Sorption and thermodynamic properties of dry crystallized Palada payasam mix prepared using manual and mechanical stirring.

An attempt was made to develop mathematical models to describe the sorption behaviour and determine the thermodynamic properties of sorption of dry-crystallized Palada payasam mix at different water activities (between 0.113 and 0.973) and temperature ranging from 25 to 35 °C. Samples were prepared using both manual and mechanical mixing during the crystallization process and the equilibrium moisture content (EMC) was recorded using the isopiestic technique to compare the sorption behaviour of both samples. The sorption isotherms were found to follow a J-shape-type III plot, with the sorption capacity decreasing with temperature. The isotherms also exhibited a typical temperature inversion of EMC at water activity > 0.70. The sorption data obtained was fitted to 12 mathematical models for sorption and the Guggenheim, Anderson and de Boer (GAB), Peleg and Iglesias and Chirife models were found to describe the data over the entire range of water activity with a good fit. The isosteric heat of sorption and spreading pressure were determined as a function of moisture content. Isosteric heat of the samples was computed and found to decrease from 51.75 to 47.16 kJ/mol for control (manually stirred) and 49.38 to 47.58 kJ/mol for experimental sample (mechanically stirred) for a range of moisture content up to 29% (d.b). The spreading pressures increased with increasing water activity but decreased with increasing temperature. No significant difference was observed between the sorption properties of the dry crystallized samples prepared using manually and mechanically stirring.

Studies on effect of oat and cheese incorporation on sensory and textural quality of short-dough type biscuit.

In view of their growing importance in human nutrition, incorporation of oats and cheese during the manufacture of short-dough type biscuits was studied. Rolled oats were incorporated at 25, 35 and 45 % of refined wheat flour in short-dough type biscuit formulation. Cheddar and processed cheese were used for flavouring purpose at three levels each, viz. 30, 40 and 50 % on flour basis. The dough exhibited less firmness on oats incorporation as indicated by lower firmness value (21.73 N) as against 25.05 N for control dough measured by Texture Analyser. Addition of cheese to the 25 % oat incorporated dough further reduced its firmness and altered its viscoelastic characteristics. Baking conditions for the oats and cheese incorporated biscuits were optimized as 165 °C for 25-27 min. Sensory evaluation results revealed that the biscuit made from 25 % oat incorporated dough scored highest in most of the sensory attributes including overall acceptability. Cheddar cheese and processed cheese levels were optimized at 30 and 40 % in oats-incorporated dough based on the sensory analysis of biscuits prepared from the dough samples. The moisture and ß- glucan contents were 3.93 % and 0.62 %; 4.32 % and 0.60 % for cheddar cheese and processed cheese added biscuits, respectively. The spread ratios were higher in cheese incorporated biscuits than in oat incorporated biscuits. It was concluded that good quality cheese flavoured biscuits can be prepared by incorporating rolled oats in biscuit formulation along with cheddar or processed cheese.

Studies on the effect of preservatives on physico-chemical, microbiological and sensory quality of kunda.

Kunda, an indigenous heat desiccated sweet product prepared from milk and added sugar, has a shelf-life of a few days under market conditions. In this study, effect of preservatives viz. potassium sorbate and nisin on the shelf-life of kunda stored at 30° and 5 °C was investigated. During storage, several changes took place in physico-chemical and sensory characteristics, the changes being faster at 30° than at 5 °C. There was little effect of preservatives per se on the quality of kunda, but changes were slower in kunda preserved with nisin. Kunda packaged in LDPE pouches or tin cans and stored at 30° and 5 °C, irrespective of the presence or absence of preservatives, was stable for 42 and 90 days respectively. Increase in osmotic pressure due to high levels of sugar in kunda might be responsible for containing the growth of microbes in the product.

Study on the effect of packaging materials on the physico-chemical, microbiological and sensory quality of kunda.

Kunda, an indigenous heat desiccated sweet product prepared from milk and sugar, has a shelf-life of a few days under market conditions. In this study, shelf-life of kunda packed in select packaging materials viz. LDPE, metallised polyester and tin cans and stored at 30° and 5 °C was investigated. During storage, several changes took place in physico-chemical and sensory characteristics, the changes being faster at 30 °C than at 5 °C. The storage study indicated that kunda was acceptable throughout the storage period of 42 days at 30 °C and 90 days at 5 °C, irrespective of packaging material. However, the rate of changes in characteristics of the product packaged in tin cans and metalized polyester was slower. Hence, it was recommended that kunda be packed in tin cans and metallised polyester pouches which possess high barrier properties for achieving long shelf-life.

Extended shelf life flavoured dairy drink using dissolved carbon dioxide.

Cardamom flavoured dairy beverage prepared using standardized method was carbonated in glass bottles. Carbonation at 50 psi pressure for 30 s was recommended. The pasteurized flavoured drink, carbonated or otherwise was evaluated for sensory, chemical and microbial quality during its refrigerated storage. The uncarbonated control samples were found to be sensorily acceptable up to 14 days, while the carbonated beverage remained acceptable up to 30 days. Carbonation of drink significantly affected the pH and acidity of product without reducing its acceptability. Carbonation resulted in inhibition of microbes, the effect was pronounced on psychrotrophic count. There was a linear but marginal increase in the pH of the carbonated samples till the 17(th) day of storage; the values diminished thereafter. The carbonated samples also had significantly reduced contents of FFA and soluble nitrogen compared to that of uncarbonated control samples as storage progressed beyond 10 days and this was attributed to inhibited microbial growth.

Carbonated fermented dairy drink - effect on quality and shelf life.

Processing conditions were standardized for a carbonated sweetened fermented dairy beverage. The optimum level of carbonation for the beverage filled in 200 ml glass bottles was found to be at 50 psi pressure for 30 seconds. The beverage samples were stored under refrigerated conditions (7 °C) and evaluated at weekly intervals for their sensory, chemical and microbial quality. The uncarbonated control samples were found to keep well till 5 weeks of storage while the carbonated beverage was acceptable up to 12 weeks of storage. Carbonation did not significantly alter the pH of the beverage, while a marginal increase in titratable acidity was recorded for the carbonated samples. Carbonation was found to arrest the development of lipolysis and proteolysis in the beverage during storage. Microbiological investigations established the inhibition of yeast and mold growth due to dissolved CO2.