Study on the Best Drying Technology of Zanthoxylum bungeanum

Pepper can be dried by natural air drying, hot air drying and microwave drying. However, natural air drying is not suitable for industrial production due to the influence of site and weather conditions. The results show that the quality of pepper dried by hot air is better than that dried by intermittent microwave. The quality of pepper dried by hot air can reach the first level, but the quality of pepper dried by intermittent microwave can only reach the second level. In terms of energy consumption and drying rate, the energy consumption of intermittent microwave drying is only 0.605 KJ/g, drying rate is 7.57 min/g, and the requirement of hot air drying is only 0.605 KJ/g. The energy consumption is 46.443 KJ/g and the drying rate is only 3 min/g. Therefore, we can combine the two drying methods to give full play to their respective advantages, so that we can find a more reasonable way to ensure the drying quality and improve the drying rate and reduce the energy consumption.

According to the experience value and experiment, the hot air drying time of Zanthoxylum bungeanum is still longer when it is spread into thin layer in time, which is not conducive to industrial production. Although the drying time is very short, the quality of products is not good. Intermittent microwave drying has the advantages of fast drying speed and low energy consumption, but due to the heterogeneity of microwave radiation, As a result, the quality of pepper after drying is not very ideal, and the best drying process of pepper can only meet the standard of secondary pepper. It can be seen that the combination of microwave and hot air drying methods can shorten the drying time and ensure the quality of products, which is a way out for pepper drying.

was dried by microwave combined with hot air or hot air combined with microwave. The former used microwave to dry the water content of Zanthoxylum bungeanum to a certain extent, and then changed to hot air drying. Although this method can shorten the drying time, the single product quality is poor. The reason is that the non-uniformity of microwave radiation and its selective heating make different dehydration degree of different parts of Zanthoxylum bungeanum, and some even form Zanthoxylum bungeanum, which affects the sensory quality. This phenomenon is most likely to occur in the case of high moisture content. In addition, microwave irradiation of materials with high moisture content is no different from cooking. On the one hand, microwave irradiation destroys plant tissue structure; on the other hand, it promotes the occurrence of non-enzymatic browning reaction in varying degrees. The combined drying method of hot air and microwave can shorten the drying time and ensure the quality of products. The inhomogeneity of microwave irradiation does not easily make the pepper with low moisture content form oil pepper, so it does not affect the sensory quality of the product. This combination method is called accelerated combined drying, which is a more reasonable drying method than hot air drying and intermittent microwave drying. This combined drying method of hot air and microwave has been applied in some video drying, such as noodle drying.