Continuous microwave drying of germinated brown rice: Effects of drying conditions on fissure and color, and modeling of moisture content and stress inside kernel

Shen, Liuyang; Wang, Lei; Zheng, Chun-Hou; Liu, Chenghai; Zhu, Yong; Liu, Hui; Chai, Linna; Shi, Yongkun; Zheng, Xianzhe; Xu, Haozhe

doi:10.1080/07373937.2019.1705331

Cited by 34 publications

(24 citation statements)

References 52 publications

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“…Moreover, the "Severe" fissure degree of brown rice kernels started appearing in HA/RF45 and dramatically increased at HA/RF55 and the maximum value was observed at HA/RF60. This result showed that RF heating affected the fissure percentage significantly due to the high absorption of RF energy inside the rice kernels, which was also reported by Shen et al [4]. The overall temperature of germinated brown rice kernels was improved to form a greater moisture content gradient because of the high absorption of microwave energy inside the kernels.…”

Section: Fissure Percentagesupporting

confidence: 82%

“…The effects of different RF heating temperature conditions on the fissure percentage of brown rice kernels with different fissure degrees are shown in Table 2. The fissure percentage was divided into four groups, namely None (0 fissure), Few (1-2 fissures), Moderate (3-4 fissures), and Severe (>5 fissures), as reported by Shen et al [4]. The morphology of fissures in white rice with different fissure degree is shown in Figure 5.…”

Section: Fissure Percentagementioning

confidence: 96%

“…Radio frequency (RF) and microwave (MW) are electromagnetic waves within the frequency ranges of 1-300 MHz [2] and 300 MHz-300 GHz [3], respectively. They have been widely used for drying agricultural products, such as rice [4][5][6][7], soybean [8], walnut [9], barley malt [10], macadamia nut [11], tea leaves [3], etc. RF and MW treatments, as a kind of dielectric heating method, involves the generation of heat as a result of the interaction between an electromagnetic field and polarized molecules in the crops that are either of bipolar or ionic nature [12].…”

Section: Introductionmentioning

confidence: 99%

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Quality of Milled Rice from Large-Scale Dried Paddy Rice by Hot Air Combined with Radio Frequency Heating

Chitsuthipakorn

Thanapornpoonpong

2021

Processes

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A scaled-up process for paddy drying was developed using hot air (HA) combined with radio frequency (RF) heating. The study was conducted using hot air (control treatment) arranged in descending order in four temperature levels, namely 80 °C at moisture content of 25–26%, 70 °C at moisture content of 20–25%, 60 °C at moisture content of 17–20%, and 50 °C at moisture content of 13–17%, as well as with hot air combined with radio frequency (HA/RF) at different paddy temperatures (45–60 °C) by adjusting the appropriate RF energy when passing through RF heating chamber, namely HA/RF45, HA/RF50, HA/RF55, and HA/RF60. Each treatment was performed in three replicates and data were statistically analyzed in a randomized complete block design. The quality attributes of paddies affected by the drying process were assessed: fissure percentage, color, milling quality, and sensory evaluation. The drying efficiency showed that the drying time and the specific energy consumption could be decreased by up to 54.44% and 23.17% at HA/RF60 and HA/RF45, respectively. As the RF heating temperature increased, the fissure percentage of brown rice kernels at HA/RF45 and HA was not significantly impacted. Regarding color evaluation, combining RF heating and convective drying at all given conditions could be statistically applied in terms of the b*, WI, and ΔE* value. Considering the milling yield of HA as the baseline, head rice yield was maximized at HA/RF45, while bran yield reached the maximum at HA/RF60. The liking score of cooked rice after it was dried using the HA method was the highest. This study concludes that the HA/RF45 was the most appropriate drying condition, and this may provide preliminary exposure to the industrial drying of paddies.

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Section: Fissure Percentagesupporting

confidence: 82%

Section: Fissure Percentagementioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Quality of Milled Rice from Large-Scale Dried Paddy Rice by Hot Air Combined with Radio Frequency Heating

Chitsuthipakorn

Thanapornpoonpong

2021

Processes

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“…The effects of different RF heating temperatures on the fissure percentage of brown rice with different fissure degrees are shown in Table 3 . The fissure percentage was classified into four groups, namely None (0 fissure), Few (1–2 fissures), Moderate (3–4 fissures), and Severe (≥5 fissures), as reported by [ 31 ]. The morphology of fissures in white rice with different fissure degrees is shown in Figure 4 .…”

Section: Resultsmentioning

confidence: 99%

“…The “None” fissure degree considered the most important characteristic, while the “Severe”, “Moderate”, and “Few” fissure degrees considered the most undesirable characteristic, respectively, because fewer fissure kernels would result in a high head rice yield of milled rice. This result showed that RF heating significantly affected the fissure percentage due to the high absorption of RF energy inside the rice kernels [ 31 ] and that the temperature of the rice grain plays an important role in the development of a heat and moisture gradient inside the grain, resulting in surface hardening [ 32 ] and differential stress [ 33 ], respectively. The optimum condition for RF heating temperature was HA/RF42, as no “Moderate” and “Severe” fissure degrees were observed.…”

Section: Resultsmentioning

confidence: 99%

Effect of Large-Scale Paddy Rice Drying Process Using Hot Air Combined with Radio Frequency Heating on Milling and Cooking Qualities of Milled Rice

Chitsuthipakorn

Thanapornpoonpong

2022

Foods

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The objectives of the study on a continuous flow hot air dryer combined with radio frequency heating at different temperatures (HA/RF) (38 °C, 42 °C, 46 °C, and 50 °C) in a large-scale process compared with conventional continuous flow hot air drying (HA) were (1) to investigate the drying characteristics, drying kinetics, and milling quality of the process and (2) to observe the cooking quality and compare the sensory differences of the cooked rice after treatment. The drying characteristics and moisture diffusivity showed that the higher the radio frequency (RF) heating temperature, the shorter the drying time. The specific energy consumption and energy cost decreased when the RF heating temperature increased. The optimal condition in terms of fissure percentage was HA/RF42. In addition, there were no significant differences in head rice yield and white rice color determination, amylose content, texture profiles, and pasting properties in all HA/RF treatments. In the triangle test, it was found that at least 6% of the population could perceive a difference between HA and HA/RF50. In conclusion, this study proposes the further development of the HA/RF drying process at low-temperature profiles and shows the great potential of RF technology for commercial drying in rice industry.

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A comparative evaluation of nutritional characteristics, physical properties, and volatile profiles of sweet corn subjected to different drying methods

et al. 2021

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Background and objectives Fresh sweet corn is vulnerable to microbial damage and difficult to preservation at ambient temperature due to the high water and sugar contents. Therefore, in the present study, fresh sweet corn kernels were subjected to hot air drying (HAD), vacuum freeze drying (VFD), microwave drying (MD), and short‐ and medium‐wave infrared drying (SMIRD). Findings Different drying ways of dehydrated sweet corns were compared in terms of physical properties, nutritional components, volatile compounds, and antioxidant capacity. After thermal treatment, sweet corn will form more volatile components and increase the flavor of sweet corn, while sweet corn treated by VFD will lose a lot of volatile components and weaken the flavor. Conclusions The results demonstrated that VFD products exhibited higher rehydration capacity, more nutrient retention, and better antioxidant capacity with fewer volatile compounds. A total of 63 different volatile compounds were detected in dried sweet corns. The variety of volatile substances was the maximum in the SMIRD (55), followed by HAD (35), MD (28), fresh (22), and VFD (9). Significanceand novelty Overall, this study would be fundamental for selecting more applicable drying methods to obtain desirable quality of dried sweet corn.

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Continuous microwave drying of germinated brown rice: Effects of drying conditions on fissure and color, and modeling of moisture content and stress inside kernel

Cited by 34 publications

References 52 publications

Quality of Milled Rice from Large-Scale Dried Paddy Rice by Hot Air Combined with Radio Frequency Heating

Quality of Milled Rice from Large-Scale Dried Paddy Rice by Hot Air Combined with Radio Frequency Heating

Effect of Large-Scale Paddy Rice Drying Process Using Hot Air Combined with Radio Frequency Heating on Milling and Cooking Qualities of Milled Rice

A comparative evaluation of nutritional characteristics, physical properties, and volatile profiles of sweet corn subjected to different drying methods

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