To establish the safe and reproducible effects of cold plasma (CP) technology on food products, this study evaluated the gelatinization parameters, fatty acid profile, and hygroscopic properties of rice grains repeatedly treated with low-pressure radiofrequency (RF) helium CP (13.56 MHz, 140 Pa, 120 W-20s, 0–4 times, and 300 g sample). Compared with the untreated (zero times) sample, with an increase in CP treatment times from one to four on rice, the water contact angle and cooking time decreased, while the water absorption rate and freshness index increased, and the pH value remained unchanged. CP repeating treatments essentially had no effect on the gelatinization enthalpy, but significantly increased the peak temperature of gelatinization. From the pasting profile of rice that has been repeatedly CP treated, the peak, breakdown, and setback viscosities in flour paste decreased. CP repeating treatments on rice did not change the short-range molecular order of starch. Compared with the untreated sample, the first helium CP treatment maintained the content of C18:1n9c, C18:2n6c, and C18:3n3, but the second to fourth CP treatment significantly decreased contents of these fatty acids (FAs) as the C18:0 content increased. The first three CP treatments can increase the water and sucrose solvent retention capacity in rice flours. CP repeatedly treated rice first exhibits the similar monolayer water content and solid surface area of water sorption. Principal component analysis shows that contact angle, pasting parameters, and fatty acid profile in milled rice are quite sensitive to CP treatment. Results support that the effect of low-pressure RF 120W helium CP treatment 20 s on rice grains is perdurable, and the improvement of CP intermittent treatments on rice cooking and pasting properties is an added benefit, and the hygroscopic properties of rice was kept.

As an anti-staling agent in bread, the desorption isotherm of polydextrose has not been studied due to a very long equilibrium time. The adsorption and desorption isotherms of five Chinese polydextrose products were measured in the range of 0.1–0.9 a_w and 20–35 °C by a dynamic moisture sorption analyzer. The results show that the shape of adsorption and desorption isotherms was similar to that of amorphous lactose. In the range of 0.1–0.8 a_w, the hysteresis between desorption and adsorption of polydextrose was significant. The sorption isotherms of polydextrose can be fitted by seven commonly used models, and our developed seven-parameter polynomial, the adsorption equations of generalized D’Arcy and Watt (GDW) and Ferro-Fontan, and desorption equations of polynomial and Peleg, performed well in the range of 0.1–0.9 a_w. The hysteresis curves of polydextrose at four temperatures quickly decreased with a_w increase at a_w ˂ 0.5, andthereafter slowly decreased when a_w ≥ 0.5. The polynomial fitting hysteresis curves of polydextrose were divided into three regions: ˂0.2, 0.2–0.7, and 0.71–0.9 a_w. The addition of 0–10% polydextrose to rice starch decreased the surface adsorption and bulk absorption during the adsorption and desorption of rice starch, while it increased the water adsorption value at a_w ≥ 0.7 due to polydextrose dissolution. DSC analysis showed that polydextrose as a gelling agent inhibited the retrogradation of rice starch, which could be used to maintain the quality of cooked rice.

To reduce the hard texture of cooked early indica rice, two types of polydextrose (ST with 1% moisture content (MC) and XG with 4.7% MC) were added at 0%, 3%, 5%, 7%, and 10%, respectively, to the cooking milled rice polished from the paddies of the 2.5-year-stored IP46 variety and the newly harvested Sharuan Nian (SRN) variety. Compared with early indica rice without polydextrose, the cooking time was significantly reduced and gruel solids loss was increased with the increase in polydextrose addition. Generalized linear model (GLM) analysis shows that both polydextrose equally reduced the hardness, adhesive force, adhesiveness, cohesiveness, gumminess, and chewiness of the cooked early indica rice, and maintained the resilience. They also significantly reduced the rapid viscosity analysis (RVA) parameters like the peak viscosity, trough viscosity, breakdown viscosity, final viscosity, and setback viscosity of early indica rice, and significantly increased the peak time and pasting temperature. Both polydextrose significantly increased the gelatinization temperature of rice flour measured by a differential scanning calorimeter (DSC)and reduced the gelatinization enthalpy and aging. Compared with the sample without polydextrose, the addition of two types of polydextrose significantly increased the dough development time of rice flour measured by a Mixolab, but reduced the maximum gelatinization torque, starch breakdown and setback torque, and heating rate. XG had a higher capability in decreasing the rice cooking time and the aging of retrograded rice flour paste, and in increasing the score of the appearance structure and taste in cooked rice than ST; ST was better in decreasing the gelatinization enthalpy of rice flour paste and the setback torque of rice dough than XG, maybe due to the polymer molecular weight. Microstructure analysis showed that adding polydextrose promoted the entry of water molecules into the surface of the rice kernel and the dissolution of starch, and the honeycomb structure was gradually destroyed, resulting in larger pores. The cross-section of the cooked rice kernel formed cracks due to the entry of water, the cracks in the IP46 variety were larger and shallower than those in the SRN variety, and there were more filamentous aggregates in the IP46 variety. Polydextrose addition aggravated the swelling of starch granules, made the internal structure loose and produced an obvious depression in the central area of the cross-section, forming soft and evenly swollen rice kernels. These results suggest that polydextrose addition can significantly improve the hard texture of cooked early indica rice and shorten the cooking time.

This study explored the effects of adding a newly developed type of polydextrose on the appearance, sensory score, and textural parameters of steamed bread and the microstructure of dough, as well as the pasting, thermal, and thermal mechanical properties of high-gluten wheat flours. The results revealed that, compared with a control sample, 3–10% of polydextrose addition significantly increased the hardness, adhesiveness, gumminess, and chewiness of steamed bread, but other textural parameters like springiness, cohesiveness, and resilience remained basically the same. Further, in contrast to the control sample, 3–10% polydextrose addition significantly reduced the specific volume and width/height ratio of steamed bread but increased the brightness index, yellowish color, and color difference; improved the internal structure; and maintained the other sensory parameters and total score. Polydextrose addition decreased the peak, trough, final, breakdown, and setback viscosity of the pasting of wheat flour suspension solutions but increased the pasting temperature. Polydextrose additions significantly reduced the enthalpy of gelatinization and the aging rate of flour paste but increased the peak temperature of gelatinization. A Mixolab revealed that, with increases in the amount of added polydextrose, the dough’s development time and heating rate increased, but the proteins weakened, and the peak torque of gelatinization, starch breakdown, and starch setback torque all decreased. Polydextrose additions increased the crystalline regions of starch, the interaction between proteins and starch, and the β-sheet percentage of wheat dough without yeast and of steamed bread. The amorphous regions of starch were increased in dough through adding polydextrose, but they were decreased in steamed bread. Further, 3–10%of polydextrose addition decreased the random coils, α-helixes, and β-turns in dough, but the 3–7% polydextrose addition maintained or increased these conformations in steamed bread, while 10% polydextrose decreased them. In unfermented dough, as a hydrogel, the 5–7% polydextrose addition resulted in the formation of a continuous three-dimensional network structure with certain adhesiveness and elasticity, with increases in the porosity and gas-holding capacity of the product. Moreover, the 10% polydextrose addition further increased the viscosity, freshness, and looseness of the dough, with smaller and more numerous holes and indistinct boundaries between starch granules. These results indicate that the 3–10% polydextrose addition increases the chewiness and freshness of steamed bread by improving the gluten network structure. This study will promote the addition of polydextrose in steamed bread to improve shelf-life and dietary fiber contents.

Supposing that polydextrose molecules could improve the hard texture of cooked rice based on intermolecular interactions and forming a hydrogel-like network structure, this study added polydextrose (moisture content 1%) at 0%, 3%, 5%, 7%, and 10% concentrations to rice (cv. Super Qianhao, SQ) milled from a 3-year-stored paddy and compared their cooking properties, their cooked rice texture, the pasting and thermal properties of their flours, the thermo-mechanical characteristics of their flour dough, and the microstructure of their cooked rice grains with a newly harvested japonica rice cv. Nanjing 5 (NJ5). With an increase in polydextrose addition, a General Linear Model (GLM) analysis showed that the cooking times of two japonica rice varieties was significantly (p < 0.05) reduced, and their gruel solid loss increased. Adding polydextrose significantly reduced the hardness, springiness, gumminess, and chewiness of cooked rice and increased the cohesiveness and resilience. By increasing polydextrose addition in rice flours, the peak, breakdown, and setback viscosities of pasting were significantly decreased, but the pasting temperature and peak time increased. Adding polydextrose reduced the gelatinization enthalpy and increased gelatinization peak temperature of the rice flour and significantly decreased the ageing of the retrograded rice flour paste stored at 4 °C when measured at 21 days. A Mixolab test showed that the stability time of the rice flour dough increased, and the protein weakening, gelatinization peak torque, and starch breakdown, as well as the starch setback and the speeds of heating, gelatinization, and enzymatic degradation all decreased. The addition of 5–10% polydextrose significantly reduced the amorphous and crystalline regions of starch and relative percent of β-sheet in cooked rice grains, with an increase in the relative percent of α-helix, random coil, and β-turn. Observing the microstructure, we confirmed that polydextrose addition facilitated the formation of a soft and evenly swollen honeycomb structure of the cooked rice. These results suggest that polydextrose might decrease the cooked rice hardness and improve the eating quality of sea rice through intermolecular interactions.

As an emerging oilseed crop in China, peony seed oils account for 0.41% of the annual production of Chinese edible vegetable oils, and the oil-type peony seed is rich in alpha-linolenic acid (ALA). Moisture content and temperature are key factors in the storage of oilseeds. In this study, the adsorption and desorption isotherms of ten species of peony seeds and one species of cake were determined in the range of 20–30 °C and 10–90% equilibrium relative humidity (ERH). The adsorption and desorption isotherms of peony seeds and cake were type II (sigmoidal) or type III curves. Nine equilibrium moisture content (EMC) equations were used to fit the isotherms of peony samples, with the optimal equations being our developed 7-parameter polynomial (Poly), modified Halsey equation (MHAE), and modified Oswin equation (MOE). For Poly, the fitting parameter determination coefficient (R²) was 0.9816–0.9986, and the mean relative error (MRE) was 0.83–6.52%; for MHAE, R² was 0.7815–0.9973, and MRE was 4.18–17.84%. Poly contains the terms of temperature and ERH interaction; therefore, Poly could analyze the safe moisture content of peony seeds and cake during storage and transportation, and the three-parameter reversible MHAE could be used for calculating the sorption isosteric heats. The adsorption monolayer moisture content (M₀) in peony seeds and cake estimated by MGAB were 3.64 ± 0.42% and 4.28%, respectively, while their desorption M₀ values, respectively, were 6.21 ± 0.47% and 4.83%. At ERH ≤ 65%, for preventing the growth of storage pests and fungi, the absolutely safe storage moisture content (MC) predicted by Poly at 25 °C and 65% ERH was 12.48% wet basis (w.b.) for seeds and 11.92% for cake. The heat of sorption of peony seeds and cake approached that of pure water at about 11% and 15% w.b. MC estimated by the MHAE model, respectively. Microstructure analysis showed that the rich liposomes in peony seeds were attached to the inner surface of the cell wall and the outer surface of the protein storage vacuole, and the rich protein bodies and hydrophilic polysaccharides explained why the safe storage moisture for yellow peony seeds was higher than for Ziyan Feishuang seeds. This study provides the basic data for drying simulation, and the safe storage and transportation of peony seed and cake products.