Phytochemicals and Aroma Compounds Content of Crabapple (Malus tribolata C.K. Schneid.) Genotypes in Kahramanmaraş Province

Crabapple (Malus tribolata C.K. Schneid.), which one of the rare wild fruit trees in Turkey. This study was carried out to determine the aroma compounds, phenolic compound, antioxidant capacity and some fruit properties of fruits obtained from 2 different crabapple genotypes. The amount of phenolic substance was done by Folin-Ciocalteu method; antioxidant analysis was done using DPPH technique. With respect to antioxidant capacities, the highest value (70.12%) was determined in 46 EL 01 genotype. We found that 46 EL 01 genotype had the highest total phenolic content (839.13 mg/100 g). Determination of volatile compounds that play a major role in fruit quality using the HS-SPME/GC/MS technique, total of 37 aroma compound, namely 7 alcohols, 2 terpenes, 5 aldehydes, 17 esters, 1 ketone, 3 acids and 2 other compounds, were found in two different crabapple genotypes. Total aroma compounds in 46 EL 01 and 46 EL 02 genotypes were calculated as 101.78 μg/L and 102.26 μg/L, respectively. As a result, it has been determined that crabapple, which is a wild fruit, has high phenolic and antioxidant contents and also has many aroma compounds.

Aroma Profile of Arabica Coffee Based on Ohmic Fermentation

Aromatic components contained in coffee are the important components. Several technologies can be used to improve the aroma quality of coffee, for example with ohmic technology. This study established a specialty coffee processing system focused on ohmic-based fermentation technology. The aim of this study was to identify the aroma compound in coffee that fermented by ohmic technology. The SPME method by gas chromatography-mass spectrometry is used in this study. The temperatures (30, 35, and 40°C) and fermentation time were set for this study (2, 6, 12, and 18 h). The results of the sensory test of sample coffee from Indonesia with specification of areas of origins Enrekang and Gowa in comparison with a sample of coffee from Japan can conclude that the panelist provided a rating profile liking the sample coffee from Japan, but the overall results of the quantitative descriptive analysis (QDA) of the second sample are similar or nonsignificantly different. Compound pyrazine identified in GC-MS is earthy odor which has a correlation with the results of sensory taste QDA on sample coffee from Japan.

Improving the Transglycosylation Activity of α-glucosidase From Xanthomonas Campestris Through Semi-rational Design for the Synthesis of Ethyl Vanillin-α-glucoside

The α-glucosidase (EC 3.2.1.20) Agl2 produced by Xanthomonas campestris shows high α-glucosyl transfer activity toward alcoholic and phenolic hydroxyl groups. Ethyl vanillin-α-glucoside, a precursor-aroma compound with improved water solubility and thermal stability, can be synthesized through the transglycosylation of ethyl vanillin by Agl2. However, its low ethyl vanillin-α-glucoside yield and ability to hydrolyze ethyl vanillin-α-glucoside limits for industrial applications. Rational design and site-directed mutagenesis were employed to generate three variants of X. campestris α-glucosidase: L145I, S272T and L145I/S272T, which displayed improved transglycosylation activity toward EV The ethyl vanillin-α-glucoside yield of L145I/S272T is the highest and is up to yield 52.41%. Besides, L145I/S272T also remarkably diminished the hydrolysis activity toward the transglycosylation product EVG compared to Agl2. Our rational design based the catalytic mechanism of the α-glucosidase reaction proved to be effective for producing mutants with improved the ratio of transglycosylation/hydrolysis of α-glucosidase, which provides an important theoretical basis for further research on the reaction mechanism of α-glucosidase.

Enhancement of the Aroma Compound 2-Acetyl-1-pyrroline in Thai Jasmine Rice (Oryza sativa) by Rhizobacteria under Salt Stress

Thai jasmine rice (Oryza sativa L. KDML105), particularly from inland salt-affected areas in Thailand, is both domestically and globally valued for its unique aroma and high grain quality. The key aroma compound, 2-acetyl-1-pyrroline (2AP), has undergone a gradual degradation due to anthropogenic soil salinization driven by excessive chemical input and climate change. Here, we propose a cheaper and an ecofriendly solution to improve the 2AP levels, based on the application of plant growth-promoting rhizobacteria (PGPR). In the present study, nine PGPR isolates from rice rhizosphere were investigated for the 2AP production in liquid culture and the promotion potential for 2AP content in KDML105 rice seedlings under four NaCl concentrations (0, 50, 100, and 150 mM NaCl). The inoculation of 2AP-producing rhizobacteria resulted in an increase in 2AP content in rice seedling leaves with the maximum enhancement from Sinomonas sp. ORF15-23 at 50 mM NaCl (19.6 µg·kg−1), corresponding to a 90.2% increase as compared to the control. Scanning electron microscopy confirmed the colonization of Sinomonas sp. ORF15-23 in the roots of salinity-stressed KDML105 seedlings. Our results provide evidence that Sinomonas sp. ORF15-23 could be a promising PGPR isolate in promoting aroma level of Thai jasmine rice KDML105 under salt stress.

Oenococcus oeni Lifestyle Modulates Wine Volatilome and Malolactic Fermentation Outcome

In this study, nine Oenococcus oeni strains were tested for their ability to adhere to polystyrene using mMRS and wine as culture media. Moreover, planktonic and biofilm-detached cells were investigated for their influence on malic acid degradation kinetics and aroma compound production. Three strains were able to adhere on polystyrene plates in a strain-dependent way. In particular, MALOBACT-T1 and ISO359 strains mainly grew as planktonic cells, while the ISO360 strain was found prevalent in sessile state. The strain-dependent adhesion ability was confirmed by confocal laser scanning microscopy. Planktonic and biofilm detached cells showed a different metabolism. In fact, biofilm-detached cells had a better malic acid degradation kinetic and influenced the aroma composition of resulting wines, acting on the final concentration of esters, higher alcohols, and organic acids. Oenococcus oeni in biofilm lifestyle seems to be a suitable tool to improve malolactic fermentation outcome, and to contribute to wine aroma. The industrial-scale application of this strategy should be implemented to develop novel wine styles.

Optimization of Fermentation Conditions for Production of Hungarian Sour Cherry Spirit Using Response Surface Methodology

Pálinka is a traditional fruit spirit and a kind of gastronomic heritage in Hungary. In Pálinka production, fermentation is one of the most important processes affecting the quality and yield of spirits. Based on single-factor and three-factor influence level tests by following the Plackett–Burman design, the fermentation process from sour cherry juice concentrate and Saccharomyces cerevisiae by using Response Surface Methodology (RSM) coupled with the central composite rotatable design was investigated to optimize fermentation conditions through three variables in a defined range of temperature (1525 °C), pH (2.753.75), and total soluble solid (1830 °Brix). After eight fermentation days, production yields of alcohol and volatile compounds were a maximum of 9.02% v/v and 337.37 mg/L at an optimized temperature of 24.71 °C, pH of 3.25, and total soluble solid of 22.49 Brix. The GC-FID analysis results showed 1-propanol, 2-methyl-1-propanol, 2-methyl-1-butanol, 3-methyl-1-butanol, and ethyl acetate were considered the major aroma compound in the cherry spirits. These results provided important information in serving the basic to develop standard fruit spirits production from sour cherry.

Aromatic Higher Alcohols in Wine: Implication on Aroma and Palate Attributes during Chardonnay Aging

The higher alcohols 2-phenylethanol, tryptophol, and tyrosol are a group of yeast-derived compounds that have been shown to affect the aroma and flavour of fermented beverages. Five variants of the industrial wine strain AWRI796, previously isolated due to their elevated production of the ‘rose-like aroma’ compound 2-phenylethanol, were characterised during pilot-scale fermentation of a Chardonnay juice. We show that these variants not only increase the concentration of 2-phenylethanol but also modulate the formation of the higher alcohols tryptophol, tyrosol, and methionol, as well as other volatile sulfur compounds derived from methionine, highlighting the connections between yeast nitrogen and sulfur metabolism during fermentation. We also investigate the development of these compounds during wine storage, focusing on the sulfonation of tryptophol. Finally, the sensory properties of wines produced using these strains were quantified at two time points, unravelling differences produced by biologically modulating higher alcohols and the dynamic changes in wine flavour over aging.