Sarhad J. Agric. Vol.27, No.3, 2011 SENSORY EVALUATION OF MANGO (CHAUNSA) PULP PRESERVED WITH ADDITION OF SELECTED CHEMICAL PRESERVATIVES AND ANTIOXIDANT DURING STORAGE YASSER DURRANI, ALAM ZEB, MUHAMMAD AYUB, WASEEF ULLAH and ALI MUHAMMAD Department of Food Science and Technology, Agricultural University, Peshawar – Pakistan. ABSTRACT Mango pulp was preserved with the addition of potassium sorbate (PS), sodium benzoate (SB) and potassium metabisulphite (KMS) alone and PS in combination with SB and Citric Acid (CA). All the samples were stored at room temperature and were evaluated in sensory evaluation laboratory. It was noted that samples preserved with addition of KMS, PS in combination with KMS and PS in addition with CA retained their overall eatable quality for colour, flavour and odour during 45 and 60 days of storage. Key Words: Mango, pulp, Food preservatives, sensory evaluation Citation: Durrani, Y., A. Zeb, M. Ayub. W. Ullah and A. Muhammad. 2011. Sensory evaluation of mango (Chanunsa) pulp preserved with addition of selected chemical preservatives and antioxidant during storage. Sarhad J. Agric. 27(3): 471-475 INTRODUCTION Mango (Mangifera indica L.) is popular and economically important tropical fruit throughout the world, due to its excellent eating quality (bright colour, sweet taste and luscious flavour) and nutritional composition (vitamins, minerals, fiber and other phytochemical compounds). It is popularly known as ‘The King of Fruits’ (Gerbaud, 2008). According to Agriculture statistics of Pakistan (2008-09) total area under mango cultivation in Pakistan was 170.1 (0000 hectares) with 1727.9 (000 tones) of production. Substantial quantities of mangoes are wasted because of poor post-harvest management and lack of appropriate facilities in developing countries. Development and application of inexpensive preservation techniques to produce high quality and acceptable products of mango could be valuable, allowing a better use of the fruit (Ulloa et al., 2008). Chaunsa variety of mango is known for all over the Pakistan for its sweet taste, attractive yellow colour and reasonable market price during its peak season. Mango pulp is very perishable and has a short shelf life, which both marketers and consumers would like to be longer for this purpose mango pulp is preserved with the addition of selected food additives. Food preservatives are widely added to many foods at the quantity required to control the biochemical changes including the growth of microorganisms and oxidation of vitamins, colorants, flavors etc., according to the amounts specified in food additives legislation (No 95/2 EC, 1995). The major weak organic acid food preservatives include benzoic, acetic, sorbic, and propionic acids. Together with sulfite, these compounds constitute the most widely used acid preservatives in industrial food and beverage production. Sorbic, benzoic acid and sulphur-dioxide are added to foods individually or as mixtures, and their concentrations are up to 0.1% (by food weight), as permitted by legislation (Dong and Wang, 2006; Ping et al., 2009). Fruit pulp could be preserved up to one year at ambient temperature by adding KMS alone (1200 mg/kg) without a significant loss of sensory properties of the fruit pulp (Sonia et al., 2003). There are weak and strong interactions between additives. Sulphur dioxide, ascorbic acid, nitrous acid, sorbic acid and benzoic acid are particularly reactive and commonly used in combined form. They also react with food constituents such as SO2 stabilizes dyes, decolorize pigments, inhibit ascorbic acid oxidation it reacts with sorbic acid in which free radicals OH and O2 oxidise sorbic acid. Sorbic acid is degraded under acidic condition. SO2 also react with artificial sweetners, while benzoic acid requires the presence of a heavy metal catalyst. It should be noted that no adverse effect have in fact been demonstrated in real food that can be attributed to additive interactions (Adams, 1997). Ascorbic acid is usually added to foods to prevent development of oxidative off-flavors and off-color, by reduction of the oxygen in the headspace (Zerdin et al., 2003). Choi et al. (2002) also reported that AA exerts a stabilizing effect on carotenoids. Consumer acceptance is mostly dependant on color of the product (Crisosto et al., 2003) while the perception of sweetness and flavor can even evoke emotional feelings in humans (Bayarri et al., 2001). The overall quality of mango is percepted by the color of the epidermis (González-Aguilar et al., 2001). Sensory analysis of fruit pulps and products is an important tool to correlate physicochemical properties with human perception. By keeping in view the above mentioned facts mango pulp was stored in plastic jars by adding food preservatives individually Yasser Durrani et al. Sensory evaluation of mango with addition of selected preservatives … 472 and in mixtures by not exceeding their concentration more than 0.1% and their effect on mango pulp was organoleptically studied during storage at room temperature. MATERIALS AND METHODS Sample Preparation Fully ripened, sound and healthy mangoes (Chaunsa variety) were purchased from local fruit market in Peshawar and were brought to the Processing Hall of the Department of Food Science and Technology, Agricultural University, Peshawar. Pakistan. The fruits were thoroughly washed with potable water for 5 minutes to remove dirt, dust, pesticide residues and surface microbial load. Peeling and pitting was carried out manually, and pulp was extracted by using pulping machine. Mango pulp samples were prepared by adding potassium sorbate, sodium benzoate and potassium metabisulphite and 0.1% ascorbic acid, either individually or in combination as explained in (Table I). All the samples were individually stored in washed and sanitized plastic jars Sensory Evaluation The main sensory evaluation test for colour, flavour and odour of mango pulp involved 30 semi trained consumers (15 males and 15 females), recruited through personal communication and their willingness to undertake this research. They were all students of Food Science and Technology Department of Agricultural University Peshawar, Pakistan. They evaluated pulp samples during 75 days of storage at room temperature. Each panelist assessed every sample over 15 days interval at sensory evaluation laboratory of the mentioned department by using individual booths with Daylight (100 foot candles). Each consumer evaluated the samples using nine point hedonic scale method as described by Larmond (1977) where 1 represents extremely disliked and 9 represent extremely liked. Table I Experimental plan for mango pulp preservation Treatments PS% SB% KMS% AA% To - - - - T1 0.1 - T2 - 0.1 - - T3 - - 0.1 - T4 0.05 0.05 - - T5 0.05 - 0.05 - T6 - 0.05 0.05 - T7 0.033 0.033 0.033 - T8 - - - 0.1 T9 0.05 - - 0.1 T10 0.1 - - 0.1 T11 - 0.1 - 0.1 T12 - 0.05 - 0.1 T13 0.05 0.05 - 0.1 PS=Potassium sorbate, SB=Sodium benzoate, KMS= Potassium metabisulphite, AA= Ascorbic acid Statistical Analysis Data was analyzed by using Randomized Complete Block Design (RCBD) as described by Gomez (1984) and the means were separated by applying LSD test as described by Steel and Torrie (1997). RESULTS AND DISCUSSION Mango pulp was organoleptically evaluated during storage preserved with the addition of food preservatives. When this research was planned there were only first 7 treatments to be studied during storage for 3 months. With in 3-4 days of storage it was noted that the treatment T4 colour changed and that sample spoiled with in 6 days of storage. A similar study on the sensory evaluation of chemically preserved mango pulp samples confirmed that all the samples tried for organoleptic evaluation were satisfactory up to 270 days except mango pulp preserved with addition of sodium benzoate (200ppm), potassium sorbate (100ppm), (400ppm) and sodium benzoate added in combination with potassium sorbate (200 + 100ppm) during storage at 30-45 °C (Hussain et al., 2003). It is well known that preservative degradation is accompanied by an increase in the concentration of carbonylic compounds which polymerize rapidly to brown pigments affecting food quality (Gliemmo et al., 2001). Sarhad J. Agric. Vol.27, No.3, 2011 473 The research plan was modified and 7 more treatments were prepared including the addition of potassium sorbate and sodium benzoate with the addition of 0.1% synthetic ascorbic acid and all the prepared samples were organoloptically evaluated for colour, flavour and odour. Colour Every food is selected by its visual appearance because colour of food is main attribute for judging the eatable quality of food and same process is applied for the colour of mango pulp in this research. The values for colour of all the treated samples decreased during storage at ambient temperature. The colour of To, T1, T2, T4 and T8 was spoiled and turned black during 15 days of storage interval. The values noted for T3, T5, T6, T7, T9, T10, T11, T12 and T13 were 8.5 to 5.0, 8.6 to 6.3, 8.4 to 1.0, 8.5 to 6.7, 7.8 to 5.6, 8.6 to 6.2, 8.2 to 5.7, 8.2 to 5.5 and 8.3 to 6.7 respectively, during 15 and 45 days of storage intervals. While T10 and T5 were found more stable during 75 days of storage intervals with values of 9 to 5.7 and 5.6. Mean values for all the samples showed an increasing trend from 2.33 for T0, T1, T2, T4 and T8, while it changes interestingly for T6 (4.50), T13 (5.02) T3) (5.62), T11 (5.65), T9 (5.78), T12 (5.82), T7 (6.02), T10 (6.68) and T5 (7.12). All the values were significantly different at p<0.05. These results are in agreement with Gliemmo et al., 2009, where the color stability of pumpkin puree of pH 4.00 and 5.00 stored at 25ºC was studied.