Optimisation of process variables for value added pumpkin (cucurbita moschata poir) products.

Abstract

The present study entitled “Optimisation of process variables for value added pumpkin (Cucurbita moschata Poir.) products” was undertaken to standardise the process variables for value added dehydrated products of pumpkin such as sweet and salted flakes and ready to use custard powder. The study also aimed to evaluate the nutritional and organoleptic qualities and shelf life of the products.

The percentage of weight loss, solid gain and water loss increased gradually in dehydrated sweet and salted flakes with increase in concentration of the solute upto four hours of soaking. Fluctuations in the above mentioned parameters were noticed in the fifth and sixth hours of soaking. In sweet flakes, maximum sucrose gain was noticed in flakes prepared from pumpkin slices soaked in 60 per cent sugar solution. The salted flakes prepared using 15 per cent salt solution had the highest percentage of salt gain.

The organoleptic qualities of dehydrated sweet and salted flakes and custard were evaluated. Sweet flakes prepared from pumpkin slices soaked in 60 per cent sugar solution containing 0.3 to 0.4 per cent citric acid had maximum mean scores of above 8.00 for different quality attributes. The mean scores for different oragnoleptic qualities of salted flakes was found to be high in flakes prepared by soaking in three per cent salt solution containing 0.3 per cent citric acid for one hour. Among seven treatments tried, custard prepared from custard powder having 5 to 20 per cent pumpkin and 15 to 30 per cent corn flour had maximum mean scores for different quality attributes.

Sweet flakes prepared from pumpkin slices soaked in 60 per cent sugar and 0.3 per cent citric acid solution for two hours and salted flakes prepared from pumpkin slices soaked in three per cent salt solution containing 0.3 per cent citric acid for one hour were selected as the most acceptable treatments. For the preparation of ready to use custard powder, the treatment having 10 per cent pumpkin powder and 25 per cent corn flour was selected as the most acceptable one.

The selected custard powder was evaluated for various physical qualities. The custard powder was freely flowing without any lumps even after three months of storage. Bulk density of the product was found to be constant (0.72g per ml) throughout the storage period.

The moisture content and titrable acidity of sweet and salted flakes and custard powder increased during storage, whereas a reduction in pH was noticed during storage. Due to inter conversion of biological components, the reducing sugar, total sugar and TSS showed a decreasing trend in all the three products. A decrease in β carotene content was also noticed during three months of storage.

The enhanced moisture absorption during storage slightly decreased the crispness of flakes thereby affecting their acceptability. The mean scores for different organoleptic qualities of sweet and salted flakes decreased during three months of storage. The custard prepared from custard powder was acceptable throughout the period under study.

Microbial count was not observed in sweet and salted flakes initially. But on storage, microbial contamination was noticed from first month onwards. In custard powder, bacterial and fungal growth was not observed throughout the storage period but yeast count of 0.33x103 cfu g-1 was observed at the end of three months of storage. Insect infestation was not observed in custard powder throughout the storage period.

Cost of production of dehydrated sweet and salted flakes and custard powder was computed and was found to be slightly higher than the flakes and custard powder available in the market.