Search

The objective of this work was to determine the effects of infrared radiation combined with heating on grape seeds and oil quality. Experimental results showed that high moisture removal was achieved through infrared radiation heating. After infrared radiation heating for 108 s, the inactivation rates of total aerobic bacterial and total mold-yeast counts of the grape seeds were 1.97 ± 0.12 and 0.62 ± 0.09 log CFU/g, respectively. The maximum microbial reduction was achieved after infrared radiation heating of the grape seeds to 135 ℃ and subsequent holding at 75 ℃ for 60 min. The crude oil yield of samples subjected to these conditions was 10.39%, which was significantly higher (p < 0.05) than that of the control sample, and their final moisture content was 7.20%. Additionally, increases in the free fatty acid content and peroxide value of the oil were achieved. The iodine value of the oil decreased. In conclusion, surface pasteurization with a high oil yield could be achieved by the combination of infrared radiation heating and the holding process. Consequently, infrared radiation treatment is suggested to be a promising method for the surface pasteurization of grape seeds. [ABSTRACT FROM AUTHOR]

Abstract: This study investigated the effects of blanching and dehydrating using infrared (IR) radiation on the oil content of fried potato chips. The quality characteristics such as color and texture of IR‐treated potato chips were also investigated. Following the blanching, the potato slices were subjected to IR‐dehydrating with a series of duration times prior to deep‐fat frying. It was observed that the complete inactivation of polyphenol oxidase enzyme could be finished in 180 s of IR‐blanching. The sample with a longer dehydrating time was detected to contain the lower moisture content, which corresponded to a shorter frying time during frying and the lower oil content of the final product. It was demonstrated that the total oil content of IR‐treated samples reduced 13.79% at least compared to the conventional method. The b* values for IR‐treated potato chips generated faster during frying, which showed the significant changes (p < .05) compared to water‐treated samples. In addition, the sensory evaluation revealed that the consumers would more prefer the sample with 120 s of IR‐treated chips which showed a desirable taste. Practical applications: In this study, we would like to consider some topics about infrared blanching and dehydrating pretreatment on oil content of fried potato chips. Often, it is precisely that are particularly useful in the actual production. IR‐blanching was able to inactivate the polyphenol oxidase enzyme of potato slice completely. The initial moisture content of slices was demonstrated to play an important role in the quality of chips. Besides, IR pretreatments of potato slices also reduced the process time of deep‐fat frying. The goal of this study is to give suggestions for produce potato chips with lower calorie and oil content. [ABSTRACT FROM AUTHOR]

Infrared radiation heating has a promising potential in improving drying rate and food safety, but its effect on the storage stability of rough rice is not known. The objective of this study was to develop an infrared drying (IRD) method to improve the storage stability of rough rice during storage. The effects of IRD on the physicochemical properties of stored rough rice were compared with those of hot air drying (HAD) and ambient air drying (AAD). Freshly harvested M206 rice was dried to a targeted moisture content of 16 % (d.b.) by using IRD, HAD, and AAD. The dried rice samples were then stored at 35.0 ± 1.0 °C and a relative humidity of 65.0 ± 3.0 % for up to 10 months. The physicochemical and cooking properties of rice samples were periodically determined over the storage duration. Compared with AAD, the yellowness index, water uptake, and volume expansion ratio of the rough rice dried with IRD and stored for 4 months were reduced by 26.3, 76.3, and 14.5 %, respectively. After 10 months of storage, the change in hardness of cooked IR-dried rice was significantly reduced by 22 % compared to that of samples dried with AAD. IRD likely caused a slight denaturation of protein and annealing of starch that was located on the surface layer of rice kernels, resulting in decreased gelatinization temperature, enthalpy, and viscosity, and reduced the changes in microstructure, but retained cooking characteristics after storage. Therefore, IRD is recommended as a promising technique that achieves high rice drying efficiency and improved storage stability. [ABSTRACT FROM AUTHOR]

A pilot scale infrared dry-peeling system for tomatoes was designed and constructed. The system consisted of three major sections including the IR heating, vacuum, and pinch roller sections. The peeling performance of the system was examined under different operational conditions using tomatoes with different cultivars and sizes. Three lines of tomatoes were heated and processed at the same time at a residence time of 125 s and achieved a percentage of fully peeled tomatoes of 85%, a peeling yield of 82%, and an average thickness of peeled tomato skin of 0.75 mm. When tomatoes were loaded as a single line, the required heating time was reduced to a range from 80 to 100 s, depending of tomato size, for achieving the same level of peeling percentage and yield. The presence of the vacuum section could achieve cracks in 100% of the tomatoes after IR heating. The peeled products from IR heating had high firmness and appealing surface integrity, which indicated desirable quality characteristics. Because the dry-peeling is a chemical- and water-free process, residuals of tomato skins after IR peeling could be easily utilised as value-added by-products. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the effect of infrared (IR) heating and tempering treatments on storage stability of rough and brown rice. Samples of freshly harvested medium grain rice variety M206 with initial moisture content of 25.03 ± 0.21 % (d.b.) were used. They were dried using IR, hot air at 43 °C, and ambient air for comparison. For IR drying, rice were heated to temperature of 60 °C under radiation intensity of 4685 W/m, followed by 4 h tempering and natural cooling. The dried samples were divided into two portions, which were respectively used as rough and brown rice for storage at 35 ± 1 °C with relative humidity of 65 ± 3 % for 10 months. The drying characteristics and milling quality of rice were determined. Free fatty acid, peroxide value, and iodine value were determined to detect any notable degradation of lipids in rough and brown rice during storage. High heating and drying rates of rice were achieved under IR heating. It took only 58 s to heat rough rice to temperature of 60 °C with a corresponding moisture removal of 2.17 percentage points during IR heating. The total moisture removal after natural cooling reached to 3.37 percentage points without additional energy input. IR drying did not show any adverse effects on milling quality of the dried rice. Additionally, it resulted in an effective inactivation of lipase, and consequent improvement in the long-term storage stability of rough and brown rice was achieved under accelerated storage condition. It is concluded that the improvement in rough and brown rice stability during storage can be achieved through drying rough rice using IR heating to temperature of 60 °C followed by tempering for 4 h and natural cooling. IR drying provides a potential to store brown rice instead of rough rice with extended shelf life and reduced cost. [ABSTRACT FROM AUTHOR]

Abstract: This study investigated the effects of various processing parameters on carrot slices exposed to infrared (IR) radiation heating for achieving simultaneous infrared dry-blanching and dehydration (SIRDBD). The investigated parameters were product surface temperature, slice thickness and processing time. A three-factor factorial design was conducted to determine the influence of processing parameters on moisture reduction, drying rate, residual peroxidase (POD) activities, surface color change and vitamin C retention. High surface temperature and/or thin slices had faster inactivation of enzymes and quicker moisture removal compared to the low surface temperature and/or thick slices. A Middili model performed well for describing drying behavior during the treatment, while a biphasic model and a quantic model fit well for describing the POD inactivation and the surface color change during the process, respectively. The process which produced 1 log reduction in POD activity has resulted in moisture reduction from 40.2 to 88.8 g/100 g, overall color change (ΔE) from 3.17 to 5.13 and retention of vitamin C from 56.92 to 77.34 g/100 g compared to control. It was concluded that SIRDBD could be used as an alternative to produce high quality blanched and partially dehydrated fruits and vegetables. [Copyright &y& Elsevier]

Highlights: [•] The mechanism of peeling tomatoes using infrared heat was investigated. [•] Microstructure images revealed mechanistic differences of infrared, lye, and steam peeling. [•] Layer separation was observed from tomato epidermal tissues treated by infrared. [•] Combined experimental and modeling analyses explained crack behaviors of tomato skin. [•] Promoting rapid and uniform surface heating is essential for infrared peeling. [Copyright &y& Elsevier]

This study investigated the drying and quality characteristics of carrot slices under catalytic infrared ( CIR) and hot air ( HA) heating. Carrot slices with thicknesses of 3, 5 and 7 mm were dried at temperatures of 60, 70 and 80 C with both methods. CIR had higher drying rates, shorter drying times and greater effective diffusivities than HA before the moisture contents reached the range of 16-30% on a wet basis (w.b.). The total drying times required by CIR to reach the final moisture content was 60% less than HA. The effective diffusivities were in the range of 2.38-10.30 × 10−9 m2 s−1 for CIR drying and 1.43-5.50 × 10−9 m2 s−1 for HA drying. Results revealed that carrot slices dried with CIR, particularly at 60 and 70 C, had better rehydration characteristics than the samples dried with HA. Thickness had a significant impact on overall color change of carrot slices. The obtained correlation coefficient ( R2) and root mean square error values indicated that the Midilli model was the best for predicting the moisture ratio change kinetics of carrot slices for both drying processes. Practical Applications These results indicate that CIR drying is an effective method to obtain high-quality products. This paper was to optimize the CIR and HA process of carrot slices. The significance of this research can improve the drying efficiency of CIR in carrot slices. Throughout the trial, the production-scale CIR dryer was used, which means that the CIR process can provide technological support to produce dried carrot slices. In addition, it also provides a reference using sequential CIR drying and HA drying for carrot slices. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the moisture removal characteristics of thin layer rough rice heated by infrared ( IR) and cooled with various cooling methods. Thin layer rough rice samples with different initial moisture contents ( MCs) were heated using a catalytic IR emitter for four exposure times and radiation intensities. High heating rate and moisture removal were achieved during the IR heating period. After heating, more moisture removal was achieved during the cooling period. The achieved grain temperatures ranged from 35.1 to 68.4 C under the tested heating conditions. The vacuum and forced air cooling methods removed more moisture than did the natural cooling. When rice with 25.7% MC was heated by IR, MC was reduced by 3.2, 3.5, and 3.8 percentage points for rice heated to 63.5 C at the IR intensity of 5348 W/m2 for120 s followed by natural cooling for 40 min, forced air cooling for 5 min and vacuum cooling for 10 min, respectively. Practical Applications To design efficient infrared ( IR) dryers for rough rice, it is important to optimize the operating parameters of IR dryer to achieve high heating rate, fast drying and good quality of end-products. To achieve the aforementioned objectives, we have been conducting several studies including our previous publications ( Pan, Khir et al. and this study). The outcomes of our studies have clearly indicated that a high heating rate, fast drying, good quality and simultaneous drying and disinfestation can be achieved by IR heating of rough rice to bout 60 C followed by tempering and natural cooling with tested bed thickness up to 10 mm. Consequently, IR heating followed by cooling could be an effective approach for designing IR rough rice dryers. It is expected that this alternative approach could be used as an energy saving drying method with improved drying efficiency, space saving, clean working environment and superior product quality compared with the conventional heated air drying method. [ABSTRACT FROM AUTHOR]

Abstract: The effectiveness of using infrared (IR) dry-peeling as an alternative process for peeling tomatoes without lye and water was studied. Compared to conventional lye peeling, IR dry-peeling using 30s to 75s heating time resulted in lower peeling loss (8.3%–13.2% vs. 12.9%–15.8%), thinner thickness of peeled-off skin (0.39–0.91mm vs. 0.38–1.06mm), and slightly firmer texture of peeled products (10.30–19.72N vs. 9.42–13.73N) while achieving a similar ease of peeling. IR heating increased the Young's Modulus of tomato peels and reduced the peel adhesiveness, indicating the tomato peels to loosen, become brittle, and crack more easily. Also, IR heating resulted in melting of cuticular membrane, collapse of several cellular layers, and severe degradation of cell wall structures, which in turn caused peel separation. These findings demonstrated the effectiveness of the novel IR dry-peeling process for tomatoes. Industrial relevance: Development of a sustainable and non-chemical peeling technique for food processing industry is urgent. Currently, industrialized peeling methods such as hot lye or steam peeling are water- and energy-intensive operation and result in a large amount of waste effluent. Disposal of these wastewater containing high salinity and organic solids poses negative environmental footprints. Tomato processors have long been interested in pursuing a sustainable and non7 chemical peeling alternative in order to minimize waste effluent containing high salinity and organic loads and reduce the negative environmental impacts associated with conventional hot lye peeling. The emerging infrared dry-peeling technique offers a novel approach to eliminate the usage of chemicals and water in the peeling process while maintaining high quality peeled products. The study explored several crucial and fundamental aspects of developing infrared radiation heating technology as a sustainable tomato peeling method. The findings of this research provide scientific evidence of the benefits of infrared dry-peeling in comparison to the conventional hot lye peeling and have been used for the development of a pilot scale tomato infrared dry-peeling system. [Copyright &y& Elsevier]

Abstract: To design efficient infrared (IR) dryers for rough rice, it is important to understand the drying behavior of rough rice under IR heating. The objective of this study was to determine the moisture diffusivity of rough rice under IR heating followed by cooling. The effects of initial moisture content, rice temperature, drying bed thickness, tempering, and cooling methods on moisture diffusivity and moisture diffusivity coefficient were investigated. Samples of freshly harvested medium grain rice (M202 variety) with initial moisture content (MC) of 25.8, 31.2 and 33.8g moisture/100g dry solid were used. They were dried with IR radiation intensity of 5348W/m2, for six exposure times, 15, 30, 40, 60, 90 and 120 s. The tested drying bed thicknesses were single-layer, 5mm and 10mm. The unsteady diffusion equation based on Fick’s law and slope methods were used to describe moisture diffusivity. The results indicated that rough rice moisture diffusivities under IR heating and cooling were significantly affected by rice temperature and tempering treatment, respectively. High heating rate and moisture diffusivity were achieved with IR heating. It took only 60, 90 and 120 s to achieve about 60°C rice temperature with corresponding moisture diffusivities of 4.8 × 10−9, 3.6 × 10 −9 and 3.4 × 10−9 m2/s during heating for drying bed thicknesses of a single layer, 5mm and 10mm, respectively. The moisture diffusivity coefficients during heating and cooling of IR dried rice with tempering were much higher than those of convective drying, which reflected the high drying rate of the IR drying method. [ABSTRACT FROM AUTHOR]

Abstract: This study investigated the effects of various processing parameters on apple slices exposed to infrared (IR) radiation heating in a continuous heating mode for achieving simultaneous infrared dry-blanching and dehydration (SIRDBD). The investigated parameters were radiation intensity, slice thickness and processing time. A three-factor factorial experiment design was conducted to determine the influence of parameters on the heating and drying rates, product temperature, moisture reduction, residual polyphenol oxidase (PPO) and peroxidase (POD) activities and surface color change (ΔE). High radiation intensity and/or thin slices had faster increase of product temperature, and quicker moisture removal and inactivation of PPO and POD, than did low radiation intensity and/or thick slices. The simple page model performed well for describing drying behavior during SIRDBD. The first-order kinetics and the fractional conversion models fitted well for PPO and POD inactivation curves, respectively. Surface color changes of apple slices were mainly due to the decrease of L value and increase of a value, which corresponded to enzymatic browning occurred during the process. To achieve 1 log reduction of POD, the SIRDBD treatments resulted in moisture reductions of 15.35–49.29% and ΔE between 2.030 and 5.518. It has been concluded that SIRDBD with continuous heating could be used as an alternative to the current processing methods for producing high-quality blanched and partially dehydrated fruits and vegetables. [Copyright &y& Elsevier]

Abstract: The drying and quality characteristics of banana slices processed with a sequential infrared radiation and freeze-drying (SIRFD) method were investigated. Cavendish bananas slices with 5mm thickness were predehydrated using IR heating at each one of three radiation intensities, 3000, 4000, and 5000W/m2 or hot air at 62.8°C. The predehydrated samples with 20% and 40% weight reductions obtained using 4000W/m2 IR intensity were then further dried using freeze-drying for various times to determine the effect of predehydration on the drying rate during freeze-drying. To improve the quality of dried banana chips, the banana slices were also treated with a dipping solution containing 10g/l ascorbic acid and 10g/l citric acid before the IR predehydration. Control samples were produced using regular freeze-drying without the predehydration. The quality characteristics of dried banana chips, including color, thickness shrinkage and crispness, were evaluated. The predehydration results showed that the drying rate of IR heating was significantly higher than the hot air drying and increased with the increase of IR intensity. For example, it took 10 and 38min to achieve 40% weigh reduction by using IR at 4000W/m2 and hot air drying, respectively. However, the banana slices with IR predehydration dried slower during freeze-drying compared to the samples without predehydration, which was due to texture changes that occurred during the predehydration. Acid dipping improved product color and also reduced freeze-drying time compared to non-dipped samples. It has been concluded that SIRFD can be used for producing high crispy banana chips and additional acid dipping improved product color and reduced required freeze-drying time. [Copyright &y& Elsevier]

Abstract: We evaluated the finished product quality and infrared (IR) drying characteristics of fresh and sugar-infused blueberries dried with a catalytic infrared (CIR) dryer. IR drying tests were conducted at four product temperatures (60, 70, 80, and 90°C) to evaluate the drying rate and the color and texture of the finished product. Fresh blueberries dried with convective hot air drying at 60°C were used as control for comparison. The experimental data of moisture changes during IR drying were modeled with eight different models, including Page, modified Page, Thompson, Newton, Wang and Singh, and Henderson and Pabis, and two models developed in this study. The Thompson model showed the best fit to all experimental data. The CIR drying produced firmer-texture products with much reduced drying time compared with hot air drying. For fresh blueberries, CIR drying conserved drying time by 44% at 60°C. The effective moisture diffusivity ranged from 2.24×10−10 to 16.4×10−10 m2/s and from 0.61×10−10 to 3.84×10−10 m2/s for fresh and sugar-infused blueberries, respectively. [Copyright &y& Elsevier]

Abstract: The objective of this study was to investigate the drying characteristics, milling quality, and effectiveness of disinfestation of rough rice under conditions of infrared (IR) radiation heating. Freshly harvested medium grain rice (M202) samples with low (20.6%) and high (25.0%) moisture contents (MCs) were used for this study. Single-layer rough rice samples [non-infested and infested with the adults and eggs of lesser grain borers (Rhizopertha dominica) and angoumois grain moths (Sitotroga cerealella)] were heated for various durations using a catalytic IR emitter. The effects of the tempering treatment and natural and forced air cooling methods on moisture removal, milling quality and disinfestation were determined. A high heating rate and corresponding high moisture removal were achieved by using IR heating. After heating, tempering increased moisture removal during cooling and improved the milling quality of the rice samples. When 20.6% MC rice was heated by IR for 60s, the results were a rice temperature of 61.2°C, 1.7% MC removal during the heating period, and an additional 1.4% MC removal after tempering and natural cooling. In addition, the rice had 1.9% points higher head rice yield than a control sample dried with room air. The heating and tempering treatment also completely killed the tested insects. We concluded that simultaneous drying and disinfestation with high rice milling quality can be achieved by using a catalytic IR emitter to heat rough rice to 60°C, followed by tempering and slow cooling. [Copyright &y& Elsevier]

The aim of this study was to improve storage characteristics of brown rice by using infrared radiation drying (IRD) through comparison with hot air drying (HAD) and ambient air drying (AAD). After heating by IR from 20 °C to 60 °C within 58 s, 2.17 percentage points moisture of rough rice (initial moisture content is 25.0 ± 0.2% in dry basis) were removed without adverse effect on germination capacity of husked brown rice. Compared with AAD, IRD slowed down the increase in yellowness, water uptake and volume expansion ratio of brown rice by 47.9%, 41.0% and 37.9% after four months of storage, and decreased the temperature range and enthalpy of gelatinization, the peak and breakdown viscosities. These changes might due to the higher stabilization effect of IRD on the microstructure and thermal properties of proteins and starch granules than AAD. IRD is an effective method to improve storage stability of brown rice. [ABSTRACT FROM AUTHOR]

The objective of this study was to develop a new rice drying method using IR heating followed by tempering. Freshly harvested medium grain rice (M206) samples with different initial moisture contents (IMCs) were used in this study. The samples were dried for one- and two-passes using a catalytic IR emitter to reach rice surface temperature of 60 °C. After IR heating, the samples were tempered in an incubator at 60 °C for different durations ranging from 1 to 5 h. The effects of new drying method on moisture removal, milling quality, and shelf life of rice bran were evaluated. High heating and drying rates and good milling quality of rough rice were achieved. It took only 55 s to heat the rice samples to 60 °C. For one-pass drying and 4 h tempering treatment, the total moisture removals were 3.33, 3.78 and 5.89 g moisture/100 g dry solid for samples with initial moisture contents of 20.06, 25.53 and 32.50 g moisture/100 g dry solid, respectively. IR heating did not generate adverse effects on milling quality of rough rice. Importantly, the storage stability of rice bran from the new drying method was extended to 38 days compared 7 days from current drying practice. [ABSTRACT FROM AUTHOR]

This paper investigated the effect of catalytic infrared radiation (CIR) only and CIR coupled with holding time (CIRH) on decontamination of damp-returning dried shiitake mushrooms contaminated with Aspergillus niger (A. niger). The effect of initial moisture content (IMC) of the samples on CIR/CIRH operation layout was also investigated. Analysis of surface color, observations of electron microscopy and evaluation of quality (retention rate of total sugar, crude protein and total phenolics) directly manifested that CIRH treatment had the outstanding potential to maintain the original appearance and microstructure compared to CIR (p < 0.05). Meanwhile, the envisaged model (Log-Linear + tail) achieved expected results for the inactivation of A. niger with R 2 = 0.9790–0.9977, which can well predict the changes in A. niger of dried shiitake mushrooms with different IMCs in the holding process. Therefore, the present work could pave the way for future production of good quality dried shiitake mushrooms using CIRH. • CIRH can effectively reduce Aspergillus niger on dried shiitake mushrooms. • CIRH worked better for samples with high initial moisture content. • CIRH can effectively maintain the original appearance and microstructure. • Inactivation kinetic of Aspergillus niger conformed to Log-Linear + tail model. [ABSTRACT FROM AUTHOR]

Infrared (IR) radiation heating has a promising potential to be used as a sustainable and effective method to eliminate the use of water and chemicals in the jujube-peeling process and enhance the quality of peeled products. The objective of this study was to investigate the feasibility of using IR heating as a dry-peeling method for jujube. The rotating Li jujube fruits were heated using two electric IR emitters. The effects of IR radiation intensity (5.25–6.07 W/cm 2 ), emitter distance (75–85 mm), and heating time (40–60 s) on the peeling performance of jujube were investigated. Lye-peeled jujubes were used as a control. The operating parameters of the IR peeling system were optimized using response surface methodology (RSM). The heating with an IR intensity of 5.25 W/cm 2 at the emitter distance of 75 mm for 56 s were found as the optimum operating conditions resulting in the peelability of 96%, peeling easiness of 3.8 and moisture loss of 1.29% at jujube surface temperature of 115 °C. The experimental results agreed well with those predicted by the models. The IR peeled jujube had significantly low peeling loss and color change compared to lye peeled ones. [ABSTRACT FROM AUTHOR]

Highlights: [•] Dynamic mechanical analysis characterized the viscoelastic changes in tomato skins. [•] Dynamic moduli of infrared heated peels differed from those of lye heated samples. [•] Viscoelastic behaviors reflected mechanistic difference between lye and infrared peeling. [•] Shifts in transition temperature after peeling indicated structural changes in biopolymers. [ABSTRACT FROM AUTHOR]

Abstract: Salinity and wastewater disposal problems associated with the conventional wet-lye method for peeling clingstone peaches result in considerable negative environment impacts. The efficacy of using infrared (IR) heating as an alternative method for peach peel removal was investigated to eliminate the use of water and chemicals. Peaches sorted into three size categories were double-sided heated under IR with three emitter gaps for a range of heating times from 90 s to 180 s. Wet-lye peeling was used as a control. Results showed that 180 s IR heating for medium sized peaches under an emitter gap of 90 mm yielded 84 mm2/100 mm2 peelability and 90 g/100 g peeling yield, produced peeled products with comparable firmness and color to wet-lye peeled peaches. Surface temperature increased rapidly (> 00 °C) during IR heating whereas the flesh temperature at 16 mm beneath skin remained relatively low (<45 °C). Thermal expansion of cell walls and collapse of cellular layers adjacent to skins were found in IR heated peaches and differed from the micro-structural changes observed in lye heated samples, indicating their mechanistic difference. Promoting uniform and rapid surface heating is essential to further develop IR heating as a non-chemical method for peach peeling. [Copyright &y& Elsevier]

The use of low power-short time microwave (MW) treatment before infrared (IR) heating could help improve the peeling performance of beetroot. MW-assisted IR peeling (MWIR) and IR peeling of beetroot were investigated and compared with the conventional hot-lye peeling method. Also, the effects of these peeling methods on the quality and microstructure were evaluated. Hot-lye peeling at 95 °C for 40 s and 60 s was used as control. Results showed that MW-assisted IR peeling at power 640 W and heating time 7 min produced samples with the highest peelability (99.4%), lowest peel thickness (0.075 mm), and peel remaining (0.8%), lower peeling loss (4.23 g), and better peeling easiness when compared with lye peeling and IR peeling. IR peeling alone produced samples with the lowest peeling loss (2.87 g) and surface colour change, and the highest vitamin C retention (75.32%) than MW-assisted IR and lye peeling respectively. The product microstructure for the different peeling methods showed cellular distortion as a result of thermal expansion. MW pretreatment shows a promising potential to further develop the IR dry-peeling method, to replace the conventional hot lye chemical peeling. • MW-assisted IR heating produced beetroot with better peeling performance. • Addition of MW technology in the peeling treatments increased the cellular damage. • IR peeling better preserved the surface colour change and vitamin C degradation. • Longer IR heating time was observed to have a positive effect on the peelability. • MW and IR technologies completely replace conventional hot-lye peeling of beetroots [ABSTRACT FROM AUTHOR]

A new drying technology, far-infrared radiation heating assisted pulsed vacuum drying (FIR-PVD) was applied to process blueberries. Influences of drying temperature, vacuum pressure duration (VPD), and ambient pressure duration (APD) on drying characteristics and quality attributes of blueberries were investigated under FIR-PVD. Results showed that drying temperature, APD, and VPD had significant influence on drying time and quality attributes of dried blueberries expect for color and cohesiveness. Compared to hot air dried blueberries, FIR-PVD seriously damaged the cellular walls of blueberries during drying at 65 °C. The highest total phenolics (TP) and total monomeric anthocyanins (TMA) contents of dried blueberries were obtained at 65 °C with pulsed ratio of 15 min: 4 min and 15 min: 2 min, respectively. The FIR-PVD products obtained lower color difference, better mechanical properties and rehydration performance and maintained higher antioxidant capacity by shortening drying time, reducing exposure to oxygen, and modifying the microstructure compared to hot air drying. Blueberry is a popular function fruit around the world. With high moisture content and tender tissue, fresh blueberry is very susceptible to microbial infection even under low temperature storage conditions. Drying is a good alternative to extend the shelf life and increase the availability of fresh blueberries. However, the existence of waxy hydrophobic layer covered the surface of blueberries inhibits moisture diffusion during drying. Chemical dipping and thermal blanching pretreatments were usually used to reduce the influence of skin hydrophobicity and promote moisture diffusion. Nevertheless, the chemical additive residue leads to food safety risk and it's a big challenge to deal with the corrosive waste chemical solutions, while thermal blanching resulted a high loss of bioactive compounds. FIR-PVD is a recent developed emerging drying technology to process berries with waxy layer beyond pretreatments. Results indicated that FIR-PVD is a very promising technology for processing blueberries with the improvement of drying efficiency and quality attributes. [Display omitted] • FIR-PVD promoted drying process and preserved blueberry quality. • FIR-PVD seriously damaged the cellular walls of blueberries. • FIR-PVD samples maintained higher antioxidant capacity. • More porous microstructures were observed in FIR-PVD products. • FIR-PVD products showed better mechanical properties and rehydration performance. [ABSTRACT FROM AUTHOR]

Infrared radiation (IR) heating could be a potential alternative peeling method to address the long-term water supply and wastewater disposal issues involved in the conventional lye peeling process of pears. The objective of this study was to investigate the feasibility of IR peeling technology as an environmentally friendly alternative practice to efficiently produce peeled pear products with superior quality and yield. A pilot IR Dry-Peeling System consisting of catalytic IR emitters, roller conveyor, and peeler remover was developed and used for this research. Effects of the pear firmness and heating time on the peeling performance and product quality were studied. Under the continuous loading condition, the most desirable peeling result was achieved for Bartlett pears in the initial firmness range of 22 to 31 N after 99 s of IR heating. The results of IR peeling indicated superior product quality with relative thin cooking ring (0.76 ± 0.20 mm), limited peeling loss (9.25 ± 1.25%), and fairly ease of peeling (5.33 ± 1.00). According to SEM photomicrographs of pericarp cross-section, IR heating caused loss of integrity and compartmentalization of cells of the hypodermal layer to only "ripe" pears (firmness of 26.5 ± 2.8 N). Thermal effect of IR heating dramatically disrupted the middle lamella of hypodermal cells and resulted in mechanical failure of those cells and subsequent layer loosening of "ripe" pears. • Infrared heating achieved the desirable peel removal and product quality without any water use or wastewater generation • Pears in the firmness range of 22 to 31 N yielded the optimal peeling results from infrared heating • Pears at the early maturity stage required extended infrared heating time for peeling • Mechanism of skin loosening of ripe pears under infrared heating was loss of integrity of the hypodermal cells • Cuticle layers of unripe pears formed cracks after infrared heating leading to failure of vapor pressure accumulation [ABSTRACT FROM AUTHOR]