Process efficiency of electromagnetic radiation (EMR)‐assisted hybrid drying in spearmint ( Mentha spicata L. )

Abstract

Spearmint (Mentha spicata L.) leaves were dried using four different methods, namely, infrared‐hot air (IR‐HA) drying, radiofrequency‐hot air (RF‐HA) drying, low‐humidity air (LHA) drying, and hot air (HA) drying at three different temperatures (30, 40, and 50°C). The effect of the methods on time required for drying, product quality in terms of chlorophyll, total carotenoids, essential oil yield and its composition, color, browning index (BI), and rehydration ratio was evaluated. The IR‐HA hybrid drying at 50°C resulted in faster process with nearly 62% lesser drying time, as compared to HA drying, and also resulted in higher retention of essential oil (85.7%), carvone (79.6%), and lower BI (50.4). The specific energy requirement of IR‐HA hybrid drying reduced by 60% as compared to HA drying at 50°C. The results showed that hybrid drying involving IR could be effectively used to obtain good quality of dried spearmint leaves in a shorter time with better energy efficiency. Practical applications Spearmint is popular for essential oil, and carvone is the major volatile compound present in the oil, giving its characteristic odor. This study explored the effect of drying methods (IR‐HA, RF‐HA hybrid drying, and LHA drying) on drying characteristics, quality of dried spearmint and its comparison with HA drying. The study showed that IR‐HA drying resulted in shorter processing time with a higher yield of essential oil, carvone retention, and energy efficiency than other drying methods. The results indicated that IR‐HA hybrid drying technique could be explored as an alternative to HA drying of heat‐sensitive herbs like spearmint.

Volatile compounds, bioactive properties and chlorophylls contents in dried spearmint (Mentha spicata L.) as affected by different drying method

“…However, Uribe et al ( 2016) determined a range of 0.76-0.89 mg g -1 DW for dried Mentha piperita by vacuum drying at different temperatures (50-90 °C), a lower range than the amount in the three sample types. Another study (Nalawade et al 2019) reported the total Chl content in a cultivar of fresh spearmint (Mentha spicata) leaves to be 4.09 mg g -1 DW and that the percentages of retention of this content in samples following different drying methods ranged between 38.97-61.12%.…”

“…This aromatic and herbal spice is utilized globally in flavoring, pharmaceutical, cosmetic and fragrance applications. Additionally, they can be used in fresh or dried forms, and as essential oils (Nalawade et al 2019). Spearmint is often used in many cuisines and the food industry mainly due to its distinct aroma.…”

“…The specific aroma of spearmint is generally derived from certain terpenoid compounds (Da Porto & Decorti, 2009). The qualitative and quantitative composition of these compounds are affected by pre-and post-harvest conditions (Nalawade et al 2019). Drying processes particularly change the profile of VC depending on temperature, humidity and time conditions (Korkmaz et al 2020;İzli & Polat 2020;Polat et al 2021).…”

Infrared Drying Trends Applied to Fruit

“…Another important component to verify the conservation of quality is the color that the product or food takes after the drying process. Some authors identified that the color is quite preserved in the product, which is very important in its marketing (Cheng et al, 2019;Nalawade et al, 2019;Zhao et al, 2019). The infrared drying method also provides a faster operating time compared to other drying methods while maintaining compositional and sensory characteristics at high levels (Ebrahim et al, 2019;Hasan et al, 2019;Qu et al, 2019;Zeng et al, 2019).…”

Thin-layer drying characteristics, modeling and quality attributes of tomato slices dried with infrared radiation heating

“…Infrared drying as a substitute drying technique for food has many advantages. These may involve less drying period, high energy efficiency, and temperature materials in standard finished products with high quality (Nalawade et al 2019). Numerous food products…”