Pilot scale processing of red flesh guava RTS beverage S. Bhuvaneswari and R. B. Tiwari Division of Post Harvest Technology Indian Institute of Horticultural Research Hessaraghatta Lake (P.O), Bangalore-560 089, India E-mail: bhuvana@iihr.ernet.in ABSTRACT Pilot scale studies on production of ready-to-serve (RTS) beverage from red flesh guava were done using 100 kg of the fruit. Pulp yield was more (73.68 %) in lye peeling than in hand peeling (58.68 %). RTS beverage was prepared by mixing fruit pulp with syrup to an optimum level of acidity and sugar, as standardized on a laboratory scale. Blending RTS beverage by using colloidal mill improved the colour, consistency and overall quality. From 100 kg of red flesh guava, 247 litres of RTS beverage could be obtained. The cost:benefit ratio and value addition from this process were worked out at 1.79 and Rs. 5.45/kg of fruit, respectively. Key words: Exotic red flesh guava, RTS beverage, pilot scale, colloidal mill, cost:benefit ratio, value addition INTRODUCTION Guava is one of the most important fruits, valued for its high vitamin C content. It is widely grown in India under an area of approximately 0.15 Million hectares producing 1.8 MT (Anon. 2000). Use of guava fruits in processed products such as jam, jelly, nectar (Kalra and Tandon, 1984), beverage (Kalra et al, 1987), blended RTS beverage and cheese (Singh et al, 1983) is well established and several commercial products are being marketed. In general, both white and pink flesh guava fruits have good market value for fresh consumption. However, these fruits can also be used for processing. Pink varieties are better suited for beverage preparation owing to their attractive colour. An exotic red flesh guava variety, with high acidity, attractive colour and good flavour was earlier identified as the raw material for production of RTS beverage (Tiwari and Dinesh, 2001). Fruit juice based RTS beverages have the distinct advantage of higher nutritional value over synthetic aerated waters. Hence, pilot scale studies on preparation of RTS beverage from the high acid red flesh guava were undertaken as this is a prerequisite for commercialization of the product. Results of the pilot scale production trial are detailed in this paper. MATERIAL AND METHODS Fully ripe, exotic red flesh guava, harvested from the IIHR orchard was used for scale-up trial. RTS beverage was prepared by subjecting 100 kg fruits to the following unit operations. Washing and preparation Fruits were manually washed thoroughly using a jet of clean, running water. Hand - peeling with a stainless- steel knife and lye peeling using 3% NaOH solution were carried out. Pulping and sieving Peeled guava slices were pulped using a Wareing blender (Make: KenStar Excellence) @ 10 kg/h. The pulp was sieved using a rectangular sieve of size 33 cm x 27.5 cm x 15 cm with 1/32" thick stainless-steel wire mesh to separate seeds from the pulp. RTS beverage preparation RTS beverage was prepared by using 15% pulp and adjusting TSS to 18o Brix with sugar syrup and 0.3% acidity. Thorough blending of RTS beverage was done using a colloidal mill (Make: CM 305/94). Bottling and pasteurization The RTS beverage was pasteurized at 80oC and bottled in 200ml sterilized, dry bottles using a power- operated bottle filling machine @ 300 bottles/h. Bottles were corked manually, using a hand-operated crown corking J. Hort. Sci. Vol. 2 (1): 50-52, 2007 machine @ 240 bottles/h. Filled bottles were batch - pasteurized and stored at room temperature (28 – 30oC). Quality evaluation in RTS beverage Total Soluble Solids (oBrix) was determined using Erma Hand Refractrometer. Acidity(%) and ascorbic acid (mg/100ml) content were determined using standard procedures (Ranganna 2000). Viscosity (cps) was measured using Brookefield Viscometer fitted with spindle No.18 and at a spindle speed of 60 rpm. Non-enzymatic browning was measured using a spectrophotometer by measuring absorbance at 440nm (Ranganna, 2000). Sensory evaluation Sensory evaluation of RTS beverage was done by a panel of 25 semi-trained judges using a 9-point hedonic scale with scores from ‘Like extremely” to “Dislike extremely”(Ranganna, 2000). Storage quality RTS beverage was stored at room temperature (25oC-30oC) for 6 months and samples were analyzed for their composition at monthly intervals during the storage period. RESULTS AND DISCUSSION In guava, fruit skin constitutes a minor portion of the fruit and loss due to peeling the skin varies with the method applied. Use of lye solution in peeling several fruits and vegetables is common (Khurdiya and Srivastava, 1994). Hence, fruits were subjected to lye-peeling and were compared hand-peeling. Peeling loss and pomace recovery was lower in lye-peeling when compared to hand-peeling. Time required for peeling was reduced by 50 % in lye peeling when compared to hand-peeling. In lye-peeling, pulp yield (73.68 %) and peeling rate (20kg/person/h) was higher when compared to hand-peeling (58.68 %) and (12kg/person/h), respectively (Table 1). From the results it is obvious that lye peeling is advantageous over hand peeling in terms of pulp yield and peeling rate. Pulping and blending of RTS beverage In a pilot scale preparation of RTS beverage, manual mixing is laborious and time- consuming. Hence, blending of ingredients was attempted using a colloidal mill. Quality of the final product was compared to that from the manual method. From these studies, it was found that viscosity, ascorbic acid content and colour retention in the RTS beverage was more when colloidal mill was used for blending as compared to manual mixing (Table 2). It was also observed that blending in colloidal mill improved the colour, consistency and ascorbic acid content in the final product. This may be due to re- circulation of the juice which could have resulted in the reduction of particle size in the pulp thereby improving product quality. These results are similar to studies on homogenized tomato juice by Thakur et al (1995) . Storage studies of red flesh guava RTS beverage Change in composition of the red fleshed guava RTS beverage over 6 months storage period at ambient conditions is shown in Fig 1. TSS and acidity ranged between 16 –18.2 oBrix and 0.26-0.3 %, respectively. There was a gradual increase in viscosity Optical density of the juice indicating non-enzymatic browning increased with storage period Similar results were observed Table 1. Peeling characteristics of exotic red flesh guava Parameters Hand peeling Lye peeling Weight of fruit (kg) 50 50 Number of persons 2 1 Time required for peeling (min.) 180 90 Peel content- fruit basis (%) 26.88 17.98 Average peeling rate (kg/person/h) 12 20 Pulp yield- fruit basis (%) 58.68 73.68 Pomace recovery- fruit basis (%) 13.44 7.46 Table 2. Quality parameters of red flesh guava RTS beverage Parameter Manual Blending mixing in colloidal mill TSS (o Brix) 18 18 Acidity (%) 0.30 0.30 Ascorbic Acid (mg/100ml) 4.55 5.85 pH 3.48 3.48 Viscosity (cps) 12.80 16.70 Overall Sensory Score(9 points) 6.17 7.35 Fig 1 Storage studies on red flesh guava RTS beverage J. Hort. Sci. Vol. 2 (1): 50-52, 2007 51 Pilot scale processing ofguava by Shrestha and Bhatia (1982) during apple juice storage. Ascorbic acid content decreased from 9.75 to 3.5 mg/100ml during 6 months of storage. Reduction in ascorbic acid content during storage has been reported in amla (Mehta and Rathore, 1976), lemon (Palaniswamy and Muthukrishnan, 1974) and in citrus juices (Mehta and Bajaj, 1983). Cost economics of pilot scale production of red flesh guava RTS beverage Guava fruit @ Rs. 10/kg Rs. 1000.00 Sugar @ Rs. 20/kg Rs. 700.00 Bottles @ Rs.2 / bottle (200ml) Rs. 2000.00 Labour charges @ Rs.107/day Rs. 1950.00 Chemicals Rs. 100.00 Total Rs. 5750.00 Overhead charges (Electricity, operation of equipment and machinery) @ 20 % of total Rs. 1150.00 Grand Total Rs. 6900.00 RTS beverage output (litres) 247.0 Cost of production/litre Rs. 27.95 Selling price of RTS beverage @ Rs. 50/litre Rs. 12, 350.00 Selling price of guava @ Rs. 10/kg Rs. 1000.00 Profit/litre Rs. 22.05 Cost:Benefit 1: 1.79 Value addition/kg guava Rs. 5.45 / kg Cost economics was worked out based on actual expenditure incurred during production ACKNOWLEDGEMENT The authors are thankful to the Director, IIHR, Bangalore and project leader Shri. E. R. Suresh for encouragement and providing facilities to carry out the research. Help rendered by Dr. T. M. Gajanana, Sr. Scientist (Agril. 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