Ketone Content Research Articles

Comprehensive characterization and comparison of aroma profiles of rambutan seed oils using GC-MS and GC-IMS combined with chemometrics

BackgroundAroma significantly influences the quality of rambutan seed oil. Nonetheless, few studies have examined the volatile composition of rambutan seed oil. Thus, there is a need for a comprehensive characterization of the aroma profile of rambutan seed oil.MethodsThis study systematically investigated and compared the aroma characteristics of three types (BR-4, BR-5 and BR-7) of rambutan seed oils using HS-SPME-GC-MS and HS-GC-IMS techniques, augmented by chemometric modeling.ResultsGC-MS identified 135 volatile compounds, primarily hydrocarbons and esters, while GC-IMS characterized 35 compounds, mainly aldehydes and alcohols. Multivariate statistical analyses revealed significant differences in the aroma profiles among the oil samples. BR-5 exhibited the highest levels of aldehydes and hydrocarbons, whereas BR-7 demonstrated the highest content of esters and ketones. 21 and 15 differentially volatile compounds were extracted from the datasets obtained via GC-MS and GC-IMS. These compounds primarily comprised esters (floral and fruity) and aldehydes (green and fatty), interacting to create the distinctive aroma profiles of the three rambutan seed oils.ConclusionThis study provides theoretical support for evaluating the flavor characteristics and utilization potential of rambutan seed oil.

Effects of surimi by-product hydrolysates on processing quality and difference analysis of volatile compounds of silver carp surimi gel

The aim of this study was to investigate the effects of surimi by-product hydrolysates (SBPHs) on the processing quality, gel characteristics, microstructure, and volatile compounds of surimi. The results showed that the addition of SBPHs improved the water holding capacity (95.18% and 94.32%), texture property, and gel characteristic (546.04 g cm) of the surimi gel, reduced the cooking loss (7.15%) and aperture area (34.10%) of the surimi gel (P < 0.05), causing no difference in their whiteness (P > 0.05). The SBPHs reduced the free water and increased the immobilized water of the gel. At the same time, SBPHs made tighter cross-linking of the surimi gel proteins. The results of gas chromatography-ion mobility spectrometry showed that 62 volatile flavor compounds were detected in each group of surimi, and the relative contents of aldehydes, alcohols, and ketones were relatively high. A total of 19 volatile flavor compounds were selected as the potential markers in samples by orthogonal partial least square siscriminant analysis. The additions of SBPHs (0.6% and 1.2%) in this study were much lower than those of commercial cryoprotectant (6%). In conclusion, SBPHs emerges as a potential cryoprotectant for the surimi industry and have promising advantages in enhancing the quality of surimi.

Effects of Phaffia rhodozyma on microbial community dynamics and tobacco quality during tobacco fermentation.

Carotenoids are important precursors of various aroma components in tobacco and play an important role in the sensory quality of tobacco. Phaffia rhodozyma is a species of Xanthophyllomyces capable of synthesizing a highly valuable carotenoid-astaxanthin, but has not yet been used in improving tobacco quality. The dynamic changes of microbial community and metabolites during tobacco fermentation were analyzed in combination with microbiome and metabolome, and the quality of tobacco after fermentation was evaluated by sensory scores. P. rhodozyma could grow and produce carotenoids in tobacco extract, with a maximum biomass of 6.50 g/L and a maximum carotenoid production of 36.13 mg/L at 100 g/L tobacco extract. Meanwhile, the correlation analysis combined with microbiome and metabolomics showed that P. rhodozyma was significantly positively correlated with 11 metabolites such as 6-hydroxyluteolin and quercetin. Furthermore, the contents of alcohols, ketones and esters, which were important aromatic components in fermented tobacco, reached 77.57 μg/g, 58.28 μg/g and 73.51 μg/g, increasing 37.39%, 265.39% and 266.27% compared to the control group, respectively. Therefore, the aroma and flavor, and taste scores of fermented tobacco increased by 0.5 and 1.0 points respectively. This study confirmed that P. rhodozyma fermentation could effectively improve the sensory evaluation of tobacco, and provided a novel microbial fermentation method to improve tobacco quality.

Dynamic Changes of Active Components and Volatile Organic Compounds in Rosa roxburghii Fruit during the Process of Maturity.

Rosa roxburghii (R. roxburghii), native to the southwest provinces of China, is a fruit crop of important economic value in Guizhou Province. However, the changes in fruit quality and flavor during R. roxburghii fruit ripening have remained unknown. Here, this study investigated the changes of seven active components and volatile organic compounds (VOCs) during the ripening of the R. roxburghii fruit at five different ripening stages including 45, 65, 75, 90, and 105 days after anthesis. The results indicated that during the ripening process, the levels of total acid, vitamin C, and soluble sugar significantly increased (p < 0.05), while the levels of total flavonoids, superoxide dismutase (SOD), and soluble tannin significantly decreased (p < 0.05). Additionally, the content of total phenol exhibited a trend of first decreasing significantly and then increasing significantly (p < 0.05). A total of 145 VOCs were detected by HS-SPME-GC-MS at five mature stages, primarily consisting of aldehydes, alcohols, esters, and alkenes. As R. roxburghii matured, both the diversity and total quantity of VOCs in the fruit increased, with a notable rise in the contents of acids, ketones, and alkenes. By calculating the ROAV values of these VOCs, 53 key substances were identified, which included aromas such as fruit, citrus, green, caramel, grass, flower, sweet, soap, wood, and fat notes. The aromas of citrus, caramel, sweet, and wood were predominantly concentrated in the later stages of R. roxburghii fruit ripening. Cluster heatmap analysis revealed distinct distribution patterns of VOCs across five different maturity stages, serving as characteristic chemical fingerprints for each stage. Notably, stages IV and V were primarily characterized by a dominance of alkenes. OPLS-DA analysis categorized the ripening process of R. roxburghii fruit into three segments: the first segment encompassed the initial three stages (I, II, and III), the second segment corresponded to the fourth stage (IV), and the third segment pertained to the fifth stage (V). Following the variable importance in projection (VIP) > 1 criterion, a total of 30 key differential VOCs were identified across the five stages, predominantly comprising ester compounds, which significantly influenced the aroma profiles of R. roxburghii fruit. By integrating the VIP > 1 and ROAV > 1 criteria, 21 differential VOCs were further identified as key contributors to the aroma changes in R. roxburghii fruit during the ripening process. This study provided data on the changes in quality and aroma of R. roxburghii fruit during ripening and laid the foundation for the investigation of the mechanism of compound accumulation during ripening.

Brassinolide and gibberellin promote grape fruit development and quality

Brassinosteroid (BR) and Gibberellins (GA) are important hormones that significantly influences grapeberry development and ripening. In the present study, grape clusters were soaked separately with EBR (Epi brassinolide), GA3, and EBR+GA3 during fruit development. Results showed that anthocyanin content, soluble solids, and titratable acid content were all enhanced by EBR treatment, however fruit weight, transverse and longitudinal longitude, and hardness were not significantly changed, furthermore, GA3 treatment increased the fruit weight, longitudinal and transverse longitude, and hardness, decreased titratable acid, and increased the solid acid ratio; The EBR+GA3 significantly improved grape fruit quality, increased fruit anthocyanin content, reduced titratable acid content, improved sugar-acid ratio, and significantly improved fruit weight, transverse and longitudinal longitude, and hardness. EBR and GA3 treatment increased the contents of alcohols, esters, ketones, terpenes, and phenols in aroma substances, and glucose and fructose. They also increased the sugar, aroma, and anthocyanin metabolism-related genes, while down-regulated the expression of acid-related genes. EBR also increased the GA metabolism associated genes, but GA3 decereaed BR metabolism assocated genes. BR and GA had a crosstalk of that VvGAI could interact with VvBZR1, VvGAI could inhibit the VvBZR1 binding to the VvGA20ox2 promoter that decreased the VvGA20ox2 gene expression, but EBR and GA3 could alleviate the inhibition. In conclusion, both BR and GA alone could improve fruit quality to some extent, and the combination of them can better integrate the advantages of single-use to improve the fruit quality and enhance the commerciality of the grape fruit.

Antimicrobial pullulan packaging materials embedded with starch/thymol nanoemulsion via dynamic high-pressure micro-fluidization for strawberry preservation

Thymol/waxy maize starch nanoemulsion (TWSN) was successfully prepared via dynamic high-pressure micro-fluidization (DHPM) and applied in pullulan-based active food packaging material (P-TWSN). The properties of TWSN and its effect on the structural and physical-chemical properties of P-TWSN were then investigated. Concurrently, the impact of TWSN (0, 5, 15, 20, 25 mL) on the storage quality and flavor substances of strawberries coated by film-forming solution (FFS) were investigated by gas chromatography-ion mobility spectrometry (GC-IMS). The results demonstrated that the prepared TWSN exhibited remarkable storage stability, maintaining a particle size of 127.9 ± 1.02 nm and a ζ-potential of −32.4 ± 0.42 mV. As TWSN concentration increased, P-TWSN exhibited a smooth and compact morphology, characterized by the presence of bubble-like pores and granular protrusions. Additionally, the FTIR peaks corresponded to the stretching vibration of -OH group of TWSN and related materials were shifted to lower wavenumbers. Furthermore, the materials with increasing content of TWSN exhibited excellent water solubility, enlarged WVP, stable thermal property and superior antibacterial capacity against gram-positive (S.aureus) than gram-negative (E. coli) bacteria. Strawberry samples sprayed by FFS with 20 mL TWSN exhibited the slowest decline in shrinkage, weight loss, titrable acidity, highest value of firmness, total soluble solids, and lower content of ascorbic acid and viable microorganisms in comparison with other dosages. Additionally, the contents of esters and alcohols in treated strawberries reached the summit on the fourth day of storage and subsequently declined, while the ketone content exhibited a downward trend with increasing TWSN, particularly in the samples with 20 and 25 mL TWSN. The studies identified an efficient method for preparing starch-based nanoemulsion by DHPM, which could be prospective in bio-active packaging materials.

Effect of fatty acid composition on the volatile compounds of pasteurized milk during low-temperature storage

The change in milk fat during storage greatly influences its flavor. This study investigates the effect of fatty acid composition on milk flavor by analyzing volatile compounds in pasteurized whole milk (PWM) and pasteurized skim milk (PSM) during storage at 4 °C. 33 types of volatile compounds were detected and the content of ketones was highest, followed by esters and aldehydes. Based on variable importance in projection and relative odor activity value, 2-hexenal dimer, acetic acid ethyl ester dimer, acetic acid ethyl ester, and butanal were identified as the key differential volatile compounds. These compounds were found in higher concentrations in PWM than in PSM, indicating a close relationship with the changes in the fatty acid composition of milk fat. Among 11 fatty acids detected in PWM, the content of saturated fatty acids (SFA) and polyunsaturated fatty acids (PUFA) decreased by 0.69 % and 49.1 %, respectively, while the content of monounsaturated fatty acids increased by 46.8 % during 15 days storage, which suggests that the oxidation of SFA and PUFA contributed more to the volatile compound formation. Correlation analysis between fatty acid composition and volatile compounds found that fatty acid C18:2 and C16:0 were strongly associated for 2-hexenal, acetic acid ethyl ester, and butanal. These fatty acids were mainly derived from neutral lipids or phospholipids. These findings provide a new perspective for the formation pathway of milk flavor.

Study on the influence of Ni/La2O3/CeO2 composite catalysts on the characteristics and stability of biomass pyrolysis components

The impact of adding La2O3 and CeO2 separately or in combination to a Ni-Al2O3 catalyst on the volatile components of biomass pyrolysis is examined in this study. This study focuses on the effects of varying pyrolysis temperatures and catalyst usage cycles on catalytic reforming, evaluating the resulting pyrolysis yield, syngas composition, and catalyst stability. Catalyst characteristics are also analyzed. The results of this study show that the Ni-Al2O3 catalyst modified with La2O3 alone produces a 9 % reduction in tar yield and a 20 % increase in the CO + H2 fraction of the pyrolysis gas compared to the control group. When modified with CeO2 alone, the Ni-Al2O3 catalyst keeps a tar conversion efficiency above 43 % after ten consecutive usage cycles. The addition of La2O3 and CeO2 simultaneously led to a 19 % increase in hydrogen yield, with the absolute content of alcohols, ketones, and esters reaching zero at 850°C.

Pyrolysis characteristics of different types of tobacco and its correlation with the released aroma components under heating condition

An in-depth insight into the pyrolysis characteristics of tobacco is of great significance for the utilization of tobacco wastes. The effects of glycerol addition on the pyrolysis characteristics and distribution of aroma components of four types of tobacco was investigated in this study by using thermogravimetry and self-built rapid heating furnace capture and GC-MS analysis. Further, correlation network analysis was used to study the correlation between pyrolysis characteristics and released aroma components. It was found that the thermal weight loss behavior of different samples exhibited both commonalities and differences, the thermal weight loss process could be divided into four stages. After the application of glycerol, the overall performance of all types of tobacco leaves at stage II showed that DTGmax2 and WL2 increased, and glycerol had a relatively obvious effect on the pyrolysis characteristic parameters of flue-cured tobacco. Pyrolysis kinetic analysis based on Coats-Redfern method showed that the activation energy and pre-exponential factor of tobacco samples were decreased after the addition of glycerol. Under the heating condition, the total amount of released aroma components from each type of tobacco followed the order of burley tobacco > flue-cured tobacco >oriental tobacco > yellow sun-cured tobacco. The release amount of heterocyclic and olefins compounds from burley tobacco were higher, while flue-cured tobacco released higher contents of esters, ketones and furans compounds. The addition of glycerol promoted the release of aroma components. In terms of correlation, Tmax2 was negatively correlated with esters, aldehydes, and furans compounds, and positively correlated with DTGmax3. Tmax3 was significantly correlated with a lot of indicators, positively with acids, aldehydes, and furans compounds, but negatively with olefins and heterocyclic compounds.

Screening of lactic acid bacteria with the ability to reduce goaty flavor related fatty acids in goat milk

In this study, we conducted sensory evaluation and gas chromatography–mass spectrometry analysis on fermented goat milk samples prepared by 12 strains of lactic acid bacteria (LAB) isolated from goat milk to screen for strains with the ability to reduce the goaty flavor. The bacterial counts of fermented goat milk was 7.07–9.01 log CFU/mL. The electronic nose distinguished fresh goat milk (FGM) and fermented goat milk, and the electronic tongue results showed that Leuconostoc citreum 1, 4, 20, 22, 32, and 57, Latilactobacillus curvatus 144 and 147 imparted fermented goat milk a taste different from FGM. Overall, Leuconostoc citreum 57, Leuconostoc citreum 126, Latilactobacillus curvatus 142, Latilactobacillus curvatus 143, and Latilactobacillus curvatus 147 were screened with the ability to improve the flavor of goat milk. They gave fermented goat milk a goat flavor score lower than or equal to FGM. And the fermented goat milk samples 57, 126, 142, 143, and 147 contained 25, 22, 15, 24, and 17 volatile flavor compounds, respectively, with a greater variety and content of ketones and aldehydes and lower levels of hexanoic acid, octanoic acid, and decanoic acid than FGM. However, the pH and WHC results indicated that the application of these strains as secondary cultures is necessary. Our finding provides basic research data to improve the flavor of goat milk products.

Optimizing Split-reduced drip fertigation schemes of Arabica coffee based on soil microcosms, bean yield, quality and flavor in dry-hot region of southwest China

As a characteristic cash crop in Yunnan Province, China, Arabica coffee ranks first in the country in terms of cultivation area and production, but has always suffered from poor soil nutrient management and a lack of scientific basis for fertilization. It is not clear how to improve the soil microecological environment using split-reduced drip fertigation at different reproductive stages of Arabica coffee to improve bean yield and quality. Therefore, a two-year (2020–2022) field experiment was conducted on 5-year-old Arabica coffee trees in a dry-hot region with five split-drip fertigation patterns, F450, F600, F750, F900 and F1050. Using the local conventional fertilization (Fertilizer of 900 kg ha−1 year−1 only in berry expansion, and no fertilization in early flowering and berry ripening) as the control (CK). The effects of different fertilization modes on soil microecological environment, bean yield, nutritional quality and characteristic flavor were studied, and a comprehensive benefit evaluation model to assess bean yield and nutritional quality under different fertilization modes was established. The results showed that F900 significantly increased soil nitrate nitrogen, available phosphorus, available potassium, microbial population and enzyme activities at early flowering and berry ripening stages compared to CK, while F900 reduced soil nitrate nitrogen, available phosphorus and available potassium but increased soil enzyme activity and microbial population at the berry expansion stage. Compared with CK, F450 decreased bean yield, caffeine and chlorogenic acid content by 31.83 %, 23.73 % and 13.48 %, respectively, while F750 increased two-year average yield, raw bean fat, caffeine and chlorogenic acid content by 20.52 %, 12.37 %, 5.48 % and 11.17 %, respectively. The two-year average yield of F600 showed less difference from CK. Marginal yield was positive and then negative with increasing fertilizer application. Dry bean yield decreased at a total fertilizer application of 900 kg ha−1 year−1. Correlation analyses showed a positive correlation between soil microbial environment and nutrient quality of coffee beans, while different correlations were found between nutrients and volatiles at dark and medium roasting levels. Cluster analysis revealed that the relative contents of aldehydes, alcohols, phenols, pyridines, and pyrroles were higher under dark roasted condition, while the relative contents of ketones, esters, acids, and pyrazines were higher under medium roasted condition. Based on the Entropy weight-TOPSIS method, F750 had the highest combined benefits in terms of yield increase and quality improvement, and the total fertilizer application decreased by 16.67 % compared to CK, thus F750 treatment was the most suitable split-drip fertigation strategy for Arabica coffee in the dry-hot region of Yunnan. This study provided a reference for drip fertigation systems of Arabica coffee in dry and hot regions.

Use of GC-IMS and Stoichiometry to Characterize Flavor Volatiles in Different Parts of Lueyang Black Chicken during Slaughtering and Cutting.

Chilled and cut chicken is preferred by consumers for its safeness and readiness to cook. To evaluate the quality characteristics of various chilled chicken products, differences in volatile organic components (VOCs) of six different cut parts (breast, back, leg, heart, liver, and gizzard) of Lueyang black chicken were characterized through gas chromatography-ion mobility spectroscopy (GC-IMS) combined with stoichiometry. A total of 54 peaks in the signal of VOCs were detected by GC-IMS, and 43 VOCs were identified by qualitative analysis. There were 22 aldehydes (20.66-54.07%), 8 ketones (25.74-62.87%), 9 alcohols (4.17-14.69%), 1 ether (0.18-2.22%), 2 esters (0.43-1.54%), and 1 furan (0.13-0.52%), in which aldehydes, ketones, and alcohols were the main categories. Among the six cut parts, the relative content of aldehydes (54.07%) was the highest in the gizzard, and the relative content of ketones (62.87%) was the highest in the heart. Meanwhile, the relative content of alcohols (14.69%) was the highest in the liver. Based on a stable and reliable predictive model established by orthogonal partial least squares-discriminant analysis (OPLS-DA), 3-hydroxy-2-butanone (monomer and dimer), acetone, 2-butanone monomer, hexanal (monomer and dimer), isopentyl alcohol monomer, and n-hexanol monomer were picked out as characteristic VOCs based on variable importance in projection (VIP value > 1.0, p < 0.05). Principal component analysis (PCA) and the clustering heatmap indicated that the characteristic VOCs could effectively distinguish the six cut parts of Lueyang black chicken. The specific VOCs responsible for flavor differences among six different cut parts of Lueyang black chicken were hexanal (monomer and dimer) for the gizzard, 2-butanone monomer and hexanal dimer for the breast, hexanal monomer for the back, 3-hydroxy-2-butanone monomer for the leg, 3-hydroxy-2-butanone (monomer and dimer) for the heart, and acetone and isopentyl alcohol monomer for the liver. These findings could reveal references for quality assessment and development of chilled products related to different cut parts of Lueyang black chicken in the future.

Assessment of quality differences between wild and cultivated fruits of Rosa roxburghii Tratt

Cultivated and wild Rosa roxburghii Tratt were investigated to determine the intrinsic causes of the quality differences. The cultivated fruit, Guinong No. 5 (GNNF) was larger, heavier, and had less color difference. Its juice contained higher levels of soluble solids and tannins. The wild variety (WRRT) had higher concentrations of condensed tannins, polyphenols and flavonoids. Artificial sensory and electronic taste tests indicated GNNF had a lower astringent and bitter taste compared to WRRT. A total of 80 flavour substances were identified by gas chromatography‒mass spectrometry (GC-MS). The relative contents of esters, organic acids, ketones, alcohols, aldehydes and aromatic hydrocarbons were higher in GNNF than in WRRT. Caffeylalcohol, catechin, quinidine, pantothenic acid and five bitter amino acids were high in GNNF. The high contents of bitter substances such as limonin, daidzein, and rutaevin were responsible for the quality differences between WRRT and GNNF.

Combining lipase enzymatic techniques and antioxidants on the flavor of structured lipids (SLs) prepared from goat butter and coconut oil

Enzymatic transesterification can improve the quality of goat butter, however, the high temperature may lead to oil oxidation and produce a bad taste. In this study, goat butter (GB) and coconut oil (CO) were combined to synthesize structured lipids (SLs) by enzymatic transesterification, and antioxidants were added to inhibit oxidation to improve the oils’ flavor. The Lipozyme TLIM and tert-butylhydroquinone (TBHQ) were screened for SLs synthesis. The contents of SLs were 56.24% under the optimal conditions of 8 h reaction time, 5°C reaction temperature, 8% enzyme dosage, and 3:1 (w/w) substrate ratio, and the addition of antioxidants had no significant effect on the contents of SLs. It was demonstrated that short-chain fatty acids in the SLs were significantly reduced by 59.2%, and the medium-chain fatty acids were increased by 54.9% compared to GB. One hundred volatile compounds were identified in the lipid samples and classified as (1) long-chain alkane aromatic components and aromatic components, which remarkably decreased by 58.9%, and (2) alcohols, aldehydes, and ketones, which increased by 12.9%, through using solid-phase microextraction coupled with gas chromatography-mass spectrometry (SPME-GC-MS) and electronic nose. The relative aroma activity value (ROAV) of 9 key volatile aroma components was higher than 1 in the SLs, which greatly contributed to the reduction of goaty flavor and increasing cream flavor. The results suggested that the goaty flavor of GB could be significantly reduced by decreasing the short-chain fatty acids contents in SLs through enzymatic transesterification with CO, while the addition of antioxidants efficiently inhibited excessive lipids oxidation and increased the content of long-chain aldehydes, ketones, and lactones, thus enhancing the cream flavor, which had great potential to be utilized as natural food flavor additives.

Explorative Study on Volatile Organic Compounds of Cinnamon Based on GC-IMS.

Cinnamon is one of the most popular spices worldwide, and volatile organic compounds (VOCs) are its main metabolic products. The misuse or mixing of cinnamon on the market is quite serious. This study used gas chromatography-ion migration spectroscopy (GC-IMS) technology to analyze the VOCs of cinnamon samples. The measurement results showed that 66 VOCs were detected in cinnamon, with terpenes being the main component accounting for 45.45%, followed by aldehydes accounting for 21.21%. The content of esters and aldehydes was higher in RG-01, RG-02, and RG-04; the content of alcohols was higher in RG-01; and the content of ketones was higher in RG-02. Principal component analysis, cluster analysis, and partial least squares regression analysis can be performed on the obtained data to clearly distinguish cinnamon. According to the VIP results of PLS-DA, 1-Hexanol, 2-heptanone, ethanol, and other substances are the main volatile substances that distinguish cinnamon. This study combined GC-IMS technology with chemometrics to accurately identify cinnamon samples, providing scientific guidance for the efficient utilization of cinnamon. At the same time, this study is of great significance for improving the relevant quality standards of spices and guiding the safe use of spices.

Factors influencing synergistic pyrolysis of biomass and polypropylene for alcohols and hydrocarbon production

Results are presented on the co-pyrolysis of different blends of rapeseed stalk and plastic polypropylene (100:0, 75:25, 50:50, 25:75 and 0:100) using thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy and pyrolyzer-gas chromatography/mass spectrometry (Py-GC/MS), independently. The effect of temperature (450, 550 and 650 °C) on the synergistic effect between rapeseed stalk and polypropylene at different blend ratios as well as on the yield and amounts of alcohols and hydrocarbons produced are presented. The thermogravimetric analysis results showed that at the same temperature, increase of polypropylene in the mixture, gradually increased the intensity and rate of pyrolysis reaction. The weight loss data revealed improved pyrolysis during the process. The Fourier transform infrared spectroscopy results showed that the transmittance of ketones, esters and acids increased while the content of ketones, esters and acids decreased with increased polypropylene in the mixture. The pyrolyzer-gas chromatography/mass spectrometry results showed that temperature and feedstock mixture ratio had an impact on the yield and amounts of alcohols and hydrocarbons. The pyrolysis effect was most favorable at 550 °C temperature and rapeseed stalk/polypropylene mixture ratio of 1:3. These results provide some practical insights on clean energy recovery from mixtures of agricultural residues and waste plastics using thermochemical conversion.

Characterization of the color, physicochemical properties, organic acids, and aroma profiles of kiwifruit wines by different fermentation patterns and fining stages

The high contents of pectins, proteins, and polyphenols in the raw materials pose a challenge to the fining of fruit wines. This research investigated the impacts of juice, mash, and mash with peel fermentations on the color, organic acids, and aroma of kiwifruit wines, and further explored the effects of adding gelatin and bentonite before and during fermentations on the quality of the wines. The findings revealed that while the chroma and hue of the three fermentation patterns did not exhibit significant differences, but the contents of esters, aldehydes, and terpenes were higher in the juice and mash fermentations. The contents of total volatiles, acids, and ketones were the highest in the mash fermentation. Besides, total acidity, alcohol, chroma, hue, clarity, varieties and contents of volatiles were significantly affected by the fining stages. Clarity during fermentation fining increased from 79.72% of the control to 84.91%–88.29%. There was a minor difference in the content of the major volatiles between the control and the later stage of fermentation bentonite (LFB) fining, and the esters content of LFB fining increased by 51.87%. It indicated that mash fermentation and LFB fining were a concise and effective way to improve the clarity and flavor of kiwifruit wine.

Degradation mechanism of cuticular wax composition and surface properties of bamboo culm during storage

Cuticular wax on bamboo culm forms a kind of protective biointerface during growing and degrades after harvesting leading to the deterioration of surface quality and protection function during storage. The degradation mechanism of the cuticular wax and surface property of harvested bamboo culm during storage is still unclear. To understand it, the microstructure of cuticular wax on the harvested bamboo culm was characterized and composition content was analyzed by GC-MS as well as the contact angle and color of bamboo culm surface were tested after the bamboo culm was stored in four simulated seasons: spring, summer, autumn and winter. The results showed that the more wax deposited on bamboo culm surface during storage, and the thickness of cuticular wax increased. During storage, the content of alkanes, alcohols and total ketone in bamboo culm cuticular wax decreased as well as the contents of terpenoids and esters increased. This suggested that the degradation of cuticular wax on bamboo culm should be due to the hydrolysis of alkane into fatty acids and terpenoids.The surface contact angle of stored bamboo culm decreased and the color of bamboo culm changed. The contact angle of the stored bamboo culm surface reduced 12.24%, 25.53%, 9.76%, 1.85% compared with the fresh bamboo culm. The surface color of bamboo culm was related to the content of cuticular wax and weight loss of bamboo culm and was the joint function of weight loss and wax content change.

Insight into pyrolysis behaviors of cedar under different atmospheres via a fixed-bed reactor

Pyrolysis, as an efficient route for biomass, usually suffers the influence of pyrolysis atmosphere by the interaction with free radicals from biomass pyrolysis. To investigate the effects of pyrolysis atmosphere on cedar pyrolysis, several atmospheres including CH4, H2, CO2, CO, CH4/CO2 and H2/CO were used for CS pyrolysis on a fixed-bed reactor and the pyrolysis process was revealed based on products distribution, tar quality and compositions. The results show that the components in pyrolysis atmosphere apparently affect the distribution of pyrolysis products and play different roles in cedar pyrolysis. Tar yields under different atmospheres follow the order of H2/CO > H2 > CH4/CO2 > CO2 > CO > N2 > CH4. The highest tar yield of 45.5 wt.% was obtained under H2/CO atmosphere at 600 °C. Char yield was decreased under H2 by suppressing secondary reaction and followed the order of H2 < H2/CO < CH4/CO2 < N2 < CO2 < CO < CH4. The content of ketones was improved under CO2 atmosphere. The introduction of H2 mainly increases naphthalenes, benzenes, ketones and phenols; while the formation of acids, esters, aldehydes and furans was inhibited under CO atmosphere. Integrated process of biomass pyrolysis with CO2 reforming of CH4 can greatly increase tar yield and change tar compositions, which is ascribed to the participation of H-rich free radicals from CO2 reforming of CH4. This work provides a route to improve the yield of pyrolysis tar and adjust tar components.

Effects of Heating Treatment on the Physicochemical and Volatile Flavor Properties of Argentinian Shortfin Squid (Illex argentinus).

In this study, the effect of different heating temperatures (80, 90, 100, and 121 °C) on the physicochemical and volatile flavor properties of fried mantles (Argentinian shortfin) was investigated. The squid mantles were soaked in a maltose syrup solution (20% w/v) for 10 s and fried in soybean oil for 10 s (160 °C), vacuum-packed, and processed at different temperatures for 10 min. Then, the squid mantles were subjected to colorimetric analysis, sensory evaluation, free amino acid analysis, and texture profile analysis. In addition, the volatile organic compounds (VOCs) in the squid mantles were analyzed. The results revealed that lower treating temperatures (80 and 90 °C) improved the chromatic and textural properties, along with organoleptic perception. Additionally, the content of amino acid in the squid mantles treated at 121 °C was significantly lower than that of the samples treated at other temperatures (p < 0.05). Headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) was used to detect 41 VOCs, including their monomers and dimers. Among these detected VOCs, the contents of alcohols, ketones, and pyrazines were positively correlated with temperature. However, the content of aldehydes in the squid mantles gradually decreased as the heating temperature increased (p < 0.05). The combined HS-GC-IMS and E-nose results revealed that the lower temperatures (80 and 90 °C) were more suitable for flavor development and practical processing. This study provides valuable information for properly controlling the heating process of squid products, as well as flavor and practical applications for the aquatic industry.