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The objective of this study was to investigate the processing parameters and quality of carrots under sequential infrared (IR) dry-blanching and (1) hot air drying (IRB-HAD), (2) infrared drying (IRB-IRD), and (3) Infrared-hot air drying (IRB-IRHAD). Water blanching at 90oC was used for comparison. The quality of dried carrot was evaluated based on vitamin C content, rehydration ratio, color, shrinkage and hardness. Applying IR dry-blanching for 15 min resulted in the reductions of about one log in peroxidase (POD) activities and 54 % in moisture reduction. A notable change in the surface color and retention of vitamin C were obtained with IR blanching. IRB-IRD and IRB-IRHAD had higher drying rates and higher quality. The recommended processing parameters for IRB-IRHAD are IR blanching for 15 min, followed by IR drying to a moisture content of 30–40 % wet basis (w.b.), and then finished by HA drying to a targeted MC (8 % w.b.). [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]

Abstract: Infrared heating was recently used to develop a more efficient roasting technology than traditional hot air roasting. Therefore, in this study, we evaluated the shelf-life of almonds roasted with three different approaches, namely infrared (IR), sequential infrared and hot air (SIRHA) and regular hot air (HA). Nine medium roasted almond samples produced by the aforementioned heating methods were processed at three different temperatures (130, 140 and 150°C), packed in paper bags and then stored at 37°C for three, six or eight months. Shelf-life of the roasted almonds was determined by measuring the changes in colour, peroxide value, moisture content, water activity, volatile components and sensory quality. No significant difference was observed in moisture content and water activity among the almond samples processed with different roasting methods and stored under the same conditions. GC/MS analysis showed that aldehydes, alcohols, and pyrazines were the main volatile components of almonds. Aliphatic aldehydes such as hexanal, (E)-2-octenal, and nonanal were produced as off-odours during storage. Although the overall quality of roasted almonds produced with SIRHA and HA heating was similar during the first three months of storage, their peroxide value and concentration of aliphatic aldehydes differed significantly for different roasting methods and increased significantly in all roasted samples during storage. We postulate that hexanal and nonanal might be better indicators of the shelf life of roasted almonds than the current standard, peroxide value. [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 three processing parameters, e.g. product surface temperature, slice thickness and processing time, on blanching and dehydration characteristics of apple slices exposed to simultaneous infrared dry-blanching and dehydration (SIRDBD) with intermittent heating. A three-factor factorial experiment design was conducted to determine the influence of processing parameters on product temperature, moisture reduction, drying rate, residual polyphenol oxidase (PPO) and peroxidase (POD) activities and surface color change. Slice thickness had a significant effect on product quality and processing characteristics, as faster inactivation of enzymes and quicker moisture reduction took place in thinner slices. A Page model performed well for describing drying behavior during the treatment, and first-order kinetics and a biphasic model fit well for PPO and POD inactivation, respectively. Surface color changes (ΔE) of apple slices during prolonged heating resulted from non-enzymatic browning with an increase in b value was observed. In order to achieve a 1 log reduction in POD activity, the process resulted in a reduction in moisture from 20% to 59% and in ΔE from 2.27 to 5.59. It is suggested that SIRDBD with intermittent heating could be used as an alternative to manufacture high quality blanched and partially dehydrated fruits and vegetables. [Copyright &y& Elsevier]

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: 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 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]

Abstract: The use of infrared (IR) heating for improving the microbial safety and processing efficiency of dry-roasted almonds was investigated. Almonds were roasted at 130, 140 and 150°C with three different methods: IR roasting, sequential infrared and hot air (SIRHA) roasting, and traditional hot air (HA) roasting. The heating rate and pasteurization efficacy of almonds under different roasting methods and temperatures were evaluated. Pediococcus sp. NRRL B-2354 was used as a surrogate for Salmonella enterica Enteriditis PT 30 for evaluating the pasteurization efficacy of different processing methods and conditions. When SIRHA roasting at 130, 140 and 150°C roasting temperatures was used to produce medium roasted almonds, 4.10-, 5.82- and 6.96-log, bacterial reductions were achieved with 38%, 39% and 62% time saving compared to HA roasting at each temperatures, respectively. The decimal reduction time of the bacteria at all roasting temperatures were calculated for SIRHA roasting as 8.68, 3.72 and 1.42min, respectively, with a correlation coefficient greater than 0.92 and the thermal resistance constant was found as 25.4°C. The total color change followed zero-order reaction kinetics and the activation energies were 73.58, 52.15 and 67.60kJ/mol for HA, IR and SIRHA roasting, respectively. No significant difference (p >0.05) was observed in sensory quality of medium roasted almonds processed with different roasting methods. We conclude that the SIRHA roasting is a promising new method for the production of dry-roasted pasteurized almonds. [ABSTRACT FROM AUTHOR]

This study investigated the effect of thickness (0.6, 0.8, 1.0 and 1.3 mm) on non-fried potato chips that were treated with a sequential infrared (IR) radiation blanching and drying method. The process characteristics such as the residual polyphenol oxidase (PPO) activity, moisture content reduction and drying rate of IR-treated potato slices were studied. The quality characteristics, including color and texture, were also determined. The residual PPO activity decreased with the increase in sample thickness, in a range of 2.13–8.81% after IR-blanching. The first-order kinetics fitted well for the PPO inactivation curve. The final moisture content (MC) of samples with various thicknesses reached a range of 3.85–4.51% (w.b.) after IR-treatment. The thinner sample had a faster drying rate than the thicker slices. The drying behavior can be described well using the Midilli model. Surface color changes of potato chips with different thickness were expressed by a 0.12-fold decrease in the L * value, and a 4.72-fold and 0.57-fold increase in the a* and b* values, respectively, after IR-treatment. The values of hardness increased by 0.96-fold with the increase in sample thickness from 0.6 to 1.3 mm. In addition, the sensory evaluation revealed that consumers preferred the sample with a thickness of 0.8 mm based on the overall degree of liking. [ABSTRACT FROM AUTHOR]

This study was aimed to develop a sequential infrared and hot air (SIRHA) drying method for whole almonds and evaluate its effectiveness on decontamination of almonds. Wet almonds with hull and shell were dried using different time-combinations of infrared (IR) radiation and hot air (HA) to determine the optimum drying conditions. Almonds were inoculated with Enterococcus faecium, a surrogate for Salmonella enterica. The SIRHA drying (1h IR at 70 °C and 2h HA) reduced the moisture content of almonds to 7% in 3 h, with a saving of 2 h (40%) of drying time compared with HA drying alone. The population sizes of E. faecium showed the largest size reductions of 4.69 ± 0.71, 1.82 ± 0.39, 1.52 ± 0.31 log CFU/nut on hulls, shells and kernels, respectively, after SIRHA drying combined with tempering (T) (2h IR with 2h T and 1h HA). The peroxide value and free fatty acids content of almond oil samples from all drying treatments were within accepted level for the almond industry. [ABSTRACT FROM AUTHOR]

This study evaluated the use of Infrared (IR) and microwave (MW) dry blanching technology as an alternative to the conventional hot water (HW) blanching of Irish potato slices. Product quality, cell integrity, and Peroxidase (POD) inactivation kinetics were investigated. Also, the POD inactivation kinetics curve was fitted with both mathematical models and artificial neural networks (ANNs). The result showed that MW blanching technique had the shortest POD inactivation time (5 and 7 mins), when compared with HW blanching (7 and 9 mins) and IR blanching (18 and 21 mins). IR blanched samples had the lowest colour change, slowest moisture loss, and lower microbial activity when compared with HW and MW blanching, although the level of vitamin C retention was similar with MW blanched samples. Furthermore, MW blanching had lower electrolyte leakage and microstructure damage, and better texture, when compared with HW and IR blanching. ANNs (R2 = 1.000, RMSE = 1.1597e-14, and SSE = 2.8994e-15) outperformed Weibull distribution (R2 = 0.9914, RMSE = 0.0348, and SSE = 0.0073) in fitting the POD inactivation curve. In conclusion, IR and MW technology were efficient in dry blanching of Irish potato, and ANNs allows for smart industrial control and monitoring of dry blanching equipments, since it can combine multiple process variables. • ANNs had better fitting of the enzyme inactivation kinetic than mathematical models. • IR blanching better preserved the Irish potato microstructure than MW and HW. • MW blanching had moderate electrolyte leakage and better texture than IR and HW. • Thinner slice thickness had faster POD inactivation for all blanching methods. • IR samples had lower surface change and microbial load than MW and HW. [ABSTRACT FROM AUTHOR]

[Display omitted] • Effect of HA and SIRHA drying on CBD and terpene retentions in hemp was studied. • Drying efficiency of the hemp was significantly improved by HA and SIRHA drying. • CBD yield and decarboxylation rate were significantly affected by drying conditions. • Terpene content and profile in hemp changed with the drying conditions. • Drying conditions should be selected tailored to quality requirements of products. This study aimed to investigate the drying effects on the retention of cannabidiol and terpenes in the industrial hemp (Cannabis sativa L.). Hemp inflorescence and leaves from Pipeline, Maverick and Queen-Dream-CBD varieties were dried with hot air (40, 50, 60, 70, 90 °C), and sequential infrared and hot air drying (infrared preheating for 1 and 2 min, then hot air drying at 40 and 60 °C). Ambient air drying and freeze drying were conducted as control groups. As the drying temperature increased from ambient to 90 °C, drying time reduced from 1800 to 210 min, cannabidiolic-acid conversion increased from 0.2%–14.1%, and total terpene retention decreased from 82.1%–29.9%. The total cannabidiol retention (ranging from 83.8%–98.6%) was affected by the drying methods and conditions. The findings suggested that drying conditions should be tailored to the requirements of the final products, which provides important information to the industry for improving the postharvest drying, downstream processing and product development. [ABSTRACT FROM AUTHOR]