Red pepper (<i>Capsicum annuum</i> L.) drying: Effects of different drying methods on drying kinetics, physicochemical properties, antioxidant capacity, and microstructure

Deng, Li‐Zhen; Yang, Xuhai; Mujumdar, Arun S.; Zhao, Jinhong; Wang, Dong; Zhang, Qian; Wang, Jun; Gao, Zhen-Jiang; Xiao, Hong‐Wei

doi:10.1080/07373937.2017.1361439

Cited by 212 publications

(175 citation statements)

References 57 publications

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“…The faster drying could be attributed to the synergistic effect of IR drying, that is, rapid heating of material by IR, which increases moisture migration to the surface of the material from inner layers and removal of moisture from the surface by HA drying. A similar trend was observed by Vishwanathan et al () for IR‐HA hybrid drying of carrots, Deng et al () red peppers ( Capsicum annuum L.) Nalawade et al () for bitter gourds and Onwude et al () for sweet potatoes. IR‐HA drying at lower temperatures reduced the drying time significantly as compared to HA drying at similar conditions.…”

Section: Resultssupporting

confidence: 81%

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

Nalawade

Ghiwari

Hebbar

2019

J Food Process Preserv

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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.

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Section: Resultssupporting

confidence: 81%

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

Nalawade

Ghiwari

Hebbar

2019

J Food Process Preserv

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“…The use of pretreatments before hot air drying, such as hot air impingement blanching (Wang et al, ) and pulsed electric fields (Won, Min, & Lee, ) was studied with the aim to decrease the processing time and reduce the changes in products characteristics. Deng et al () compared the conventional hot air drying process with most recent technologies such as pulsed vacuum drying and infrared‐assisted hot air drying; their results indicate that pulsed vacuum drying technology can improve the product quality.…”

Section: Introductionmentioning

confidence: 99%

Characterization of hot pepper spice phytochemicals, taste compounds content and volatile profiles in relation to the drying temperature

Bianchi¹,

Scalzo²

2018

J Food Biochem

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The aim of this study was to investigate how the use of increasing hot air drying temperature affects the phytochemical content and the volatile profile of hot pepper spice. A comprehensive characterization of spice from Italian varieties dried at different temperatures (50, 57, and 64°C) was performed, including general quality indexes, phytochemicals, functional properties, and volatile profile. In dried peppers capsaicinoids were completely retained; a remarkable loss of ascorbic acid was observed, while carotenoids amount decreased of about 39%. The retention of tocopherols was higher at 50 and 57°C. The Folin Ciocalteu index showed a steep decrease after drying, but the opposite trend was observed when it was measured using a correction factor to exclude the ascorbate contribution. The volatile profile changed with the increase in drying temperature, due to the production of Strecker aldehydes, methional, and tetramethylpyrazine, and a reduction in esters, terpenoids, and 2‐isobutyl‐3‐methoxypyrazine. Practical applications Among the processing methods used to produce spice, hot air drying is still the most common. Standard industrial drying process is carried out with air temperatures usually above 70°C, but, in order to enhance the product quality, the processing parameters should be carefully chosen. The appropriate use of lower drying temperatures may increase the retention of phytonutrients and the sensory properties, both aspects which meet the consumers’ expectations. The characterization of spice should be both related to the taste components and to the amounts of phytonutrients and vitamins, very high in hot peppers. The comprehensive results of this study suggest that a better preservation of quality characteristics could be achieved using temperatures under 60°C.

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“…In the case of nonlinear drying curves, method of slope was used to estimate the effective moisture diffusivity ( D eff ) (Deng et al, ; Karathanos, Villalobos, & Saravacos, ; Wang et al, ; Xiao et al, ; Xiao, Gao, Lin, & Yang, ). The experimental drying curve ( MR vs. t ) is compared with the theoretical diffusivity curve ( MR vs. F 0 ).…”

Section: Methodsmentioning

confidence: 99%

“…In the case of nonlinear drying curves, method of slope was used to estimate the effective moisture diffusivity (D eff ) (Deng et al, 2017;Karathanos, Villalobos, & Saravacos, 1990;Wang et al, 2015;Xiao et al, 2012;Xiao, Gao, Lin, & Yang, 2009…”

Section: Effective Moisture Diffusivitymentioning

confidence: 99%

Low temperature plasma pretreatment enhances hot‐air drying kinetics of corn kernels

Chen

Liang

et al. 2019

J Food Process Engineering

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In this study, an efficient method for hot‐air drying of corn kernels was developed through a pretreatment of low temperature plasma. Corn kernels after plasma pretreatment were dried at 37.5, 45, and 52.5°C. It was found that the dried samples with plasma pretreatment presented shorter drying time and higher drying rate. After pretreatment power of 500 W for 30 s at 37.5°C, drying time was shortened by a maximum of 21.52%, and the drying rate was increased by 8.15%. The effective moisture diffusivity is in the range of 1.6107 – 1.9962, 2.8454 – 3.3600, 4.3237 – 4.7171 × 10−11 m2 s−1 at drying temperature of 37.5, 45, and 52.5°C. Plasma pretreatment enhances the drying kinetics more effectively with lower activation energy 47.79 kJ mol−1 in comparison with 54.82 kJ mol−1 for the control group. Atomic force microscopy showed the plasma pretreatment can change the surface topography with some microholes, which explain how the plasma pretreatment can improve the drying process. Practical Application The low temperature plasma pretreatment can improve the efficiency of corn kernels drying. Furthermore, it has potential application for reducing energy consumption in drying. The low temperature plasma pretreatment can be potentially applied in commercial drying.

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Red pepper (Capsicum annuum L.) drying: Effects of different drying methods on drying kinetics, physicochemical properties, antioxidant capacity, and microstructure

Cited by 212 publications

References 57 publications

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

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

Characterization of hot pepper spice phytochemicals, taste compounds content and volatile profiles in relation to the drying temperature

Low temperature plasma pretreatment enhances hot‐air drying kinetics of corn kernels

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