Organoleptic Evaluation and Shelf Life Studies of the Developed Products

Sweet potato (Ipomea batatas L.) is a dicotyledonous plant that belongs to the family convolvulacea. It is a short seasonal crop which reliably provides food on marginal and degraded land with little labor and few or no input outside the farm. The present study revealed that, sweet potato products are good sources of nutrients. Sweet potato chips, flakes and biscuits were prepared by using standard methods. Organoleptic evaluation was conducted. Results revealed that, SC-3 (sweet potato chips), SPF-3 (value added sweet potato flakes) and SB-2 (sweet potato biscuits) scored higher in all the sensory attributes. The nutrient composition of the products contained a good amount of protein, fat, energy, carbohydrate, ash, crude fibre, βcarotene and vitamin-C and also it contains better amount of minerals (potassium, magnesium, zinc, iron, copper, manganese and sodium). Shelf life study was carried out and the products were packed in an aluminium foil bags and kept for initial, 10th, 20th and 30th days of the interval. Results revealed that, the sensory scores for stored products were found to be significantly decreased, and found that, increased the microbial population in all the products, as the number of days increased. Consumer acceptance was conducted for 50 under graduate students of the University which were randomly selected. Results revealed that, the chips, flakes and biscuits were accepted by the consumers respectively. It can be concluded that, the sweet potato products contain appreciable amount of nutrients which can be developed into different products.


INTRODUCTION
The nutritional value of sweet potato with high levels of vitamin A (709 μg) offers an added benefit to processed products. Sweet potato plays an important role in food security, for example, the dried chips can be stored for consumption during the hungry period when some vital crops are in short supply or not available. The bulkiness and perishability of sweet potato storage is a major barrier to the wider utilization of the crop. A possible means of approach to this problem is to diversify the use of sweet potato. Sweet potato roots are being utilized for various products but there is need to further diversify the processing of the roots into more products. Some of the products produced from the processing of sweet potato include fermented sweet potato drink and sweet potato cocktail (Nirvana, 2011). Further diversification of the products of sweet potato is a scientific approach for the supplementation of nutrients for general population.
Various international efforts are being made since long back for alleviating vitamin A deficiency and thereby combating night blindness. From different approaches, mainly supplementation programme, distribution of vitamin capsules; fortification of common foods with micronutrients and the improvement of dietary quality through diversification of foods, and food based approach in achieving and maintaining adequate intake of micronutrient-rich foods. (WHO,1996).

MATERIALS AND METHODS
Organoleptic evaluation of sweet potato products: Sweet potato samples were analyzed for sensory characteristics. Sensory quality characteristics were evaluated by a lab panel of 20 semi-trained members using 9-point Hedonic scale. The samples were evaluated for their appearance, texture, color, aroma/flavor, taste and overall acceptability (ANNEXURE 1). Shelf life study of the sweet potato products Shelf life study was conducted for 30 days using aluminium foil bags which were kepat ambient temperature. The products were observed at the interval of initial, 10, 20 and 30 th days for sensory attributes and microbial load using Nutrient agar (NA) for total bacterial count. The results were recorded. SENSORY EVALUATION SHEET Score sheet for sensory evaluation of sweet potato chips.

EXPERIMENTAL RESULTS
Organoleptic evaluation of the sweet potato products Sweet potato products were kept for sensory evaluation and they were evaluated by semitrained lab panel members using a 9 point Hedonic scale. Mean sensory scores of products were presented in the Table 9, Table  10 and Table11.

Sensory scores of sweet potato chips
The sweet potato chips were subjected for sensory evaluation and the results were presentedinTable-9.The SC3 score dhigherin appearance 8.01 and SC1scoredlowest 7.56. SC3 scored higher in color 8.19 whereas, SC2 scored lowest 7.59. The attribute of the texture scored higher in SC3 8.28 and SC1 scored lowest in texture 7.68. In case of aroma SC3 scored higher 8.14 and lowest 7.69 in SC1. Taste of SC3 scored higher 8.23 and lowest score 7.68 in SC1. However SC3 had higher score in overall acceptability, 8.28 and lowest was SC1 7.86. Among these variations SC3 was selected for shelf life study.  75, 7.30, 7.40, 7.50, 7.55 and 7.40 for appearance, texture, color, aroma/flavor, taste and overall acceptability respectively. Srivastava et al. (2012) reported that, biscuits containing 50 per cent of sweet potato flour was acceptable as it contain higher fibre content and scored high score for overall acceptability.
Singh et al. (2008) reported that, sensory properties of cookies supplementing various proportion of sweet potato flour (0-100 %) to the wheat flour. Sensory evaluation revealed that, increasing levels of sweet potato flour (60 %) lowered the overall acceptability (2.7) because of taste and distinct flavor developed during baking.

Shelf life study of the products
The developed products were packed on Aluminium foil bags and products were kept in ambient temperature. Sensory attributes and microbial load were observed for products at the interval of initial, 10 th , 20 th and 30 th day. Results were revealed as follows.

Shelf life study of the sweet potato chips
Sensory scores of shelf life of the sweet potato chips presented in the Table-12. As the number of the days increased, the scores for the sensory characteristic decreased in the products. The result found that from initial day to till the 30 th day. The scores of appearancedecreasedfrom8.45to6.20, texture8.40 to 6.15, color 8.40 to 5.57, aroma 8.05 to 5.75, taste 8.00 to 5.90 and overall acceptability 8.05 to 5.90. There was significant difference was found in all the sensory attributes at 5 per cent.
As the number of the days increased, the scores for the sensory characteristic decreased in the products. The result found that from initial day till the 30 th day. The scores of appearance decreased from 8.45 to 6.20, texture 8.40 to 6.15, color 8.40 to 5.57, aroma 8.05 to 5.75, taste 8.0 to 5.90 and overall acceptability 8.05 to 5.90. Schwartz et al., 2006, reported that, sweet potato Frenchfry type products were observed in the sensory scores for color, flavor and texture thus indicating that the products has good stability in storage. Shelf life study of the value added sweet potato flakes Sensory scores of shelf life of the value added sweet potato flakes presented in the Table- Table-14. The sensory attributes are reduced from initial to 30 th day. The sensory scores of the appearance decreased from 8.45 to 6.90, texture 8.08 to 6.01, color 8.50 to 7.89, flavor 8.29 to 6.98, taste 8.09 to 6.78 and overall acceptability 8.01 to 6.54.There was significant difference in all the sensory characteristic except color which was non-significant at 5 per cent. The sensory attributes are reduced from initial to 30 th day. The sensory score of the appearance decreased from 8.45 to 6.90, texture 8.08 to 6.01, color 8.50 to 7.89, flavor 8.29 to 6.98, taste 8.09 to 6.78 and overall acceptability 8.01 to 6.54. It was observed that, after the 30 th daybiscuitslosthardness. This may be due to the absorption of moisture although it was packed in an aluminium foil bags. Taneya et al. (2014) reported that, there were no changes in texture and flavor on storage of 90 days Microbial study of sweet potato chips Total bacterial population in sweet potato chips product of (SC3) at initial, 10 th , 20 th and 30 th days of storage are presented in Table-15. Bacterial population of SC3 at initial, 10 th , 20 th and 30 th day was found to be 0.00, 3.20, 4.80 and 6.90X10 4 respectively. It was found that, as the storage period increased microbial population was also found to increase. Total bacterial population in sweet potato chips 3 at initial, 10 th , 20 th and 30 th days of storage are presented in Table-15. Bacterial population of SC3 at initial, 10 th , 20 th and 30 th day was found to be 0.00, 3.20, 4.80 and 6.90X10 4 respectively. Microbial study of value added sweet potato flakes Table-16 depicts the population of total bacteria in value added sweet potato flakes 3. Bacterial population of SPF3 at initial, 10 th , 20 th and 30 th days was found to be 0.00, 2.90, 4.30 and 5.90 × 10 4 respectively. Table-16 depicts the population of total bacteria in value added sweet potato flakes 3. Bacterial population of SPF3 at initial, 10 th , 20 th and 30 th days was found to be 0.00, 2.90, 4.30 and 5.90X10 4 /gm respectively.

Microbial study of sweet potato biscuits
Total bacterial population in sweet potato biscuits 3 at initial, 10 th , 20 th and 30 th days of storage presented in Table-17. The bacterial population of SB2 at initial, 10 th , 20 th and 30 th days was found to be 0.00, 3.20, 5.40 and 7.40 × 10 4 respectively. Total bacterial population in sweet potato biscuits 3 at initial, 10 th , 20 th and 30 th days of storage presented in Table-17. The bacterial population of SB2 at initial, 10 th , 20 th and 30 th days was found to be 0.00, 3.20, 5.40 and 7.40X10 4 /gm respectively. Oluwalana et al. (2012) reported that, five blends were prepared by homogenously mixing sweet potato flour with wheat flour in the percentage proportions of: 0:100, 5:95, 10:90, 15:85 and 100:0 (PF:WF) and later used to bake bread. The microbiological results of the bread ranged from 1.0X10 3 to 4.0X10 3 cfu/g of product.

SUMMARY AND CONCLUSION
Organoleptic evaluation of the sweet potato products were evaluated by 20 semi-trained panel members using a 9 point Hedonic scale. The products were evaluated for appearance, color, texture, aroma/flavor, taste and overall acceptability. Overall acceptability of the sweet potato chips, value added sweet potato flakes and sweet potato biscuit sranged from 8.28 to 7.86, 8.25 to 7.75 and 8.10 to 7.40 respectively.
Shelf life study was conducted for a period of 30 days. The sweet potato products were packed in aluminium foil bags and kept at ambient temperature. Observation was recorded for sensory attributes for 10, 20 and 30 days interval. It was observed that from initial to 30th day, the overall acceptability decreased ranged between 8.05 to 5.90 in SC3, 7.90 to 6.85 in SPF3 and 8.03 to 6.54 inSB2.
The sensory score for stored products were found to be significantly decreased, and also increased microbial population in all the stored products was observed as the number of days increased.