Evaluation of quality deterioration of dried whole-wheat noodles with extrusion-stabilized bran and germ during storage

Gas chromatography-ion mobility spectrometry (GC-IMS) technique and its recent applications in grain research

Grains are the primary source of food for most people worldwide and constitute a major source of carbohydrates. Many novel technologies are being employed to ensure the safety and reliability of grain supply and production. Gas chromatography-ion mobility spectrometry (GC-IMS) can effectively separate and sensitively detect volatile organic compounds. It possesses advantages such as speed, convenience, high sensitivity, no pretreatment, and wide applicability. In recent years, many studies have shown that the application of GC-IMS technology for grain flavor analysis can play a crucial role in grains. This article elucidates the working principle of GC-IMS technology, reviews the application of GC-IMS in grains in the past 5 years. GC-IMS technology is mainly applied in four aspects in grains. In grain classification, it distinguishes varieties, quality, origin, production year, and processing methods based on the trace differences in volatile organic compounds, thereby fulfilling various grain classification requirements such as origin tracing, geographical indication product recognition, variety identification, production year identification, and detection of counterfeit and inferior grain samples. In optimizing the processing technology of grains and their products, it can improve food flavor, reduce undesirable flavors, and identify better processing parameters. In grain storage, it can determine the storage time, detect spoilage phenomena such as mold and discoloration during storage, eliminate pests affecting storage, and predict the vitality of seeds after storage. In aroma evaluation of grains and their processed products, it can assess the impact of new raw materials, new technologies, fermentation processes, and even oral processing on the quality of grain products. This article also summarizes the characteristics of GC-IMS technology, compiles typical grain flavor compounds, and provides prospects for the future application of GC-IMS. © 2024 Society of Chemical Industry.

Three thermal treated methods improve physicochemical and functional properties of wheat bran-germ and the bran-germ containing products

BACKGROUND

To fully investigate the effect of different stabilization methods on WBG in the same environment, we studied the effect of microwaving, baking, and extrusion on the nutritional, physicochemical, and processability properties of WBG and whole wheat bran-germ noodle (WBGN). Principal component analysis was used to comprehensively evaluate the qualities of WBG and WBGN. Machine learning-based research was conducted to predict the quality of WBGN based on the features of WBG.

RESULTS

The results showed that three methods improved antioxidant ability, bound flavonoids, bound and total phenolics, and the processing properties in WBG (P < 0.05). Extruded-WBG showed a lower polyphenol oxidase activity, lipase activity (35.02 ± 2.02 U and 20.29 ± 0.47 mg g^-1 ) and particle size (54.08 ± 0.38 μm), and higher water hold capacity (2.60 ± 0.68%) and bound phenolic levels. The enhanced quantity of bound polyphenols had a major role in the increased antioxidant potential of WBGN. Extruded-WBGN showed higher antioxidant ability for 2,2-diphenyl-1-picrylhydrazyl (171.28 ± 3.16 μmol Trolox eq kg^-1 ). The extruded-WBGN had high concentrations of WBG aroma compounds, and low contents of bitterness and raw bran-germ flavor compounds. Next, the enzymatic activity, powder properties, color, and antioxidant capacity of WBG were further utilized to predict the polyphenolic, flavonoids, flavor compounds, and antioxidant capacities of WBGN, where the R² value of the model exceeded 0.90. The best comprehensive quality modification method of the WBG and WBGN was extrusion, followed by baking and microwaving.

CONCLUSION

The present study shows that extrusion is a promising way to improve WBG into a nutritious and flavorful cereal food ingredient. © 2023 Society of Chemical Industry.

Flavor properties of Chinese noodles processed by dielectric drying

Volatile organic compounds (VOCs) significantly impact food flavor. In this work, Electron nose (E-nose), head space solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS), and head space-gas chromatography-ion mobility spectrometry (HS-GC-IMS) techniques were applied to analyze different drying effects: microwave, hot air, and radio frequency on the aroma of Chinese noodles. E-nose analysis suggests that aromatic differences are mainly from broad range-methane. HS-SPME-GC-MS and HS-GC-IMS identified 47 and 26 VOCs in the fresh and dried noodles, respectively. The VOCs in the dried noodles were mainly aldehydes, alcohols, and esters. Drying significantly reduced the types of VOCs in Chinese dried noodles. Microwave dried noodles exhibited the strongest aroma after the shortest time of treatment, suggesting microwave drying may be the best drying method for noodles. Using aromatic analysis, this paper provides useful information for understanding the flavor of flour products and offers new ideas for drying noodles.

Microwave-assisted enzymatic hydrolysis of wheat germ albumin to prepare polypeptides and influence on physical and chemical properties

Wheat germ albumin (WGA) is rich in nutrients and contains a number of antioxidant polypeptides. The effects of microwave-assisted alkaline protease, neutral protease, papain and compound protease on the degree of hydrolysis of WGA and the clearance rate of DPPH• were comparatively studied. The results showed that papain had the best proteolytic activity. The functional properties of WGA and its hydrolysis polypeptides were determined. The results showed that the solubility of WGA increased after papain hydrolysis, and the apparent viscosity and foam stability reduced. Compared with the amino acids of WGA, the proportions of proline, histidine, glycine, lysine, and glutamic acid in the enzymatic hydrolysis products increased, while the proportions of leucine, phenylalanine, arginine and isoleucine decreased.  After papain hydrolysis, the surface structure was loose, and the surrounding blocks became more rounded.