, C.; Phipps, P.J., and Strange, R.E. (1971): Chemical analysis of microbial cells. In Norris, J. R.; Ribbons, D. W. (eds.) Methods Microbiol. 5 B : pp.209 – 44.

Ranganna, S.(1986): Handbook of analysis and quality control for fruit and vegetable products. 2nd Ed., Tata Mc Graw Hill Pub. Ltd., New Delhi.

Tauro, P.; Kapoor, K.K. and Yadav, K.S. (1986): An introduction to Microbiology. Pub. by Wiley Eastern Ltd.

Shankar,G.(1969):Indian Hortic.,13(4), 9-11,35.

Kalra,C.L. (1988): Indian Food Packer, (7-8), 67-82.