M.N. Ramesh

Influence of processing parameters on the drying of spice paprika.

Abstract Paprika is utilized for its strong colour and has very little pungency. The quality of ground paprika is mainly determined by its seasoning power i.e., capsaicin content its natural colour i.e., carotenoid content, its particle size and water content. Selection of proper drying conditions is necessary for minimizing thermal stress, over-drying and maintenance of relevant compounds which determine the quality of the product. Loss of red colour is caused by autoxidation of the carotenoids. It is reported that the stability of the quality of paprika, during storage is dependent on drying conditions and the degradation rate of quality increases as the drying temperature increases. In view of the importance of this spice product standardization of processing protocol is necessary. Transport properties in terms of interphase mass and heat transfer along with the diffusion coefficient were determined for paprika from drying experiments. The analysis includes the comprehensive process including the form of the product like whole fruit or pericarp, various preprocessing steps like cutting, separating, steam blanching and drying. Drying was carried out using both a conventional pilot scale convective dryer and a laboratory dryer with the additional facility of drying under inert atmosphere. For processing under inert gas, the pre- and post-drying steps of cutting, separating and grinding the product before storage were also carried out under inert conditions The influence of these pre-processing steps on the drying behaviour was characterized by determining the transport properties. Additionally, the product was also analyzed for its red colour intensity (ASTA) value, tocopherol, carotenoids and vitamin C content, to evaluate the best possible processing protocol to obtain a good quality product.

Studies on inert gas processing of vegetables

Abstract During the last years the nutritional importance of antioxidants in food, e.g. carotenoids, tocopherols and vitamin C, has been recognized because of their possible role in the prevention of human diseases such as cancer, atherosclerosis and immune depression. During normal industrial processing – including cutting, blanching, drying and storing – vegetables usually suffer distinct losses in these components, resulting in a significant quality decrease. Applying low oxygen conditions during critical processing steps yields products of better quality. Results of a comparative study of atmospheric and inert gas processing of three vegetables are presented.

Retrofitting of a vertical retort for on-line control of the sterilization process

Abstract A micro-controller-based retort control system for sterilization of foods was developed. The feature of this developed control system is that actual container cold point temperature is sensed on real time basis using temperature sensors. The on-line temperature is further processed using software to determine the sterilization value in terms of F o and is continuously displayed. The sterilization process is controlled until the set F o value is attained and at the end of the heating process cooling is automatically started. This ensures commercial sterility leading to higher nutrient retention and savings in energy by avoiding overcooking. This system can be easily incorporated onto the existing manually controlled batch retorts – horizontal or vertical. The system is more economical than the large sophisticated computer controlled systems presently available. It is mainly aimed at small and medium scale food processing industries having manually operated batch retorts.

Biphasic model for the kinetics of vegetable cooking at 100 °C

Abstract The biphasic model was applied for determining the time domains in which the two reaction rate constant operate. The point of changeover was determined at which the slopes of the two reaction rate constants intersect. These changeover points were at 6, 8 and 10 min of cooking at 98 ± 2 C, for green peas, carrot and knol-khol respectively. It was interesting to note that radish did not have any changeover point. These observations also confirmed the findings of earlier work, that there are two substrates S 1 and S 2 which provide skeletal rigidity to the vegetables. These findings are important to decide the operating parameters in the blanching of vegetables as preprocessing.