Apple flavor has been linked to the composition of aroma compounds; however, the impact of varying concentrations of aroma compounds remains poorly understood. While sensory evaluation is commonly used to analyze food palatability, assessing the effect of concentration of all aroma compounds poses challenges. This study screened 174 apple genotypes for significant aroma compounds using regression models, Gas chromatography–mass spectroscopy analysis, and sensory palatability scores. Two models viz. Random Forest and XGBoost were employed to predict palatability scores, surpassing the limitations of correlation analysis. Shapley's additive explanatory value analysis identified 5-hexenol, ethyl 2-methyl butyrate, 2-methylbutyl acetate, (E,E)-α-farnesene, and (Z)-3-hexenol as key aroma compounds. In a sensory evaluation validating the effect of aroma compound concentration, the variation in (E,E)-α-farnesene concentration negatively affected sensory palatability scores. This study demonstrated a novel approach for identifying aroma compounds that impact apple flavor, providing valuable insights to enhance apple quality and palatability.
The combination of gas chromatography-olfactometry (GC-O) with sensitive instrumental methods, such as gas chromatography-mass spectrometry to analyze foods provides a powerful new approach to flavor development. Working with flavorist and customers to find aroma components that contribute to the concept of a new flavor, analytical chemists can assist flavorists in their development efforts. For example, using the GC-O method, CharmAnalysis, we have identified some new aliphatic esters, lactones and other compounds in the volatiles of white peach, grape (Kyohou), and pear (La France) that were used to build new flavor recipes. This paper will review the application of GC-O to flavor creation and report some of the structures of key aroma compounds found in foods during the development of new products.
Nakajimana (Brassica rapa L. cv. nakajimana), of the family Brassicaceae, is a traditional vegetable in Japan. Three isothiocyanates and five cyanides in the leaves of nakajimana were identified by gas chromatography (GC) and GC-mass spectrometry (GC-MS), and their kinetic changes using heat-treatment (temperature and time) were investigated. In addition, myrosinase activity of extracts prepared from fresh nakajimana leaf was determined. In crushed heat-treated leaves of nakajimana (70 °C for 30 s), formation of isothiocyanates and myrosinase activity increased, whereas formation of 1-cyano-3,4-epithiobutane and 1-cyano-4,5-epithiopentane decreased. Heat-treatment can significantly alter the content of potentially beneficial compounds in nakajimana, and ingestion of suitable isothiocyanates for human health may be better facilitated by mild boiling.
Changes in volatile compounds during early storage of an aseptic-cup (AC) coffee beverage without milk and sugar were examined. AC coffee samples were stored at 10°C for 0, 1, and 2 weeks. Retronasal aroma (RA) compounds of the AC samples were collected using a retronasal aroma simulator (RAS) coupled to a solidphase microextraction (SPME) fiber and then analyzed using gas chromatography-olfactometry (GC-O) and gas chromatography-mass spectrometry (GC-MS). The GC-O analysis detected 17 odor compounds. Changes in the compounds during 2-week storage were quantitatively analyzed using selected ion monitoring GC/MS. Statistical analyses of the peak areas showed that eight compounds decreased significantly (p < 0.05) during early storage, and that trends of the decreases differed among the compounds. Furthermore, a duo-trio test using an analytical sensory panel confirmed that the aroma of the 2-week sample was similar to that of the 0-week sample upon addition of the model flavor (composed of the eight compounds) to the 2-week sample.
Instrumental and sensory analyses were carried out on sesame-flavored dressings to identify the odorants affecting their perceived quality. The sampling of the odor-active compounds was performed by simultaneous steam distillation extraction (SDE) and solid-phase microextraction (SPME). The odor intensity and character of the compounds were evaluated and quantified using gas chromatography/olfactometry (GC/O). The GC/O and the sensory data were processed and analyzed on the basis of food kansei model. Seven perceptual factors affecting the aroma and flavor were abstracted by principal component analysis (PCA) of the sensory data. According to the percentage of contribution, the first perceptual factor of "roast and spicy" was identified as a key factor. The correlations between the odorants and the "roast and spicy" factor clarified the importance of sulfurous compounds. Four sulfurous compounds were identified as butanethiol, prenyl mercaptane, 2-methyl-3-furanthiol and dimethyl trisulfide.
To develop a ready-to-drink (RTD) milk coffee that retains the original coffee flavor, the effects of manufacturing processing conditions on retronasal-aroma (RA) odorants were investigated by gas chromatography-olfactometry (CharmAnalysis™) using an RA simulator (RAS). Twenty-nine of 33 odorants detected in the RAS effluent (RAS odorants) were identified. The detected odorants were classified into 19 odor-description groups. The total odor intensity (charm value, CMV) of all coffee RAS odorants decreased approximately 68% following pH adjustment, whereas the total CMV increased 6% to 7% following ultra-high-temperature sterilization. The total CMV ratio (about 83%) of the milk coffee produced using a new blending-after-sterilization (BAS) process without pH adjustment of the coffee was greater than that (approximately 56%) prepared using a conventional blending-before-sterilization (BBS) process with pH adjustment. In BAS-processed milk coffees, the total CMV ratio (91%) with infusion (INF)-sterilized reconstituted milk (r-milk) was greater than that (83%) of plate (PLT)-sterilized r-milk. Principal component analysis of odor-description CMVs indicated that the effect of coffee pH adjustment on odor characteristics was greater than that of sterilization, that BAS and BBS samples differed, and that BAS milk coffee prepared using INF sterilization was more similar to homemade milk coffee (blending unsterilized coffee without pH adjustment with PLT-sterilized milk) than milk coffee prepared using PLT sterilization. In conclusion, the BAS process using INF sterilization is superior for manufacturing RTD milk coffee that retains odor characteristics similar to targeted homemade milk coffee. PRACTICAL APPLICATION: Ready-to-drink milk coffee beverages produced using conventional blending-before-sterilization methods do not retain their original coffee flavor following adjustment of the pH of the coffee during manufacturing. The use of newly developed blending-after-sterilization methods, by contrast, produces ready-to-drink milk coffee with an aroma more similar to that of homemade milk coffee, as demonstrated using an analytical system for characterizing food product aromas. The blending-after-sterilization process is now being used in Japan to produce ready-to-drink milk coffee beverages.
Abstract Volatile aroma compounds of freeze-dried soluble coffee were investigated to evaluate the effects of freeze-drying temperature conditions on their intensities and aroma characteristics by employing both GC/MS and charm-analysis, which is a GC/Olfactometry (GC/O) method. The coffee solutions with 40% solid content were freeze-dried changing freezing and drying temperatures. According to the results, it was demonstrated that the compounds identified based on human olfactory sense were different from those detected by GC/MS, and that the GC/O analysis method enabled evaluation of the characteristics and intensity of each compound as well as aroma profiles under various freezing and drying temperatures. Subsequently, GC/O method was found to be effective to detect and identify the volatile compounds giving the aroma peculiar to freeze-dried coffee, and useful to obtain the fundamental information for designing the optimal aroma characteristics of final product to conform the consumer preference based on the characteristic changes in aroma affected by freeze-drying conditions. Keywords: Volatile aroma compoundsGC/O analysisFreezing and drying temperature conditionsConsumer's preference
