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The ultrasound‐assisted hot air drying characteristics of Phyllanthus emblica was investigated in this paper. The effects of hot air temperature (60°C, 65°C, 70°C, and 75°C), ultrasonic pretreatment time (2, 4, 6, and 8 min), and ultrasonic power (200, 250, 300, and 350 W) on the drying rate, energy consumption, color change, and rehydration rate were evaluated and compared. It was found that the drying rate of Phyllanthus emblica increased with the hot air temperature. The drying time of Phyllanthus emblica with ultrasonic pretreatment was reduced by 10.0%, 25.0%, 21.4%, and 9.0% at 60°C, 65°C, 70°C, and 75°C, respectively. However, the hot air drying was not proportionally promoted by the increase of ultrasonic power or the extension of pretreatment time. Only an appropriate ultrasonic power or pretreatment time can not only improve the drying rate and rehydration rate, but also reduce the energy consumption and the total color change of the dried samples. A new drying model that considered the influences of hot air temperature, pretreatment time, and ultrasonic power was developed to fit the drying process. The results showed that the new model can accurately predict the hot air drying process of Phyllanthus emblica with and without ultrasonic pretreatment. Practical applications: Phyllanthus emblica contains a variety of nutrients and has various biological activities. However, the harvest period and shelf life of Phyllanthus emblica is very short, and the fruit is prone to mildrew and browning after picking, which in turn leads to the loss of its nutritional and economical value. Thus, for the long‐term preservation of Phyllanthus emblica, drying techniques are needed. In the food industry, hot air drying is widely used due to its low cost and easy operation; however, it also has some disadvantages such as long drying time, the oxygen‐rich drying environment. These shortcomings lead to a low quality of dried materials. Ultrasonic pretreatment before hot air drying can improve drying efficiency without adversely affecting the drying quality of the material. In recent years, ultrasonic pretreatment before food drying has become a research hotspot. [ABSTRACT FROM AUTHOR]

BACKGROUND: Ultrasonic pretreatment is a novel physical method that can be used in the extraction process of okra pectin. Real‐time online monitoring technologies were introduced in time and frequency domains when okra was pretreated. Preparation time of dried okra and yield of okra pectin were studied; and physicochemical properties of okra pectin were analyzed at the optimum ultrasonic parameter. RESULTS: Results showed that ultrasonic intensity of sweeping‐frequency ultrasonic (SFU) pretreatment was stronger than that of fixed‐frequency ultrasonic pretreatment (FFU). SFU pretreatment (60 ± 1 kHz) at 30 min had a strong ultrasonic voltage peak of 0.05387 V and signal power peak of −6.62 dBm. The preparation time of dried okra was 160 ± 14.14 min in the pretreated group, 44.83% lower than control without SFU pretreatment. The intercellular space was 56.03% higher than control. Water diffusion coefficient increased from 1.41 × 10−9 to 2.14 × 10−9 m2 s−1. Monobasic quadratic equations were developed for the monitored ultrasonic intensity and pectin yield. Compared to control, extraction yield (16.70%), pectin content (0.564 mg mg−1), solubility (0.8187 g g−1) and gel strength (30.91 g) were improved in the pretreated group. Viscosity decreased, and values of G′ and G″ crossing at 63 rad s−1 revealed the viscoelastic behavior and the beginning of viscous behavior with a sol state. CONCLUSION: Decrement of dried preparation time and increment of yield were achieved by ultrasonic pretreatment during the extraction process of okra pectin, and the relationship of ultrasonic intensity monitored by real‐time online technologies and yield was given. © 2021 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Sago starch extracted from the pith of sago palm using a traditional method has a low extraction yield. In this study, an effective extraction method for sago starch production with high extraction yield and acceptable starch quality was investigated using various pretreatment techniques, that is, ultrasonic, microwave, and enzymatic pretreatments, as well as combined pretreatment methods. The sago pith slurry was pretreated before subjecting to the normal process of sago starch extraction. The extracted sago starch was analyzed for extraction yield and physicochemical properties. Sago pith had high starch content of 82.0% (db). The highest extraction yields obtained using ultrasonic, microwave, enzymatic, and combined ultrasonic-enzymatic pretreatment methods were 71.5, 63.7, 71.4, and 72.5%, respectively, while the control method (without pretreatment) provided 61.0% extraction yield. The peak viscosity and color L* value of all extracted sago starches met the requirements of edible sago starch. Concerning the effective pretreatment method in terms of reduced time and energy consumption, while providing high extraction yield and acceptable starch quality, the ultrasonic pretreatment was recommended. The highest yielding ultrasonic pretreatment conditions were found to be 10% w/w sago pith slurry, 160W power input, and 7 min pretreatment time. [ABSTRACT FROM AUTHOR]

Generally, ultrasound irradiation is required throughout the reaction for fatty acid methyl esters (FAME, namely, biodiesel) production, which is energy-consuming and difficult to scale-up. In order to improve the industrial application of ultrasonic technology, a systematic study of ultrasonic pretreatment solid basic (NaSiO)-catalyzed transesterification for FAME production from cottonseed oil was carried out, and the effect of ultrasonic waves on the properties of NaSiO catalyst was assessed by X-ray diffraction (XRD), Fourier transform Infrared (FTIR) and scanning electron microscopy (SEM) characterization of fresh and collected catalysts. An ultrasonic frequency of 30 kHz, ultrasonic power of 200 W and ultrasonic pretreatment irradiation time of 30 min was determined to guarantee a satisfactory degree of transesterification. The optimum production was achieved in the reaction system at 45 °C with methanol/cottonseed oil molar ratio 5:1, catalyst dosage 3% and stirring speed 350 rpm resulting in a FAME yield of above 97% after 60 min of reaction under mechanical stirring with the ultrasonic pretreatment process. The new process has a shorter reaction time, a more moderate reaction temperature, a less amount of methanol and catalyst than only the mechanical stirring process without essential damage to activity and the structure of catalyst. These results are of great significance for applying the ultrasonic pretreatment method to produce FAME. [ABSTRACT FROM AUTHOR]

The effects of ultrasonic pretreatment on the liquefaction of corn starch at a high concentration were investigated using viscosity and reducing sugar content as the endpoints. The mechanism of the process was also analyzed. The results showed that the viscosity of sonicated starch paste was lower and the reducing sugar content was higher than those of a native control. Therefore, ultrasonic pretreatment could lead to more efficient liquefaction of corn starch at a high concentration. The main reasons are likely to be that ultrasonic pretreatment increase the specific surface area of the starch granules, producing a rough and holey surface, looser granule structure, and lower crystallinity. Also, ultrasonic pretreatment decreases the weight average molar mass, and increases the amylose content. As a result of these changes, the starch granules undergo increased enzymatic degradation during gelatinization. Ultrasonic pretreatment may also directly break starch chains to a certain extent. [ABSTRACT FROM AUTHOR]

ABSTRACT In this study, the effect of osmotic pretreatments (with or without ultrasound) in combination with hot-air or microwave-assisted hot-air drying methods on the texture, microstructure, color and water activity of dried cranberries were investigated. Osmotic pretreatments were done in a ternary solution (sucrose-NaCl-water) under three different temperatures: 30, 40 and 50C. The concentrations of osmotic solutions were 40, 50 and 60% of sucrose and 0, 4 and 8% of NaCl. Also, the influence of the two levels of frequency of ultrasound (35 and 130 kHz) on the quality properties was investigated. Our results showed lower hardness and water activity ( aw) when higher temperature, sucrose and salt were used. Applying ultrasound reduced the hardness and aw of samples. With increasing the frequency of ultrasound, hardness ( N) and aw were decreased. Microwave energy reduced drying time and can modify the structure, texture strength and color of the final product. PRACTICAL APPLICATIONS Cranberry contains high levels of phytochemicals, which have health-promoting properties. Some of these phytochemicals, such as anthocyanins, act as an antioxidant, reducing the oxidative damage to cells, which can lead to cancer, heart disease and other degenerative diseases. Recently, cranberry products have been used with the hope of preventing or treating urinary tract infections or Helicobacter pylori infections, which can lead to stomach ulcers, or to prevent dental plaque. Osmotic dehydration is a suitable way to produce shelf-stable products or partially dehydrated foods without enduring heat damage. The osmotically dehydrated cranberries can be consumed as healthy snacks or can be suited to a wide range of food formulations, including jams or sweets. [ABSTRACT FROM AUTHOR]