Objective Evaluation of Soy Sauce by Statistical Analysis of GC Profiles

The relationships between GC data of volatiles and sensory score of the heighest grade of soy sauce (Tokusen shoyu) were analyzed by multivariate analyses. Samples belonging to four brands could be unambiguously classified into the correct brands and the statistical distance among them suggested a close relation with sensory evaluation. The precise predictive equations for the aroma quality were calculated from GC data and sensory evaluation by multiple regression analysis. Eight principal components were extracted from 39 GC peaks as significant factors constituting soy sauce aroma. The second PC can explain 58% of the variation among total variation contained in the sensory score. Discriminant functions on the basis of the 8 PCs can clearly classify all samples.     

Volatile compounds of Soumbala, a fermented African locust bean (Parkia biglobosa) food condiment

AIMS: To determine the profile of volatile compounds responsible for the aroma of Soumbala produced spontaneously and with pure and mixed cultures of Bacillus subtilis and Bacillus pumilus. METHODS AND RESULTS: Traditional and controlled fermentation trials of African locust bean with pure and mixed starter cultures of B. subtilis (B7, B9 and B15) and B. pumilus (B10) were performed. Aroma volatiles were analysed using Likens-Nikerson method coupled with gas chromatography and mass spectrophotometry. Sensory analysis of Soumbala as well as rice dishes prepared with each type of Soumbala were carried out by 10 panellists. In total 116 compounds were identified. They included pyrazines, aldehydes, ketones, esters, alcohols, acids, alkanes, alkenes, amines, pyridines, benzenes, phenols, sulphurs, furans and other compounds. Using principal component analysis for comparison, the aroma profiles of the Soumbala samples could be separated into three groups. The sensory evaluation showed variable acceptability. However, it was noticed that Soumbala samples produced with starter cultures were scored higher than traditionally prepared Soumbala. CONCLUSIONS: Aroma volatiles and organoleptic properties of Soumbala vary according to the Bacillus isolates involved in the fermentation. SIGNIFICANCE AND IMPACT OF THE STUDY: This study contributes to the selection of Bacillus starter cultures for controlled production of Soumbala.     

Evaluation and Discrimination of Soy Sauce by Computer Analysis of Volatile Profiles

The relationships between gas chromatographic (GC) profiles and sensory data of 72 purely fermented soy sauce samples were analyzed by multiple regression analysis and principal component analysis (PCA). Prior to the analysis, GC data was transformed into 7 different modes in order to compare the fitting to a hypothetical linear model. The result from logarithmically transformed ratio of each peak to the sum of whole peaks showed the best precision of predictability for sensory score (R = 0.978). As the result of PCA, eigen values of 10 PCs were shown to be larger than 1.0 but the 5 major PCs could account for 66% of the variance in the total variance of 39 GC peaks. The first and second PCs showed great importance for aroma quality and similarity or dissimilarity in profiles of extracted PCs showed a similar trend with quality differences evaluated by sensory tests. These results showed the importance of the harmonious balance of each aroma compound to create a preferable soy sauce aroma.     

Sensory evaluation of character impact components in an apple model mixture

Food aromas generally are complex mixtures of volatiles. In the present study, we investigated the joint effects of hexyl acetate, trans-2-hexenal and 1-hexanol on the multi-attribute perception of an apple aroma. The first two substances were identified earlier as positive contributors to the apple aroma (high character impact), whereas the third component was identified as an irrelevant or negative contributor (low character impact). Aroma quality was quantified using a set of eight graphic rating scales. All three components had significant effects on the aroma profiles. These effects consist mainly of an effect of each component on the attribute that described its individual character and an effect of all three components on ratings on the main character attribute 'apple'. As expected, the high impact components increased 'apple' ratings, whereas the low character impact component decreased 'apple' ratings. Furthermore, intensity ratings on the attribute that corresponded with the odour of the low impact component were suppressed by the presence of high impact components. These results indicate that the contributions of odorants to the mixture's aroma are not linear combinations of separate odour intensities, because sensory interactions were observed. In addition, humans detect components in complex mixtures more accurately than studies on identification performance have suggested. We conclude that for an adequate assessment of the effects of multiple mixture components on changes in aroma perception, it is sufficient to employ multiple response scales measuring intensities of attributes that are distinctive with respect to the expected qualitative changes. Results of this approach should be subjected to multivariate methods of statistical analysis.     

Effect of a warm‐up sample on stabilizing the performance of untrained panelists in time–intensity evaluation

To improve the reliability of sensory evaluation, it is necessary to minimize response bias. In this study, we investigated the effect of a warm‐up sample on time–intensity evaluation of after‐flavor. Untrained panelists evaluated continuously perceived intensity of bitterness and retronasal aroma, using four types of samples (two brands of coffee beverages × two types of lids). Half of participants evaluated bitterness intensity in the first session and retronasal aroma intensity in the second session, whereas the other half evaluated them in the opposite order. Each session consisted of four trials, and we regarded the first trial sample of each session as a warm‐up. Results revealed that perceived intensity was significantly lower in the first trial than in the following trials, and that the time courses of the second, third, and fourth trials were similar except when participants evaluated bitterness intensity in the second session. In other words, the use of a warm‐up sample stabilized the performance of time–intensity evaluation of bitterness and retronasal aroma in the first session. Furthermore, no warm‐up sample was needed in the second session when participants evaluated bitterness intensity, but a warm‐up was needed when they evaluated retronasal aroma intensity.

Practical application

Based on the results of this study, we concluded that the use of a warm‐up sample stabilized performance in time–intensity evaluation of after‐flavor by untrained panelists. We proposed that in order to obtain reliable performance in time–intensity evaluation of after‐flavor, untrained panelists should be provided a training trial using warm‐up sample before staring the test trials.     

Recovery of aroma compounds from a wine-must fermentation by organophilic pervaporation

This study investigates the recovery of a wine-must aroma profile, formed by Saccharomyces cerevisiae during a muscatel wine-must fermentation, using organophilic pervaporation. Experiments were carried out along two independent, but organoleptically similar, fermentations. The wine-must samples and the aroma concentrates obtained were characterized organoleptically by a sensory panel and analytically with regard to eight major wine-must components: four alcohols; three esters; and one monoterpenic compound. Pervaporation performance was studied under fermentation conditions, and the permeate concentration, partial fluxes, and enrichment of the respective compounds were determined. The muscatel wine-must aroma profile was recovered purely and faithful to its origin between wine-must densities of 1075 and 1055 g L. At the beginning of the fermentation, too few aromas were present in the must for recovery. Toward the end of the fermentation, high ethanol concentrations in the wine-must caused a dramatic enrichment of two esters in the permeate, whereas other components investigated seemed unaffected. This shift resulted in an unbalanced aroma. In conclusion, it was shown that organophilic pervaporation can be highly suitable for the continuous recovery of very complex and delicate aromatic profiles produced during microbial fermentation. Copyright 1999 John Wiley & Sons, Inc.     

Influence of controlled inoculation of malolactic fermentation on the sensory properties of industrial cider

Given the lack of research in the traditional cider making field when compared to the efforts devoted to winemaking, this work focused on the effects of controlled inoculation of the malolactic fermentation (MLF) on the sensory properties of cider. MLF develops spontaneously in cider making at industrial level. In this work, industrial cider samples were inoculated with selected indigenous Oenococcus oeni strains and the benefits on the aroma and flavour in cider production compared to non-inoculated ciders were evaluated. Randomly amplified polymorphic DNA PCR was used to monitor strain colonization ability, outnumbering the indigenous microbiota, after completion of the alcoholic fermentation at industrial scale (20,000 l). Aroma-active compounds of experimentally inoculated ciders were analysed by HPLC and GC–MS, and sensory profiles were determined by fractioning aroma extracts using reversed-phase HPLC. Principal component analysis allowed the identification of relationships and differences among ciders with or without inoculation, including several highly appreciated commercial ones obtained under spontaneous conditions. Under controlled inoculation conditions, not only could MLF be shortened by half but, interestingly, enhancement of aroma complexity and flavour resulted in ciders enriched with a higher fruity note. In addition, important aromatic groups analysed here had not been previously described, thus affording deeper knowledge on aroma characterization of apple cider.     

一种紫斑牡丹花茶的研制及其主要香气成分分析

以紫斑牡丹(Paeonia suffruticosa var. papaveracea)花瓣为原料,采用隔离窨制,对牡丹花茶窨制过程中花坯、配花量等主要影响因子进行研究。结果表明,密闭箱桶温度21 ℃、相对湿度90%、窨制时间48 h条件下经一窨一提获得的花茶,感官评审花与茶叶的协调度高、香气高锐持久、茶汤滋味醇正鲜爽。采用气相色谱-质谱联用仪分析花茶香气成分,新鲜花瓣与茶叶配比5:1窨制48 h的花茶苯乙醇、香叶醇、橙花醇含量较高,其香气高扬、茶汤醇正鲜爽,配比2.5:1的花茶上述成分含量和感官其次,而拌和型茶品透素欠鲜爽。发酵或发酵揉捻花瓣窨制的花茶乙醇、环氧芳樟醇及高级烷烃含量较高,其主要赋香物质低于新鲜花瓣含量,渥味明显,茶汤有浊气欠鲜爽。     

Characteristic odor components of Citrus reticulata Blanco (ponkan) cold-pressed oil

Citrus reticulata Blanco (ponkan) cold-pressed oil and its oxygenated fraction were studied by analytical (GC and GC/MS) and sensory analyses. The monoterpene group was predominant, accounting for more than 89.6% (w/w), of which limonene was the most abundant (80.3%). Among the oxygenated compounds, octanal and decanal were the major ones among 12 aldehydes accounting for >1.5%; six alcohols were identified with a total concentration of >0.7%, while oxides, ketones and esters did not quantitatively or qualitatively contribute to the oil. Sniffing the ponkan cold-pressed oil and its oxygenated fraction demonstrated that octanal and decanal were the characteristic odor components of ponkan. Reconstruction of the ponkan aroma model and its sensory evaluation by a hedonic test were performed, showing that, in addition to octanal and decanal which played important roles, (R)-(+)-limonene contributed to the aroma model as a background component, making the aroma model very similar to that of the original.     

A COMPARISON OF METHODS FOR EVALUATING THE PERFORMANCE OF A TRAINED SENSORY PANEL1

Cluster analysis, consonance analysis, principal component analysis (PCA) and the GRAPES program (Schlich 1994) were compared for the evaluation of panel performance. Ten judges evaluated 25 Merlot wines for 24 color, aroma and flavor attributes. Cluster analysis grouped similar judges. PCA identified judges according to their attribute use. Consonance analysis determined a numerical index for attribute agreement and the GRAPES program compared judges in their use of the scale, reliability, discrimination and disagreement. Three of the four techniques provided a graphical representation of similarities and differences between judges. Methodologies were best used in conjunction with one another. Ultimately the application of these tools will serve to improve the quality of sensory evaluations.     

Characteristic Odor Components of Citrus reticulata Blanco (Ponkan) Cold-pressed Oil

Citrus reticulata Blanco (ponkan) cold-pressed oil and its oxygenated fraction were studied by analytical (GC and GC/MS) and sensory analyses. The monoterpene group was predominant, accounting for more than 89.6% (w/w), of which limonene was the most abundant (80.3%). Among the oxygenated compounds, octanal and decanal were the major ones among 12 aldehydes accounting for >1.5%; six alcohols were identified with a total concentration of >0.7%, while oxides, ketones and esters did not quantitatively or qualitatively contribute to the oil. Sniffing the ponkan cold-pressed oil and its oxygenated fraction demonstrated that octanal and decanal were the characteristic odor components of ponkan. Reconstruction of the ponkan aroma model and its sensory evaluation by a hedonic test were performed, showing that, in addition to octanal and decanal which played important roles, (R)-(+)-limonene contributed to the aroma model as a background component, making the aroma model very similar to that of the original.     

湘南烟区生态因素与烤烟质量的综合评价

 以湘南烟区气候、土壤等生态因素和烟叶质量状况为基础数据资料,运用模糊数学隶属函数模型对该区的气候适生性、土壤适宜性和烟叶质量可用性进行了综合评价,合理地进行了该区植烟区域的划分。结果表明：1)湘南烟区的气候适生性指数（Climate feasibility index, CFI）为(79.59%±3.96%),变幅为74.71%～83.98%;该区烟叶大田生长期气温适宜,日均温≥20 ℃持续天数较长,≥10 ℃活动积温较高,昼夜温差较小,降雨充沛,相对湿度较高,日照百分率较低。2 )湘南烟区的土壤适宜性指数（Soil feasibility index, SFI）为(43.92%±15.49%),变幅为13.32%～82.82%;该区土壤具有较强的保肥能力,有机质、氮素、速效磷及多种微量元素含量丰富,但pH值中性偏碱,全磷和钾素含量难以满足烟株需求,且交换性钙镁比值不协调,有效硫含量偏高,有效硼缺乏。3)湘南烟叶外观质量指数（Appearance quality index, AQI）和感观质量指数（Sen sory quality index, SQI）分别为（86.65%±3.29%）和（63.08%±0.74%）,烟叶成熟度较好,叶片结构疏松,香气质较好,杂气和刺激性相对较小。