The experiments of contact ultrasound-assisted far-infrared radiation (FIR) drying on potato slices were conducted to investigate the effects of ultrasonic power on drying characteristics and quality ...properties. The results showed that contact ultrasound was helpful for accelerating mass transfer of the samples, and the improvement of ultrasonic power could significantly shorten drying time. The ultrasonic reinforcement effect on drying rate declined along with the decrease in moisture content.
D
eff
values were within 1.15 × 10
−10
and 1.96 × 10
−10
m
2
/s, and improved with an increase in ultrasound power. Compared with FIR dried ones, more and larger pore size of microcapillaries in the samples’ tissue structure could be observed with contact ultrasound application, and higher ultrasonic power produced more microtunnels. Contact ultrasound in FIR drying could reduce the color difference of dried potato slices, and decrease the hardness and brittleness values. Higher TPC and TFC could be achieved as ultrasonic power increased.
Far-infrared radiation (FIR) drying is an advanced technique that has recently been applied in food processing. In order to reveal the effects of FIR temperature on dehydration process and quality ...characteristics of kiwifruit slices, FIR drying experiments on kiwifruit slices were conducted. Low-field nuclear magnetic resonance, scanning electron microscopy, colorimeter and chemical analysis were applied to explore the dynamic water states, microstructure, color changes and nutritional components of kiwifruit slices at different FIR temperatures. The results showed that drying time reduced by 57.9% and average drying rate increased by 137.5% as FIR temperature increased from 120 to 280 °C. The water mobility and distribution in kiwifruits changed with the extension of drying time, and increasing FIR temperature could accelerate the migration and removal of moisture. Higher FIR temperature could produce more cavities and larger channels in dried samples. An increase in FIR temperature decreased
L
*
but increased
a
*
values of dried kiwifruits and affected total phenolic content, total flavonoids content and Vitamin C content. Therefore, FIR drying is a promising method to improve drying rate as well as protect product quality of kiwifruit slices.
The structural and functional properties of physical modified rice flour, including ultrasound treated rice flour (US), microwave treated rice flour (MW) and hydrothermal treated rice flour (HT) were ...investigated with wet-milled rice flour (WF) used as a positive control. The results showed the presence of small dents and pores on the rice flour granules of US and MW while more fragments and cracks were showed in HT. XRD and FTIR revealed that moderate ultrasonic treatment promoted the orderly arrangement of starch while hydrothermal treatment destroyed the crystalline structure of rice flour. In addition, the significant decrease of gelatinization enthalpy and the narrowing gelatinization temperature were observed in US. Compared to that of SF, adding physical modified rice flour led to a batter with higher viscoelasticity and lower tan δ. However, the batter added HT exhibited highest G' and G″ values and lowest tan δ, which led to a harder texture of bread. Texture analysis demonstrated that physical modified rice flour (except HT) reduced the hardness, cohesion, and gumminess of rice bread. Especially, the specific volume of bread with US increased by 15.6% and the hardness decreased by 17.6%. This study suggested that ultrasound treatment of rice flour could improve texture properties and appearance of rice bread.
Summary
The effects of red lentil protein with ultrasound‐assisted enzymatic treatment on the quality of brown rice noodles were investigated. The thermostability and anti‐retrogradation ability of ...brown rice flour decreased significantly (P < 0.05), while the elastic and viscous modulus increased after adding untreated red lentil protein. Meanwhile, the cooking loss rate of brown rice noodles increased from 4.41% to 5.68%. When the red lentil protein was treated with ultrasound and enzyme, the protein–starch interaction was enhanced, and the negative effects of protein on brown rice flour and noodles were weakened. Moreover, the rice noodles with ultrasound‐assisted enzyme‐treated red lentil protein showed a lower starch digestibility than brown rice noodles, and its protein digestibility was significantly higher than that of rice noodles with ultrasound or enzyme‐treated protein. Therefore, the addition of ultrasound‐assisted enzyme‐treated red lentil protein could effectively decrease predicted glycaemic index value, improve nutritional value and produce high‐quality brown rice noodles.
The ultrasound‐assisted enzymatic treatment can improve the in vitro protein digestibility, and the addition of treated red lentil protein can efficiently reduce the in vitro starch digestibility of brown rice noodles.
Summary
To explore the effects of wet milling method on highland barley flour and highland barley bread, we investigated the characteristics of highland barley flours and the quality of highland ...barley breads made from whole grain highland barley flour (WGBF), dry‐milled highland barley flour (DBF) and wet‐milled highland barley flour (WBF). Compared to other highland barley flours, WBF had lower damaged starch content (1.37 g/100 g), higher pasting temperature and higher gel strength. In addition, WBF with large particles exhibited low hydration performance. These properties induced a large specific volume (2.62 mL g−1) and good crumb structure of bread with WBF. However, due to the negative effects of damaged starch and insoluble dietary fibre in WGBF and DBF, the specific volumes of bread with WGBF and DBF (1.30 and 1.70 mL g−1) were lower than the bread with WBF. The results showed that WBF with high starch granules integrity could produce preferable highland barley bread.
Graphical representation of the preparation steps of highland barley flour and bread.
The rice quality and starch functional properties, as well as the storability of three YY-IJHR cultivars, which included YY12 (biased japonica type YY-IJHR), YY1540 (intermedius type YY-IJHR) and ...YY15 (biased indica type YY-IJHR), were studied and compared to N84 (conventional japonica rice). The study results suggested that the three YY-IJHR varieties all had greater cooking and eating quality than N84, as they had lower amylose and protein content. The starch of YY-IJHR has a higher pasting viscosity and digestibility, and there was a significant difference among the three YY-IJHR cultivars. Rice aroma components were revealed by GC-IMS, which indicated that the content of alcohols vola-tile components of YY-IJHR were generally lower, whereas the content of some aldehydes and esters were higher than N84. In addition, YY-IJHR cultivars’ FFA and MDA contents were lower, which demonstrated that YY-IJHR had a higher palatability and storability than those of N84 in fresh rice and rice stored for 12 months. In conclusion, this study suggested that YY-IJHR had better rice quality and storability than N84. PCA indicated that the grain quality and storability of YY12 and YY15 were similar and performed better than YY1540, while the aroma components and starch functional properties of YY-IJHR cultivars all had significant differences.
The purpose of this study was to compare the gelatinization and retrogradation properties of highland barley starch (HBS) using different extraction methods. We obtained HBS by three methods, ...including alkali extraction (A-HBS), ultrasound extraction (U-HBS) and enzyme extraction (E-HBS). An investigation was carried out using a rapid viscosity analyzer (RVA), texture profile analysis (TPA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and Fourier-transform infrared spectrometry (FTIR). It is shown that the different extraction methods did not change the crystalline type of HBS. E-HBS had the lowest damaged starch content and highest relative crystallinity value (p < 0.05). Meanwhile, A-HBS had the highest peak viscosity, indicating the best water absorption (p < 0.05). Moreover, E-HBS had not only higher G′ and G″ values, but also the highest gel hardness value, reflecting its strong gel structure (p < 0.05). These results confirmed that E-HBS provided better pasting stability and rheological properties, while U-HBS provides benefits of reducing starch retrogradation.
In order to explore the reinforcement effect of contact ultrasound on hot air drying (HAD), the effects of different ultrasonic powers and drying temperatures on drying characteristics and quality of ...pear slices were studied. The results showed that the increase in ultrasonic power and drying temperature could significantly shorten drying time. The drying process of pear was internal diffusion control, and ultrasound application could reduce internal diffusion resistance as well as improve dehydration rates. SEM results illustrated that ultrasound’s cavitation and mechanical effects could produce more microchannels and dilate intercellular spaces in pear slices. DSC results revealed that ultrasound application during drying could improve water mobility and then reduce glass transition temperature. Both drying temperature and ultrasonic power had significant effects on total phenolic, total flavonoids, VC, and rehydration ratio, and contact ultrasound application in HAD was beneficial to increasing the nutrient component contents.
Practical applications
Hot air drying (HAD) is a traditional and frequently used drying method. Yet it has the defects of low thermal efficiency, lengthy time, and unacceptable product quality. Nowadays, the application of contact ultrasound strengthening technology has drawn great attention in drying enhancement. When contact ultrasound is applied in HAD of pear, ultrasonic energy is directly transmitted into materials without passing through any medium, so as to enhance the utilization and enhancement effect of the ultrasound. The ultrasound application could enlarge and even produce more microchannels in pear slices, which could accelerate moisture migration. Contact ultrasound application in drying process was beneficial to improving the drying rate as well as increasing nutrient components. Therefore, contact ultrasound‐strengthened HAD technology is promising and could be applied for drying agricultural products.
In order to investigate the feasibility and the enhancing effect of contact ultrasound application during far-infrared radiation (FIR) drying, a contact ultrasound strengthened FIR (CUFIR) drying ...equipment was fabricated and used, and CUFIR drying experiments on pear slices were carried out to explore the synergetic effects of ultrasound power and FIR heating on drying characteristics, microstructure, and quality of dried pear products. The results show that the application of contact ultrasound could be obviously helpful to accelerate internal mass transfer in pear slices and improve the drying rate of FIR drying, and higher ultrasound power could lead to stronger strengthening effect. The enforcing effect of ultrasound increased at higher FIR power, and weakened with the reduction of moisture content during CUFIR drying. The D
eff
values ranged from 4.76 × 10
−10
m
2
/s to 13.94 × 10
−10
m
2
/s in this study and the increase of both FIR power and ultrasound power had significant and positive influence on the increasing of D
eff
values. With scanning electrical microscope (SEM), it was observed that the improvement of ultrasound power could enlarge the size of microcapillaries and even generate new micropores and microchannels on the ultrasound-treated surface and in the organism structure of pear slices. The increase of ultrasound power could improve total phenolic content (TPC) and total flavonoids content (TFC) of pear slices at FIR powers of 100 and 220 W. Yet, the application of contact ultrasound with ultrasound power of 60 W had negative influence on TPC and TFC at FIR power of 340 W. Although the ascorbic acid content (AAC) reduced as FIR powers increased during FIR drying without contact ultrasound assistance, the increase of ultrasound power could improve AAC at all FIR powers. The CUFIR drying at ultrasound power of 60 W and FIR power of 220 W achieved the lowest energy consumption. Therefore, the application of FIR drying combined with contact ultrasound is a promising method to improve drying rate as well as protect product quality.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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