Effect of dielectric barrier discharge cold plasma treatments on flavor fingerprints of brown rice

Characterizing the composition of volatile compounds in different types of Chinese bacon using GC-MS, E-nose, and GC-IMS

Chinese bacon is highly esteemed by consumers worldwide due to its unique aroma. The composition of volatile organic compounds (VOCs) varies significantly among different types of Chinese bacon. This study analyzed the VOCs of Chinese bacon from Sichuan, Hunan, Guangxi, and Shaanxi provinces using gas chromatography-mass spectrometry (GC-MS), an electronic nose (E-nose), and gas chromatography-ion mobility spectrometry (GC-IMS). The results demonstrate that the combination of GC-MS and GC-IMS effectively distinguishes Chinese bacon from different regions. Notably, Guangxi bacon lacks a smoky aroma, which sets it apart from the other types. However, it contains many esters that play a crucial role in its flavor profile. In contrast, phenols, including guaiacol, which is typical in smoked bacon, were present in the bacon from Sichuan, Hunan, and Shaanxi but were absent in Guangxi bacon. Furthermore, Hunan bacon exhibited a higher aldehyde content than Sichuan bacon. 2-methyl-propanol and 3-methyl-butanol were identified as characteristic flavor compounds of Zhenba bacon. This study provides a theoretical foundation for understanding and identifying the flavor profiles of Chinese bacon. Using various analytical techniques to investigate the flavor compounds is essential for effectively distinguishing bacon from different regions.

Air and argon cold plasma effects on lipolytic enzymes inactivation, physicochemical properties and volatile profiles of lightly-milled rice

This study investigated the effectiveness of cold-plasma treatment using air and argon as input gas on deactivation of lipolytic enzymes in lightly-milled-rice (LMR). The results showed no significant inactivation in lipase and lipoxygenase using air-plasma. However, using argon as input gas, the residual activities of lipase and lipoxygenase were reduced to 64.51 % and 29.15 % of initial levels, respectively. Argon plasma treatment resulted in more substantial augmentation in peak and breakdown viscosities of LMR starch, suggesting an enhancement in palatability of cooked LMR with increased stickiness and decreased hardness. In contrast to the decrease in volatile compounds in LMR following argon plasma treatment, the concentrations of several prevalent aroma compounds, including 1-hexanol, 1-hexanal, and 2-pentylfuran, exhibited significant increments, reaching 1489.70 ng/g, 3312.10 ng/g, and 58.80 ng/g, respectively. These findings suggest the potential for enhancing various facets of the commercial qualities of LMR by utilizing different input gases during plasma treatment.

Incorporating edible oil during cooking tailors the microstructure and quality features of brown rice following heat moisture treatment

While brown rice (BR) has numerous nutritional properties, the consumption potential of which is seriously restricted since the poor cooking quality and undesirable flavor. Here, edible oils (pork lard and corn oil, 1-5 wt%) were incorporated during the cooking of BR following heat moisture treatment. Incorporating corn oil rather than lard significantly ameliorated the texture properties (e.g. hardness, cohesiveness, and chewiness) and sensory properties of cooked BR. Both lard- and corn oil-incorporated cooked BR showed obvious structural changes accompanied by the formation of amylose-lipid complexes during cooking. It was confirmed that the incorporation of lard and corn oil allowed a higher degree of short-range molecular order, more V-type starch crystallites, and elevated nano-structural arrangements. Additionally, a decreased hardness (from 559.04 g to 424.18 g and 385.91 g, respectively) and enriched resistant starch (RS) were also observed, the highest RS content (15.95 % and 16.32 %, respectively) was observed when 1 wt% of lard and corn oil were incorporated.

A Comprehensive Study on the Influence of Superheated Steam Treatment on Lipolytic Enzymes, Physicochemical Characteristics, and Volatile Composition of Lightly Milled Rice

Enzyme inactivation is crucial for enhancing the shelf life of lightly milled rice (LMR), yet the impact of diverse superheated steam (SS) treatment conditions on lipolytic enzyme efficiency, physicochemical properties, and volatile profiles of LMR remains unclear. This study investigated varying SS conditions, employing temperatures of 120 °C, 140 °C, and 160 °C and exposure times of 2, 4, 6, and 8 min. The research aimed to discern the influence of these conditions on enzyme activities, physicochemical characteristics, and quality attributes of LMR. Results indicated a significant rise in the inactivation rate with increased treatment temperature or duration, achieving a notable 70% reduction in enzyme activities at 120 °C for 6 min. Prolonged exposure to higher temperatures also induced pronounced fissures on LMR surfaces. Furthermore, intensive SS treatment led to a noteworthy 5.52% reduction in the relative crystallinity of LMR starch. GC/MS analysis revealed a consequential decrease, ranging from 44.7% to 65.7%, in undesirable odor ketones post-SS treatment. These findings underscore the potential of SS treatment in enhancing the commercial attributes of LMR.

The Effects of Genotype × Environment on Physicochemical and Sensory Properties and Differences of Volatile Organic Compounds of Three Rice Types (Oryza sativa L.)

Understanding the effects of genotype, environment and their interactions on rice quality is of great importance for rice breeding and cultivation. In this study, six rice varieties with two indica, two japonica and two indica-japonica types of rice were selected and planted at ten locations in Zhejiang Province to investigate the genotype (G) × environment (E) on physicochemical and sensory properties and the differences of volatile organic compounds (VOCs) among the three types of rice. Analysis of variances showed that apparent amylose content (AC), total protein content (PC), alkali spreading value (ASV), RVA profiles, and appearance (ACR), palatability (PCR), and sensory evaluation value (SEV) of cooked rice and texture of cooled cooked rice (TCCR) were mainly affected by genotypic variation, whereas the smell of cooked rice (SCR) was mainly affected by environment (p < 0.05). The G × E effect was significant for most parameters. The weather in the middle and late periods of filling had important effects on the formation of rice quality, especially on setback (SB) and pasting temperature (PT) (p < 0.01). They were negatively correlated with the texture of cooked rice (TCR) and SEV (p < 0.05). Peak viscosity (PV) and breakdown (BD) were positively related to the sensory evaluation parameters (p < 0.01) and could be used to predict cooked rice quality. A total of 59 VOCs were detected, and indica, japonica and indica-japonica had 9, 6 and 19 characteristic compounds, respectively. The principal component analysis showed that the physicochemical and sensory properties and VOCs of indica-japonica rice were more stable than those of indica and japonica rice at ten locations in Zhejiang Province. It is helpful for rice breeders to understand how the environment affects the physicochemical, sensory properties and VOCs of the three rice types, and it is also important for food enterprises to provide rice products with stable quality.

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.

Characteristics of changes in volatile organic compounds and microbial communities during the storage of pickles

The variations of volatile organic compounds (VOCs) and microbial communities of three pickles during storage at 4°C for one week were analyzed by headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS), high-throughput sequencing, and Spearman correlation analysis. A total of 50 VOCs were identified from three pickles. During storage, most alcohols, aldehydes, ketones, and esters decreased, while acids increased, and sulfides, alkenes, and phenols were relatively equal. Firmicutes, Cyanobacteria, and Proteobacteria were the predominant bacterial phyla, and Weissella, Streptophyta, Leuconostoc, Bacillariophyta, and Lactobacillus were the predominant bacterial genera in three pickles. The bacterial diversity level significantly decreased during storage (P < 0.05). Spearman correlation coefficient indicated that Leuconostoc, Lactobacillus, and Weissella were highly correlated with the flavor of pickles, while Bacillariophyta and Streptophyta were highly correlated with the flavor formation of pickles during storage. These results could contribute to a better understanding of the impact of bacteria in flavor formation during pickle storage.

Potential volatile markers of brown rice infested by the rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae)

The rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae) could cause significant grain loss by feeding internally on seeds. In this study, we tried to analyze the volatile compounds in non-infested and S. oryzae-infested brown rice during different storage periods to identify potential markers in S. oryzae-infested brown rice and facilitate pest monitoring during brown rice storage. Headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) and headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) were used to identify the volatile compounds. On the basis of GC-MS and GC-IMS data, a reliable method to distinguish between non-infested and S. oryzae-infested brown rice was discovered using partial least squares-discriminant analysis (PLS-DA). 1-Octen-3-ol, 1-hexanol and 3-octanone were co-selected as potential markers because their variable importance in projection (VIP) was greater than 1 in both models. The current study's findings lay a foundation for further research on the brown rice infestation mechanism and safe storage monitoring.

Effect of storage on the nutritional and antioxidant properties of brown Basmati rice

The purpose of the present study is to evaluate the effect of storage time and temperature on the nutritional and antioxidant values of different varieties of brown rice. PARB approved indigenous Basmati varieties (Basmati 86, Basmati 515, Basmati super, Basmati super fine and Basmati kainat) were procured and initially tested for physicochemical parameters, including moisture, ash, lipids, proteins, carbohydrates, and fibers from the brown rice powder. Similarly, antioxidant capacity of these brown rice samples was assessed in terms of total phenolic content and 2,2-diphenyl-1-picrylhydrazyl radical-scavenging potential. Samples of brown rice were stored for 3 and 6 months at 25 and 5°C. On increasing the storage time and temperature, antioxidant activity of rice decreases up to 50%. Nutritional parameters, such as minerals, carbohydrates, and fatty acids were characterized using UV/Vis spectrophotometer, ICP-OES, GC-MS, and HPLC, revealing significant changes in the chemical composition of brown rice. Observation indicates that storage at high temperatures leads to a rapid decrease in carbohydrate and moisture content than at lower temperatures. The protein and ash content remains controlled and integrate with the mineral composition found. Decrease in the glucose and fructose amount was observed in brown rice varieties except for Basmati super fine and Basmati kainat at 5°C. Regarding fatty acids, oleic and linoleic acids were prominent in oils extracted from the different brown rice varieties, and their content was reduced during the storage due to conversion to behenic, and erucic acids, respectively. From the present study, it can be concluded that low storage temperatures reduce the loss of nutrients, offering better nutritional quality for the consumer.

Understanding the Palatability, Flavor, Starch Functional Properties and Storability of Indica-Japonica Hybrid Rice

The rice quality and starch functional properties, as well as the storability of three YY-IJHR cultivars, which included YY12 (biased japonica type YY-IJHR), YY1540 (intermedius type YY-IJHR) and YY15 (biased indica type YY-IJHR), were studied and compared to N84 (conventional japonica rice). The study results suggested that the three YY-IJHR varieties all had greater cooking and eating quality than N84, as they had lower amylose and protein content. The starch of YY-IJHR has a higher pasting viscosity and digestibility, and there was a significant difference among the three YY-IJHR cultivars. Rice aroma components were revealed by GC-IMS, which indicated that the content of alcohols vola-tile components of YY-IJHR were generally lower, whereas the content of some aldehydes and esters were higher than N84. In addition, YY-IJHR cultivars’ FFA and MDA contents were lower, which demonstrated that YY-IJHR had a higher palatability and storability than those of N84 in fresh rice and rice stored for 12 months. In conclusion, this study suggested that YY-IJHR had better rice quality and storability than N84. PCA indicated that the grain quality and storability of YY12 and YY15 were similar and performed better than YY1540, while the aroma components and starch functional properties of YY-IJHR cultivars all had significant differences.

Effect of Flaxseed Supplementation in Diet of Dairy Cow on the Volatile Organic Compounds of Raw Milk by HS-GC-IMS

Flaxseed supplementation in diet of dairy cow can effectively enhance the production of ω-3 polyunsaturated fatty acids (n-3 PUFA) in raw milk, which further give rise to the changes of volatile organic compounds (VOCs). In this study, we used headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) to investigate the VOCs in milk from cows fed three different diets (CK: supplemented with 0 g/d flaxseed; WF: 1,500 g/d whole flaxseed and GF: 1,500 g/d ground flaxseed). A total of 40 VOCs including three acids, six esters, 11 aldehydes, seven alcohols, 13 ketones were identified in all the raw milk samples. Compared with GF supplementation, suppling with WF could influence more compounds in raw milk (GF: five compounds; WF: 22 compounds). Supplementation with WF could increase the concentration of nonanal, heptanal, hexanal, which could cause the occurrence of off-flavors, and reduce the concentration of hexanoic acid (monomer; M), 2-hexanol, ethanol (M), 2-heptanone (dimer; D), 2-pentanone (M), 2-pentanone (D), acetoin (M) in raw milk. GF supplementation in diet could reduce the 2-pentanone (M), 2-pentanone (D). In addition, principal component analysis (PCA) based on the signal intensity of identified VOCs indicated that it is possible to distinguish between the CK and WF milk. However, GF milk could not be distinguished from CK milk. The results demonstrate that compared with GF milk, WF supplementation in diet of dairy cows could increase fishy (heptanal) cardboard-like (pentanal) flavor in milk and decrease sweet (hexanoic acid, 2-heptanone), fruity (ethyl butanoate, ethyl hexanoate, 2-heptanone) flavor which may lead the milk less acceptable. In conclusion, compared with WF, GF supplementation in diet of dairy cow showed higher increase in n-3 PUFA in raw milk, and less influence in VOCs of raw milk and this study might provide theoretical supports for the production of milk rich in n-3 PUFA.

Effect of Plasma Activated Water on Selected Chemical Compounds of Rocket-Salad (Eruca sativa Mill.) Leaves

Plasma activated water (PAW) has proven to be a promising alternative for the decontamination of rocket leaves. The impact of PAW on the volatile profile, phytosterols, and pigment content of rocket leaves was studied. Leaves were treated by PAW at different times (2, 5, 10, and 20 min). Compounds of the headspace were detected and quantified using GC–MS analysis. A total of 52 volatile organic compounds of different chemical classes were identified. Glucosinolate hydrolysis products are the major chemical class. PAW application induced some chemical modifications in the volatile compounds. Changes in the content of the major compounds varied with the increase or decrease in the treatment time. However, PAW-10 and -2 were grouped closely to the control. A significant decrease in the content of β-sitosterol and campesterol was observed after PAW treatment, except for PAW-10, which showed a non-significant reduction in both compounds. A significant increase in β carotene, luteolin, and chlorophyll b was observed after the shortest treatment time of PAW-2. A reduction in chlorophyll content was also observed, which is significant only at longer treatment, or PAW-20. Overall, PAW has proven to be a safe alternative for rocket decontamination.

Integrated Analysis of Metabolome and Volatile Profiles of Germinated Brown Rice from the Japonica and Indica Subspecies

In the present study, germinated brown rice (GBR) from three Japonica and three Indica rice cultivars were subjected to metabolomics analysis and volatile profiling. The statistical assessment and pathway analysis of the metabolomics data demonstrated that in spite of significant metabolic changes in response to the germination treatment, the Japonica rice cultivars consistently expressed higher levels of several health-promoting compounds, such as essential amino acids and γ-aminobutyric acid (GABA), than the Indica cultivars. No clear discriminations of the volatile profiles were observed in light of the subspecies, and the concentrations of the volatile organic compounds (VOCs), including alkenes, aldehydes, furans, ketones, and alcohols, all exhibited significant reductions ranging from 26.8% to 64.1% after the germination. The results suggest that the Japonica cultivars might be desirable as the raw materials for generating and selecting GBR food products for health-conscious consumers.