Microwave drying of selected greens and their sensory characteristics

Development of instant paneer type product from groundnut using microwave dehydration

The present study aimed at the development of a groundnut-based dehydrated paneer type product which could serve as an instant vegan protein source. In the process of preparing groundnut paneer, a ratio of 1:5 of groundnut to water and 2.0% calcium chloride (CaCl₂) solution was used for the preparation of groundnut paneer and the product was evaluated for physicochemical, instrumental color, instrumental textural, and sensory characteristics. The developed paneer cubes (1.5 × 1.5 × 1 cm) were dehydrated using a vacuum-assisted microwave dryer at different microwave powers (200-600 W, 250 mbar vacuum). The minimum bulk density (0.55 g/cc) and maximum rehydration ratio (2.9) were recorded in the sample dehydrated at 600 W. The samples dried at 600 W also showed significantly (p < .05) higher L* values, softer texture and high sensory scores for color, aroma, taste, texture, and overall acceptability after rehydration.

Coriandrum sativum L.-Effect of Multiple Drying Techniques on Volatile and Sensory Profile

Coriandrum sativum L. is a medicinal and aromatic plant spread around the world, with beneficial properties that are well recognized. Both coriander seeds and leaves are used for pharmaceutical and flavoring purposes. Even though coriander seeds tend to be more popular, the leaves are receiving a consistently growing interest, especially because of popularization of Mexican, Northern African, and Indian cuisines. This increased attention brings about the necessity for providing the product with guaranteed quality, which will retain its valuable characteristics, even after post-harvest treatment. For this reason, it is highly necessary to determine reliable protocols for cilantro preservation, which usually include drying procedures; in order to identify the optimal drying treatments, a spectrum of drying techniques-convective, vacuum-microwave, and a combination of convective and vacuum-microwave-were evaluated. Cilantro-based dried products were examined from the perspectives of volatile organic constituent composition and sensory quality. After headspace solid-phase microextraction-GC/MS analysis and sensory tests, the results demonstrate that convective drying at 70 °C for 120 min followed by vacuum-microwave drying at 360 W and convective drying at 70 °C were the optimal drying methods for preserving cilantro aroma quality, while convective drying at 70 °C for 120 min followed by convective finishing drying at 50 °C decreased cilantro aroma quality.

The rehydration behavior of microwave-dried amaranth (Amaranthus dubius) leaves

The effect of temperature (35, 50, and 60°C) on the rehydration behavior of microwave-dried amaranth (Amaranthus dubius) leaves was investigated. Leaves were dried at 700 W power level before rehydrating in water. The higher the rehydration temperature, the higher the equilibrium moisture content of the leaves, although the effect was not statistically significant. The increase in rehydration ratio was significant only as temperature increased from 50 to 60°C. The process was adequately described by the Peleg sorption model, with the Peleg rate constant (K₁) and the Peleg capacity constant (K₂), both decreasing as rehydration temperature increased. While the color difference (ΔE) between fresh leaves and leaves rehydrated at 35°C was significantly higher than for the leaves rehydrated at 50 and 60°C, this difference was not visible. Cooking of leaves occurred beyond 120 min at the higher rehydration temperatures . Based on the results, rehydration of microwave-dried leaves was successfully carried out at 35°C, however, rehydrated leaves were darker than the fresh leaves. Increasing the temperature to 50°C improved the rehydration capacity and the color of the leaves, however, cooking of leaves occurred by the second hour of the process.

Microwave Food Processing

Consumers prefer food products with enlarged shelf life, which are quick to prepare, healthy and fresh like. Traditional food processing methods are based on intensive heating and as a result cause quality loss. Minimal processing techniques such as microwaves approach consumer's demands to create fresh like products with enlarged shelf life. Microwave technology can be very useful for food processing, because products are heated directly instead of conventional heating by convection and conduction. This means a reduction of the total processing time, no overheating on the outside of the product, and preservation of the fresh product quality. This chapter presents a complete picture of current knowledge on application of microwave in food processing which has been used for different processes like blanching, sterilisation, thawing, drying and extraction of various products. In many cases combinations with microwaves gave the best results.