Infrared Assisted Freeze-Drying (IRAFD) to Produce Shelf-Stable Insect Food from Protaetia brevitarsis (White-Spotted Flower Chafer) Larva

In this study, the potential of infrared assisted freeze-drying (IRAFD) was tested for the production of shelf-stable edible insects: Protaetia brevitarsis larva (larva of white-spotted flower chafer). The IRAFD system was customized using an infrared lamp, K-type thermocouple, controller, and data acquisition system. The infrared lamp provided the sublimation energy for rapid freeze-drying (FD). The IRAFD conditions were continuous IRAFD-5.0 kW/m² and IRAFD-5.0 kW/m² at different weight reduction (WR) (10%, 20%, and 30%). The continuous IRAFD reduced the drying time to 247 min compared to the 2,833 min duration of FD (p<0.05). The electrical energy could be reduced by more than 90% through infrared radiation during FD (p<0.05). The Page model resulted in the best prediction among the tested drying kinetic models. In terms of quality, IRAFD showed significantly lower hardness, chewiness, and higher protein levels than hot air drying and FD (p<0.05). IRAFD better preserved the glutamic acid (6.30–7.29 g/100 g) and proline (3.84–5.54 g/100 g). The external product appearance after IRAFD exhibited more air pockets and volume expansion, which might result in a good consumer appeal. In conclusion, this study reports the potential of IRAFD in producing shelf-stable and value-added edible insects.

Ohmic cooking of instant rice cake soup: energy efficiency and textural qualities

The potential of ohmic heating was investigated to cook instant rice cakes according to electric field strengths (9, 12, 15, 18 V/cm) and cooking times (60, 80, 100, 120 s). Customized ohmic heating system was equipped with ohmic cell, electrodes, thermocouple, proportional-integral-differential controller and data acquisition system. Heating rate significantly increased when electric field strengths increased. Heating rate was 12.1 °C/min at 9 V/cm, and was increased to 38.8 °C/min at 18 V/cm. The energy efficiency was evaluated in terms of system performance coefficient (SPC) energy efficiency. The best SPC energy efficiency was 0.65 at an electrical field strength of 18 V/cm. An electric field strength of 15 V/cm and an 80 s cooking time resulted in the most preferable hardness (7.73 N). Ohmic heating would be applicable to cook instant rice cakes, resulting in good energy efficiency and textural qualities.

Evaluating the Feasibility of Ohmic Cooking for Home Meal Replacement Curry: Analysis of Energy Efficacy and Textural Qualities

The feasibility of ohmic heating was tested for cooking instant home meal replacement (HMR) curry mixture. A curry mixture (curry powder, spam, carrot, potato, and water) was ohmically heated to 100 °C using different electric fields (9, 12, 15, and 18 V/cm). Temperature come-up time to 100 °C of curry soup were 5.27 ± 0.63, 3.15 ± 0.39, 2.28 ± 0.19, and 1.67 ± 0.24 min at the electric fields of 9, 12, 15, and 18 V/cm, respectively. The come-up time was decreased as a function of enhanced electric fields (P < 0.05). In terms of energy efficacy, the highest electric field (18 V/cm) resulted in the most efficient system performance coefficient (SPC), with a score of 0.62. In terms of textural qualities, cooking at 15 V/cm of carrot and potato the hardness was 3.41 ± 0.69 N and 1.04 ± 0.18 N, respectively, that resulted in the ideal level of hardness. Our study proposed the positive feasibility of ohmic heating to cook HMR curry soup.