A mathematical model to predict the shelf life of gulabjamun mix based on moisture‐induced spoilage by stickiness (caking) and nonenzymatic browning (NEB) was developed. The moisture adsorption isotherms of gulabjamun were determined at 10, 25 and 40C. The water vapor permeabilities of the packaging materials were also calculated. The critical moisture contents for stickiness and NEB to occur were determined and the moisture‐limiting shelf life was predicted. Validation of the prediction model was done by accelerated shelf life testing at 38C and 90% RH. At 4.8% moisture content, the experimental shelf life of gulabjamun mix based on stickiness and NEB was observed respectively as 41 and 54 days in low‐density polyethylene (LDPE) and 280 and >360 days in polyethylene terephthalate (PET)/Al foil/PET/LDPE pouches. The corresponding predicted values were 34 and 46 days in LDPE and 247 and 342 days in PET/Al foil/PET/LDPE, respectively. The simulation model was fairly accurate and reliable in predicting the shelf life of this product. Practical Applications Stickiness and nonenzymatic browning reactions, induced by moisture gain, affect the shelf life of gulabjamun mix. For dry powders like gulabjamun mix, having a regular shelf life of 6–12 months, accelerated shelf life testing (ASLT) is cumbersome and sometimes unfeasible. Simulation and mathematical modeling of shelf life is an alternative to long‐term ASLT. In this study, a model for predicting the shelf life of gulabjamun mix was developed, incorporating the water vapor permeability of the packaging material, the adsorption of moisture from headspace of the package and the weight of moisture in the product. The shelf life prediction will be useful to monitor the product quality and stability against deteriorative reactions. The model could also be used for shelf life estimation of new products in flexible packaging materials.

Mathematical models were developed for the heat and mass transfer phenomena during deep‐fat frying of gulab jamun, a dairy dessert popular throughout the Indian subcontinent. Size, shape, core temperature, moisture and fat contents of the product were monitored at regular intervals during 8 min of frying. The heat transfer was described using both lumped capacity model and transient heat conduction equation. As the calculated Biot number for lumped capacity model was greater than 0.1, the convective heat transfer coefficient was determined using the transient heat conduction equation as 122.34, 116.12 and 94.10 W/(m2 K) at 135, 145 and 155C, respectively. The moisture transport was described using a partial differentiation equation analogous to the transient heat conduction. The moisture transfer coefficient, ranging from 10.41 × 10−6 to 14.35 × 10−6m/s, increased linearly with frying temperature. The Lewis number declined from 0.96 to 0.54 with increasing temperature, indicating that at higher frying temperatures moisture diffusivity gained predominance over thermal diffusivity. Fat uptake of the product followed fractional conversion first‐order kinetic model. Practical Applications Gulab jamun, a popular dairy sweet of the Indian subcontinent, is processed by deep‐fat frying of milk solids–starch dough balls, followed by soaking them in sugar syrup. Its manufacture is currently dominated by small‐scale unorganized enterprises, leading to non‐optimized process conditions and widely varying product quality. The present study aims at describing the heat, moisture and fat transfer during the deep‐fat frying process of this product using mathematical models. The effects of process parameters, such as temperature and time, on thermal and mass transfer properties and diffusivities were evaluated. Such mathematical models provide information to food processing professionals that help in predicting and optimizing the frying process parameters of gulab jamun in order to achieve maximum energy efficiency and desired product quality.

Indian cottage cheese (paneer) whey (6.39% total solids [TS]) was vacuum concentrated to 15 and 26% TS levels and utilized in wheat bread manufacture. The bread prepared from the dough incorporated with 26% TS concentrated paneer whey (CPW) was yellowish and possessed a firm and “crumbly” crumb which was least accepted. Whereas, the bread prepared from 15% TS CPW dough was cream colored, and displayed acceptable sensory quality with an overall acceptance score of 7.32/9.0. CPW (15% TS) incorporation enhanced loaf volume by about 62 mL, but the disadvantage was that it considerably slowed down the dough proofing time, almost by two times. Three methods were suggested to restore proofing time, viz. enhanced water level in the dough, enhanced fermentation temperature (40C) and enhanced yeast level (6%). Satisfactory proofing time could be obtained using any of these methods. The shelf life of the bread remained unaffected by whey incorporation. PRACTICAL APPLICATIONS Indian cottage cheese, commonly known as paneer, is widely popular in the Indian subcontinent. It is produced and marketed on a large scale by various government and privately run dairies. Its manufacture involves coagulating the hot milk by citric acid, filtering out the coagulum, pressing the coagulum in a stainless steel press for 15–30 min and dipping the pressed coagulum in chilled water (5–10C) for 1–2 h. This process results in the generation of large quantities of whey as a byproduct. It is a common practice for the dairies to release the whey directly into the drainage system without any pretreatment. This leads to enormous pollution in the areas surrounding the dairies, and also puts load on effluent treatment plants. It also results in enormous losses in terms of valuable nutrients like lactose, proteins and minerals, which developing countries like India and Pakistan cannot afford to lose. In this background, studies on effective utilization of whey assume importance. This project is aimed at developing a suitable technology for complete utilization of whey in wheat bread manufacture. The outcome of the study is significant for small‐scale bakers in the Indian subcontinent because it offers a technology to prepare common bread utilizing whole whey. Utilization of whey in this manner not only enhances nutritive value of bread, but also helps in mitigating the problems of whey disposal at industry level.

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 β-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.

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.