Effects of non‐thermal plasma treating wheat kernel on the physicochemical properties of wheat flour and the quality of fresh wet noodles

Hierarchical structural modification of starch via non-thermal plasma: A state-of-the-art review

The hierarchical architecture of natural and processed starches with different surface and internal structures determines their final physicochemical properties. However, the oriented control of starch structure presents a significant challenge, and non-thermal plasma (cold plasma, CP) has gradually been used to design and tailor starch macromolecules, though without clear illustration. In this review, the multi-scale structure (i.e., chain-length distribution, crystal structure, lamellar structure, and particle surface) of starch is summarized by CP treatment. The plasma type, mode, medium gas and mechanism are also illustrated, as well as their sustainable food applications, such as in food taste, safety, and packaging. The effects of CP on the chain-length distribution, lamellar structure, amorphous zone, and particle surface/core of starch includes irregularity due to the complex of CP types, action modes, and reactive conditions. CP-induced chain breaks lead to short-chain distributions in starch, but this rule is no longer useful when CP is combined with other physical treatments. The degree but not type of starch crystals is indirectly influenced by CP through attacking the amorphous region. Furthermore, the CP-induced surface corrosion and channel disintegration of starch cause changes in functional properties for starch-related applications.

Influence of Non-Thermal Plasma Treatment on Structural Network Attributes of Wheat Flour and Respective Dough

Due to its "generally recognized as safe status" (GRAS) and moderate treatment temperatures, non-thermal plasma (NTP) has lately been considered a suitable replacement for chemicals in the modification of food properties and for preserving food quality. One of the promising areas for the application of NTP is the treatment of wheat flour, leading to improved flour properties and product quality and consequently to higher customer satisfaction. In the present research, the German wheat flour type 550, equivalent to all-purpose flour, was treated using NTP in a rotational reactor to determine the influence of short treatment times (≤5 min) on the properties of flour (moisture and fat content, protein, starch, color, microbial activity, and enzymes), dough (visco-elastic properties, starch, wet and dry gluten, and water absorption), and baking products (color, freshness, baked volume, crumb structure, softness, and elasticity). Based on the properties of NTP, it was expected that even very short treatment times would have a significant effect on the flour particles, which could positively affect the quality of the final baking product. Overall, the experimental analysis showed a positive effect of NTP treatment of wheat flour, e.g., decreased water activity value (<0.7), which is known to positively affect flour stability and product shelf life; dough stability increased (>8% after 5 min. treatment); dough extensibility increased (ca. 30% after 3 min treatment); etc. Regarding the baking product, further positive effects were detected, e.g., enhanced product volume (>9%), improved crumb whiteness/decreased crumb yellowness, softening of breadcrumb without a change in elasticity, and limited microorganism and enzymatic activity. Furthermore, no negative effects on the product quality were observed, even though further food quality tests are required. The presented experimental research confirms the overall positive influence of NTP treatment, even for very low treatment times, on wheat flour and its products. The presented findings are significant for the potential implementation of this technique on an industrial level.

Non-thermal plasma modulation of the interaction between whey protein isolate and ginsenoside Rg1 to improve the rheological and oxidative properties of emulsion

Molecular interaction forces regulate the interfacial properties of oil-in-water emulsion and play a key role in the rheology and stability of the emulsion in the food industry. In this study, the effects of non-thermal plasma (NTP) treatment on the structural and functional properties of whey protein isolate (WPI) and its binding interaction with ginsenoside Rg₁ (GR₁) were investigated. The results based on surface hydrophobicity, infrared spectroscopy and fluorescence spectroscopy test showed that the NTP treatment induced the unfolding of the structure of WPI and promoted the binding affinity between WPI and GR₁. By comparing with untreated WPI (an α-helix content of 19.63 % and a β-sheet content of 31.66 %), there was a greater decrease in α-helix content and an increase in β-sheet content of WPI in N₂₀-WPI (α-helix = 9.63 %, β-sheet = 39.63 %) and N₂₀-WPI-GR₁ (α-helix = 4.98 %, β-sheet = 48.66 %) groups. Importantly, the NTP treatment increased the interfacial adsorption and antioxidant capacity of the WPI-GR1 complexes, which contributed to the improvement of the rheological properties and oxidation stability of the emulsion. As a result, the NTP treatment could markedly improve the rheological and antioxidative properties of the WPI-GR₁ complexes and the NTP-treated WPI-GR₁ emulsions was more stable than that untreated. The present research indicated that NTP-treated formation of protein-saponin complexes could enhance the functional properties of the proteins, thus expanding their application as functional ingradients in nutritionally fortified food.