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Postharvest deterioration is among the major challenges for the fruit industry. Regulation of the fruit softening rate is an effective strategy for extending shelf-life and reducing the economic losses due postharvest deterioration. The tomato myoinositol monophosphatase 3 gene SlIMP3, which showed highest expression level in fruit, was expressed and purified. SlIMP3 demonstrated high affinity with the L-Gal 1-P and D-Ins 3-P, and acted as a bifunctional enzyme in the biosynthesis of AsA and myoinositol. Overexpression of SlIMP3 not only improved AsA and myoinositol content, but also increased cell wall thickness, improved fruit firmness, delayed fruit softening, decreased water loss, and extended shelf-life. Overexpression of SlIMP3 also increased uronic acid, rhamnose, xylose, mannose, and galactose content in cell wall of fruit. Treating fruit with myoinositol obtained similar fruit phenotypes of SlIMP3-overexpressed fruit, with increased cell wall thickness and delayed fruit softening. Meanwhile, overexpression of SlIMP3 conferred tomato fruit tolerance to Botrytis cinerea. The function of SlIMP3 in cell wall biogenesis and fruit softening were also verified using another tomato species, Ailsa Craig (AC). Overexpression of SlDHAR in fruit increased AsA content, but did not affect the cell wall thickness or fruit firmness and softening. The results support a critical role for SlIMP3 in AsA biosynthesis and cell wall biogenesis, and provide a new method of delaying tomato fruit softening, and insight into the link between AsA and cell wall metabolism.

To improve the uniformity of microwave heating and enhance the quality of continuous microwave drying for raspberry pulp, a self-developed programmable logic controller (PLC) control system with pulsed microwave output was implemented. The central composite experimental design method was employed to analyze the effects of four experimental factors, namely microwave duty cycle, pulse period, air velocity and drying time on the average temperature, temperature dispersion value, moisture content, moisture content dispersion value, anthocyanin retention rate, and anthocyanin retention rate dispersion value of raspberry pulp. The optimal process for pulsed microwave drying of raspberry pulp was obtained. Compared with dried pulp quality and uniformity indexes from pulsed microwave drying, commonly used feedback temperature control microwave drying, intermittent microwave drying, and continuous microwave drying processes to develop a continuous microwave drying quality optimization control system for raspberry pulp. The results showed that the magnetron from pulsed microwave drying in the form of pulse output rectangular wave form power through the PLC control system. Turning on the magnetron intermittently was more effective than continuous microwave heating. Pulsed microwave drying of raspberry pulp has better product quality and heating efficiency, lower cost and better reliability than feedback temperature control systems. The optimal process parameters for pulsed microwave drying were microwave duty cycle of 0.6, pulse period of 17 seconds, air velocity of 1.9 m/s, and drying time of 12.5 minutes. Compared with continuous microwave drying, pulsed microwave drying resulted in the highest quality of dried pulp as a 35.31%±0.55% increase in anthocyanin retention, a 33.59%±0.23% increase under feedback temperature control, a 16.42%±0.18% increase under intermittent microwave drying. Pulsed microwave drying can control the power to reduce the dried fruit pulp temperature, improve the uniformity of post-drying quality and provide a basis for the industrial production of dried raspberry products. [ABSTRACT FROM AUTHOR]

To improve product quality and obtain suitable processing parameters for crab apple slices (CASs) produced by continuous microwave drying (CMD), the effects of processing parameters, including slice thickness, microwave power, air velocity, and conveyor belt speed, on the evaluation indexes in terms of temperature, moisture content, color (L*, a*, b*), hardness, brittleness, and total phenolic content of CASs were investigated via the response surface method. The results indicated that microwave power has the greatest effect on the evaluation indexes applied to the CASs under CMD, followed by air velocity, slice thickness, and conveyor belt speed. To produce the desired product quality, the appropriate parameters for CMD of CASs were optimized as 1.25 mm slice thickness, 14,630 W microwave power, 0.50 m·s−1 air velocity, and 0.33 m·min−1 conveyor belt speed. Following that, the moisture content under CMD was found to be 13.53%, the desired color, hardness 0.79 g, brittleness 12.97 (number of peaks), and the total phenolic content 5.48 mg·g−1. This research provides a theoretical framework for optimizing the processing parameters of CASs using the response surface method. [ABSTRACT FROM AUTHOR]

In order to obtain better quality cookies, food 3D printing technology was employed to prepare cookies. The texture, color, deformation, moisture content, and temperature of the cookie as evaluation indicators, the influences of baking process parameters, such as baking time, surface heating temperature and bottom heating temperature, on the quality of the cookie were studied to optimize the baking process parameters. The results showed that the baking process parameters had obvious effects on the texture, color, deformation, moisture content, and temperature of the cookie. All of the roasting surface heating temperature, bottom heating temperature and baking time had positive influences on the hardness, crunchiness, crispiness, and the total color difference (ΔE) of the cookie. When the heating temperatures of the surfac and bottom increased, the diameter and thickness deformation rate of the cookie increased. However, with the extension of baking time, the diameter and thickness deformation rate of the cookie first increased and then decreased. With the surface heating temperature of 180 °C, the bottom heating temperature of 150 °C, and baking time of 15 min, the cookie was crisp and moderate with moderate deformation and uniform color. There was no burnt phenomenon with the desired quality. Research results provided a theoretical basis for cookie manufactory based on food 3D printing technology. [ABSTRACT FROM AUTHOR]

To elucidate the utilization efficiency of microwave energy (UEME) of granular food, germinated brown rice (GBR) as a representational material, in a continuous microwave dryer, the propagation of microwave energy inside drying cavity and the effects of technology parameters on the energy consumption of GBR material layer were investigated by using numerical simulation and bench experiments. Results indicate that the transmission loss of microwave scatter from the waveguide ports decline with the increase of thickness of grain layer in drying cavity. The total absorption of microwave energy is achieved in the thickness of material processed exceeding critical depth of microwave penetration to reduce the scatter loss of microwave transmission. In microwave cavity, the dissipation of microwave energy inside material processed alters the modes and frequency of microwave propagation and resonance, and continuous movement and ventilation process may promote UEME due to the improvement of drying uniformity of GBR. High UEME may be achieved at the temperature of GBR material layer in range of 100 ± 5 °C till final moisture content of 14.5% (w.b.). The optimal technology parameters of microwave drying for GBR is obtained as microwave intensity of 2 W/g, ventilation velocity of 1.0–1.5 m/s, drying duration for per drying pass of 6 min, and the thickness of GBR layer of 8 mm to achieve high UEME. The research results provide significant insights to evaluate the electric field distribution and design industrial microwave dryer with high utilization efficiency of microwave energy. [ABSTRACT FROM AUTHOR]

Raspberry snack, as a novel berry product, has rich favor and high crisp taste, where controllable texture quality is conducive to the palatability of the snack. Determinative factors of microwave puffing in microwave intensity and duration and key property of material in Young's modulus were introduced to investigate the formation of texture quality of berry snack under microwave puffing. The results indicate that the microwave intensity has negative correlation with Young's modulus of raspberry chips, which causes the more porosity inside under microwave puffing. Reasonable Young's modulus of raspberry chips enhances the interior porosity and exterior expansion volume of raspberry snack due to the water vapor wrapped other than escaped. The greater microwave intensity results in the higher volume expansion of raspberry chips, in which the great volume expansion from porous pores structure confers moderate hardness. In microwave puffing, the formation of hardness and crispness of raspberry snack depend on microwave puffing parameters, leading to high temperature and great dehydration rate in quick puffing duration, in addition to Young's modulus of raspberry chips, where high dehydration rate accelerates water removal inside raspberry chips to form a harder texture with decreasing springiness, whereas low dehydration rate leads to the gentle change of springiness. Raspberry snack with uniform internal pores and regular shape forming desirable texture may be achieved under the microwave intensity of 7.5 W/g and the puffing duration of 6 min. This study indicates that high‐quality raspberry snack may be achieved via controlling heating rate in microwave puffing. [ABSTRACT FROM AUTHOR]

Suitable fissures in kernels and the golden yellow color are the desired visual quality to evaluate germinated brown rice (GBR) subjected to drying processing. To improve the visual quality of GBR dried in a continuous microwave dryer, the effects of microwave intensity (1–5 W/g), air velocity (0–2 m/s), drying duration for per drying pass (2–10 min), and material layer thickness (4–12 mm) on the formation of visual quality of GBR in terms of fissure and color were investigated by using bench experiments and numerical modeling. The results showed that temperature and moisture content of the final dried GBR had high uniformity in the continuous microwave dryer, and most of the dried GBR kernels were in a "mild" (1–2 fissures in kernels) and "moderate" (3–4 fissures in kernels) fissure degree at the microwave intensity of 2–3 W/g. The increasing air velocity may weaken the effects of interior stress caused by moisture content gradients on fissures in GBR kernel. The chroma b*, representing the golden yellow color index of GBR, significantly (P < 0.05) increased with the microwave intensity and the drying duration for per drying pass of 4–6 min. The material layer thickness lower than 10 mm was suitable for the formation of golden yellow color appearance of GBR. The simulation results confirmed that microwave intensity had a positive effect on the formation of fissures for GBR in a continuous microwave dryer due to the rising stress along the short-axis direction of GBR kernel. The distribution of moisture content inside GBR kernel was relatively uniform under the microwave intensity lower than 3 W/g, and the higher moisture content gradients aggravated the evolution of fissures in kernels. Considering the desired visual quality of the final GBR, the appropriate microwave drying conditions of GBR were developed as microwave intensity of 2 W/g, air velocity of 1.0–1.5 m/s, drying duration of 6 min for per drying pass and 8 mm material layer thickness, which induced the generation of suitable fissures and the formation of golden yellow color for GBR under the continuous microwave dryer. This study may provide a preference for the industrial application of microwave drying of cereal materials such as GBR. [ABSTRACT FROM AUTHOR]