Novel insight into the evolution of volatile compounds during dynamic freeze-drying of Ziziphus jujuba cv. Huizao based on GC-MS combined with multivariate data analysis

Foodomics uncovers functional and volatile metabolite dynamics in red raspberry chewable tablet optimized processing

Raspberries are known to contain valuable metabolites and possess a robust antioxidant capacity. However, the impact of different tablet processing stages on the nutritional content and flavor profile of raspberries remains unclear. The dynamic profile of functional and volatile metabolites was investigated through foodomics combined with UPLC-MS/MS-based widely targeted metabolomics and HS-SPME-GC-MS, and antioxidant capacities were assessed during tablet processing. 1336 functional metabolites and 645 volatile metabolites were identified. Results indicated tablets retained 34% ∼ 61% of the total volatile contents. In addition, the conversion intensity of functional metabolites was consistent with the order of "Tableting > Freeze-drying > Crushing". Compared to raspberry, tablets showed higher antioxidant activity, which was positively correlated with vitamin contents. This study elucidated that tablet formation demonstrated advantages in antioxidation and aroma retention, which may provide insights for enhancing quality during the tableting process.

The potential of glucosidase and glucose oxidase for aroma improvement in concentrated peach puree based on volatilomics and metabolomics

Cooked off-flavor was produced during the processing of concentrated peach puree (CPP), which led to aroma deterioration. Enzymatic treatment was beneficial in eliminating off-flavors and improving the aroma quality. Herein, the efficacy of glycosidase (AR2000), glucose oxidation (GOD), and their combination on the inhibition of off-flavors and aroma enhancement were evaluated. Compared with CPP, contents of benzaldehyde, benzyl alcohol, nonanal, and linalool increased by 198%, 1222%, 781%, and 71% after AR2000 treatment via the metabolisms of shikimate, glucose, linoleic acid, and linolenic acid, leading to the strengthening of floral and grassy. Due to the removal of 1-octen-3-one via linolenic acid metabolism, cooked off-flavor could be significantly weakened by GOD. Furthermore, Furthermore, the combination of AR2000 and GOD could not only inhibit the production of 1-octen-3-one to weaken the cooked note but also enhance grassy and floral attributes via the increase of aldehydes and alcohols.

Profiling flavor characteristics of cold brew coffee with GC-MS, electronic nose and tongue: effect of roasting degrees and freeze-drying

BACKGROUND

Roasting is an important process in the formation of coffee flavor characteristics, which determines the quality of coffee and consumer acceptance. However, the influence of roasting degree on the flavor characteristics of cold brew coffee has not been fully described.

RESULTS

In the present study, the flavor characteristics of cold brew coffee with different roasting degrees were compared in detail by using chromatographic and electronic sensory approaches, and the flavor changes induced by freeze-drying were investigated. Pyrazine and heterocyclic compounds were the main aroma compounds in coffee, and gradually dominated with the increase of roasting. Pyridine was consistently present in cold brew coffees of different roasting degrees and showed significant gradient of quantity accumulation. Aroma compounds such as pyrazine, linalool and furfuryl acetate were the main contributors to coffee roasting, floral and fruity flavor. Freeze-drying preserved the fruity and floral aromas of medium-roasted cold brew coffee, whereas reducing the bitterness, astringency and acidity properties that are off-putting to consumers.

CONCLUSION

The higher consumer acceptance and enjoyment in medium roast cold brew coffee may be related to its stronger floral and fruity aroma. The aroma profile qualities of freeze-drying processed medium roasted cold brewed coffee were more dominant and more suitable for freeze-drying processing than medium dark roasting. Application of freeze-drying for cold brew coffee will promote the convenience of drinking. The present study provides valuable technical guidance in improving the flavor and quality of cold brew coffee, and also promotes its commercialization process. © 2024 Society of Chemical Industry.

Revealing the mechanism of post-harvest processing on rose quality based on dynamic changes in water content, enzyme activity, volatile and non-volatile metabolites

Existing studies on post-harvest processing of edible roses have mainly focused on processing techniques and physicochemical properties of the final dried products, with limited studies on how changes in metabolites during processing affect the quality of these products. This study investigated changes in water content and status, enzyme activity, phenolic compounds, and volatile and non-volatile compounds during processing and revealed the mechanisms by which post-harvest processing (drying without blanching (WBD) and drying with blanching (BD)) affects the quality of dried roses by establishing their correlations. Results showed that the blanching reduced the relative content of free water and water activity, thus reducing the subsequent drying time and enzyme activity. The BD method caused higher levels of phenolic compounds than the WBD method in terms of gallic acid, ellagic acid, epicatechin, and quercetin. The OPLS-DA analysis identified 6 differential volatiles out of 72 detected volatiles, contributing to the unique aroma of dried roses by activating olfactory receptors through hydrogen bonding and hydrophobic interactions. 58 differential metabolites were screened from 964 non-volatile metabolites. KEGG pathway analysis revealed that the changes in volatile and non-volatile metabolites induced by different processing methods were due to the effect of blanching on glutathione and fatty acid metabolism. These findings provide a comprehensive understanding of how post-harvest processing affects the quality of dried roses.

Formation of key aroma-active and off-flavor components in concentrated peach puree

Non-volatiles offer some insight into the formation of aroma-active components in peach puree (PP), but more depth investigation is still needed. Formation pathways of key aroma-active and off-flavor components in PP during thermal concentration (PP + C) and sterilization (PP + C + S) are unclear. Therefore, GC-O-MS combined with UPLC-MS/MS was used to identify the volatile and nonvolatile components and their formation pathways. Among the 36 aroma-active compounds, the contents of γ-decalactone, hexyl acetate, leaf acetate, hexanal, and 1-hexanol (odor activity value ≥ 1) decreased by 46 %, 100 %, 100 %, 92 %, and 100 % between PP and PP + C + S, causing the weakening of "green" and "fruity" attributes. Off-flavor components including 1-octen-3-one, isobutyric acid, isothiazole, and isovaleric acid were identified during thermal processing. 1-Octen-3-one content increased by 75 % from PP to PP + C + S through linolenic acid metabolism, which contributed to "cooked"; the formation of isobutyric and isovaleric acids, isothiazole, resulted in the enhancement of "sour/rancid" via serine and leucine metabolism.

Effect of Different Drying Methods on the Quality of Oudemansiella raphanipes

In this study, we used fresh Oudemansiella raphanipes as raw materials and pre-treated through hot air drying (HD), infrared radiation drying (ID), and vacuum freeze drying (VD) to investigate the effects of different drying methods on the rehydration rate, appearance quality, microstructure, and volatile flavor components of the dried products, as well as to determine the physicochemical properties and bioactivities of the polysaccharides in the dried O. raphanipes. The results showed that the VD O. raphanipes had the highest rehydration rate and the least shrinkage in appearance, and it better maintained the original color of the gills, but their aroma was not as strong as that of the HD samples. The scanning electron microscopy results indicate that VD maintains a good porous structure in the tissue, while HD and ID exhibit varying degrees of shrinkage and collapse. Seventy-five common volatile substances were detected in the three dried samples, mainly alkanes, alcohols, and esters. The polysaccharides (PS-H, PS-I, and PS-V) extracted from the dried samples of these three species of O. raphanipes had similar infrared spectral features, indicating that their structures are basically consistent. The highest yield was obtained for PS-V, and the polysaccharide content and glucuronic acid content of PS-I were higher than those of the remaining two polysaccharides. In addition, PS-V also showed better antioxidant activity and inhibitory activity against α-glucosidase as well as α-amylase. In conclusion, among the above three drying methods, the quality of O. raphanipes obtained by vacuum freeze drying is the best, and this experiment provides a theoretical basis for the selection of drying methods for O. raphanipes.

Effect of constant and variable temperature drying processes on drying characteristics, quality, and volatile profile of rose petals in infrared-assisted spouted bed drying

The edible rose (Rosa Crimson Glory) petals were dried using infrared-assisted spouted bed drying technology. The effects of different drying temperature conditions (30, 35, 40, 45, and 50°C, as well as stepped heating drying [SHD] and stepped cooling drying) on the drying characteristics, physicochemical properties, antioxidant capacity, and changes in volatile flavor compounds of the rose petals were investigated. The results showed that the drying time was shortened with increasing drying temperature. Both variable temperature drying processes gave the shortest drying times. Optimal color retention of rose petals was achieved at a constant temperature of 40°C and SHD. Increased drying temperature resulted in higher water-soluble polysaccharide content in the dried rose petals, whereas lower temperatures facilitated anthocyanin preservation. The variable temperature drying processes favored the retention of water-soluble polysaccharides in rose petals, but not anthocyanins. Regarding antioxidant capacity, the samples dried at 40°C and those subjected to the two variable temperature drying processes performed better. This study also analyzed the differences in volatile flavor compounds of rose petals dried under different drying conditions. It was found that the majority of volatile flavor compounds in the rose petals dried by SHD exhibited higher content levels than the other drying conditions. Therefore, considering a thorough evaluation of all relevant factors, it was clear that utilizing the SHD process was the most efficient method for obtaining the best quality rose petals overall.

Unveiling the Aromas and Sensory Evaluation of Hakko Sobacha: A New Functional Non-Dairy Probiotic Fermented Drink

At the dawn of a food transition encouraging the consumption of healthy and sustainable non-dairy probiotic products, the development of a fermented functional drink based on Sobacha is considered. Sobacha is an infusion of roasted buckwheat seeds widely consumed in Asian countries for its health benefits. As fermentation improves the nutritional and organoleptic status of grains, the mixed fermentation process involved in the development of kombucha beverages (fermented sweet tea) is conducted by inoculating a symbiotic culture of bacteria and yeasts into the transposable matrix (Sobacha instead of tea). Sobacha, a healthy pseudo-cereal matrix with promising aromas, could be fermented to potentially develop an innovative drink, named "Hakko Sobacha". This neologism would reveal the fermented character of the infusion, Hakko meaning fermented in Japanese. Considering the beverage characterization, the kinetics of the volatile organic compound syntheses were determined using stir-bar sorptive extraction followed by gas chromatography coupled to mass spectrometry analysis. Odor-active compounds were theoretically calculated to estimate the flavor composition. Finally, sensory analyses highlighted the appreciation and preferences of the consumer towards the beverages. The fermentative yield differences observed between the two buckwheat concentration modalities tested seemed to be correlated with the sugar and nutrient levels available from the starch (buckwheat) matrix. Having characterized Hakko Sobacha, this study proposed the possibility of developing new beverages by monitoring the fermentative process. This should enable improved control and enhancement of their sensorial properties, which could in turn lead to greater customer acceptability.

Influence of different pre-treatments on flavor quality of freeze-dried carrots mediated by carotenoids and metabolites during 120-day storage

Changes in carotenoids and volatiles (including β-carotene-metabolites) of freeze-dried carrots (FDC) treated by thermal/nonthermal-ultrasound (40 KHz, 10 min) and ascorbic (2%, w/v)-CaCl₂ (1%, w/v) solution ((H)UAA-CaCl₂) during a 120-day storage period were investigated. The results of HS-SPME/GC-MS showed that caryophyllene was the dominant volatile compound (70.80-275.74 µg/g, d.b) in FDC, and 144 volatile compounds were detected in 6 samples. Besides, 23 volatile compounds were significantly correlated with β-carotene content (p < 0.05), and β-carotene degraded to off-flavor compounds (β-ionone: 22.85-117.26 µg/g, β-cyclocitral: 0-113.84 µg/g and dihydroactindiolide: 4.04-128.37 µg/g) that had adverse effects on FDC flavor. However, UAA-CaCl₂ effectively preserved the total carotenoid content (793.37 µg/g), and HUAA-CaCl₂ reduced the off-odors (such as β-cyclocitral and isothymol) formation at the end of storage. These results indicated that (H)UAA-CaCl₂ treatments were conducive to the maintenance of carotenoids and the flavor quality of FDC.

Characterization of Aroma Active Compound Production during Kombucha Fermentation: Towards the Control of Sensory Profiles

Since the sensorial profile is the cornerstone for the development of kombucha as a beverage with mass market appeal, advanced analytical tools are needed to gain a better understanding of the kinetics of aromatic compounds during the fermentation process to control the sensory profiles of the drink. The kinetics of volatile organic compounds (VOCs) was determined using stir bar sorptive extraction-gas chromatography-mass spectrometry, and odor-active compounds were considered to estimate consumer perception. A total of 87 VOCs were detected in kombucha during the fermentation stages. The synthesis of mainly phenethyl alcohol and isoamyl alcohol probably by Saccharomyces genus led to ester formation. Moreover, the terpene synthesis occurring at the beginning of fermentation (Δ-3-carene, α-phellandrene, γ-terpinene, m- and p-cymene) could be related to yeast activity as well. Principal component analysis identified classes that allowed the major variability explanation, which are carboxylic acids, alcohols, and terpenes. The aromatic analysis accounted for 17 aroma-active compounds. These changes in the evolution of VOCs led to flavor variations: from citrus-floral-sweet notes (geraniol and linalool domination), and fermentation brought intense citrus-herbal-lavender-bergamot notes (α-farnesene). Finally, sweet-floral-bready-honey notes dominated the kombucha flavor (2-phenylethanol). As this study allowed to estimate kombucha sensory profiles, an insight for the development of new drinks by controlling the fermentation process was suggested. Such a methodology should allow a better control and optimization of their sensory profile, which could in turn lead to greater consumer acceptance.