Physicochemical indicators coupled with multivariate analysis for comprehensive evaluation of matcha sensory quality

Correlation analysis and modeling application from objective indicators to subjective evaluation of scented tea: A case study of rose tea

Different scented teas provide various choices for consumers from appearance, aroma, flavor and others. Aiming to define advantages and market positions of different scented teas and promote optimization of market structure, characteristics for scented tea favored by consumers and outstanding attributes of different scented teas should be clarified. Rose tea was taken as study object. Sensory evaluation and consumer acceptance were investigated. GC-MS and HPLC fingerprints were established. Physicochemical characteristics were determined. RGB integration analysis was inventively proposed for correlation analysis. The volatile compounds with spicy, green or herbal odor as camphene, β-phenethyl acetate, eugenol, and physicochemical parameters as antioxidant capacity, reducing sugar content, pH showed positive correlation with popular sensory properties. Six models for consumer preference by objective description were built through GA-SVR (accuracy = 1), and APP was developed. The research mode of scented tea has been successfully established to study multiple subjective characteristics with measurable objective parameters.

The application of untargeted metabolomics coupled with chemometrics for the analysis of agitation effects on the sensory profiles of matcha tea

In the study, the effects of agitating parameters (different agitating rates and time) on the aroma and taste profiles of matcha tea were systematically investigated by the combination of untargeted metabolomics and chemometrics. The aroma profiles of matcha tea agitated at low rates (500 rpm) and for 30 s were more richness than that agitated with other parameters by sensory analysis and gas chromatography-ion mobility spectrometry. The key aroma compounds contributed to the sensory differences of matcha tea agitated at different rates and time were analyzed by gas chromatography-mass spectrometry and partial least square-discriminate analysis (PLS-DA), which were further verified by the triangle test. Thereinto, 2,4-decadienal associated with the sweet, brown and seaweed aroma significantly affected the aroma profiles of matcha tea with different agitating rates and time. The levels of bitterness and astringency were also higher in matcha tea with low agitating rates and time by sensory evaluation, which were attributed to the variations of phenolic compounds. Flavonol glycosides, gallic acid and (-)-gallocatechin were determined the key compound to the taste differences of matcha tea with different agitating parameters by the analysis of PLS-DA based on the results of high performance liquid chromatography and the sensory verification. And flavonol glycosides were mainly contributed to the bitterness and astringency, and gallic acid and (-)-gallocatechin influenced the umami and sweetness of matcha tea. Consequently, agitation has the potential to affect the sensory profiles of matcha tea by changing aroma and taste substances.

Rapid Color Quality Evaluation of Needle-Shaped Green Tea Using Computer Vision System and Machine Learning Models

Color characteristics are a crucial indicator of green tea quality, particularly in needle-shaped green tea, and are predominantly evaluated through subjective sensory analysis. Thus, the necessity arises for an objective, precise, and efficient assessment methodology. In this study, 885 images from 157 samples, obtained through computer vision technology, were used to predict sensory evaluation results based on the color features of the images. Three machine learning methods, Random Forest (RF), Support Vector Machine (SVM) and Decision Tree-based AdaBoost (DT-AdaBoost), were carried out to construct the color quality evaluation model. Notably, the DT-Adaboost model shows significant potential for application in evaluating tea quality, with a correct discrimination rate (CDR) of 98.50% and a relative percent deviation (RPD) of 14.827 in the 266 samples used to verify the accuracy of the model. This result indicates that the integration of computer vision with machine learning models presents an effective approach for assessing the color quality of needle-shaped green tea.

Combined toxicity of abamectin and carbendazim on enzymatic and transcriptional levels in the soil-earthworm microcosm

To reveal the toxicological mechanisms of pesticide mixtures on soil organisms, this study concentrated on evaluating enzymatic activity and gene expression changes in the earthworm Eisenia fetida (Savigny 1826). Despite being frequently exposed to multiple pesticides, including the common combination of abamectin (ABA) and carbendazim (CAR), environmental organisms have primarily been studied for the effects of individual pesticides. Acute toxicity results exhibited that the combination of ABA and CAR caused a synergistic impact on E. fetida. The levels of MDA, ROS, T-SOD, and caspase3 demonstrated a significant increase across most individual and combined groups, indicating the induction of oxidative stress and cell death. Additionally, the expression of three genes (hsp70, gst, and crt) exhibited a significant decrease following exposure to individual pesticides and their combinations, pointing toward cellular damage and impaired detoxification function. In contrast, a noteworthy increase in ann expression was observed after exposure to both individual pesticides and their mixtures, suggesting the stimulation of reproductive capacity in E. fetida. The present findings contributed to a more comprehensive understanding of the potential toxicity mechanisms of the ABA and CAR mixture, specifically on oxidative stress, cell death, detoxification dysfunction, and reproductive capacity in earthworms. Collectively, these data offered valuable toxicological insights into the combined effects of pesticides on soil organisms, enhancing our understanding of the underlying risks associated with the coexistence of different pesticides in natural soil environments.

Presenting a Multispectral Image Sensor for Quantification of Total Polyphenols in Low-Temperature Stressed Tomato Seedlings Using Hyperspectral Imaging

Hyperspectral imaging was used to predict the total polyphenol content in low-temperature stressed tomato seedlings for the development of a multispectral image sensor. The spectral data with a full width at half maximum (FWHM) of 5 nm were merged to obtain FWHMs of 10 nm, 25 nm, and 50 nm using a commercialized bandpass filter. Using the permutation importance method and regression coefficients, we developed the least absolute shrinkage and selection operator (Lasso) regression models by setting the band number to ≥11, ≤10, and ≤5 for each FWHM. The regression model using 56 bands with an FWHM of 5 nm resulted in an R2 of 0.71, an RMSE of 3.99 mg/g, and an RE of 9.04%, whereas the model developed using the spectral data of only 5 bands with a FWHM of 25 nm (at 519.5 nm, 620.1 nm, 660.3 nm, 719.8 nm, and 980.3 nm) provided an R2 of 0.62, an RMSE of 4.54 mg/g, and an RE of 10.3%. These results show that a multispectral image sensor can be developed to predict the total polyphenol content of tomato seedlings subjected to low-temperature stress, paving the way for energy saving and low-temperature stress damage prevention in vegetable seedling production.

Flavor characterization of Citri Reticulatae Pericarpium (Citrus reticulata 'Chachiensis') with different aging years via sensory and metabolomic approaches

Guangchenpi (GCP), which is the peel of Citrus reticulata 'Chachiensis', is widely used as an herbal medicine, tea and food ingredient in southeast Asia. Prolonging its aging process results in a more pleasant flavor and increases its profitability. Through the integration of sensory evaluation with flavoromic analysis approaches, we evaluated the correlation between the flavor attributes and the profiles of the volatiles and flavonoids of GCP with various aging years. Notably, d-limonene, γ-terpinene, dimethyl anthranilate and α-phellandrene were the characteristic aroma compounds of GCP. Besides, α-phellandrene and nonanal were decisive for consumers' perception of GCP aging time due to changes of their odor activity values (OAVs). The flavor attributes of GCP tea liquid enhanced with the extension of aging time, and limonene-1,2-diol was identified as an important flavor enhancer. Combined with machine learning models, key flavor-related metabolites could be developed as efficient biomarkers for aging years to prevent GCP adulteration.

Comparative Analysis of the Nutritional Quality of Zizania latifolia Cultivars Harvested in Different Growing Seasons

Zizania latifolia (Z. latifolia) is a popular aquatic vegetable with various nutrients in south China, but little is known about its cultivars and growing seasons in terms of the nutritional components. This work aims to characterize the nutrients of five Z. latifolia cultivars in different growing seasons. The results showed that Z. latifolia samples differed in terms of chemical parameters, which were significantly affected by variety, growing season, and their interaction. Zhejiao No. 8, harvested in the autumn, stood out with the highest levels of vitamin C. Tangxiajiao and Zhejiao No. 1 contained the highest values of total soluble solids, reducing sugar, soluble proteins, and amino acids. Significant differences were observed between the autumn Z. latifolia and spring samples; the former were of higher quality than the latter based on hierarchical clustering analysis and principal component analysis. Moreover, total amino acids (TAA) and glutamic acid (GLU) were selected as the key indicators for Z. latifolia comprehensive quality by multiple linear regression analysis. This study provides essential information on Z. latifolia quality characteristics corresponding to cultivars and growing seasons, which lays the foundation for promoting the quality improvement of Z. latifolia scientifically.

Estimating the sensory-associated metabolites profiling of matcha based on PDO attributes as elucidated by NIRS and MS approaches

Matcha has been globally valued by consumers for its distinctive fragrance and flavor since ancient times. Currently, the protected designation of origin (PDO) certified matcha, characterized by unique sensory attributes, has garnered renewed interest from consumers and the industry. Given the challenges associated with assessing sensory perceptions, the origin of PDO-certified matcha samples from Guizhou was determined using NIRS and LC-MS platforms. Notably, the accuracy of our established attribute models, based on informative wavelengths selected by the CARS-PLS method, exceeds 0.9 for five sensory attributes, particularly the particle homogeneity attribute (with a validation correlation coefficient of 0.9668). Moreover, an LC-MS method was utilized to analyze non-target matcha metabolites to identify the primary flavor compounds associated with each flavor attribute and to pinpoint the key constituents responsible for variations in grade and flavor intensity. Additionally, high three-way intercorrelations between descriptive sensory attributes, metabolites, and the selected informative wavelengths were observed through network analysis, with correlation coefficients calculated to quantify these relationships. In this research, the integration of matcha chemical composition and sensory panel data was utilized to develop predictive models for assessing the flavor profile of matcha based on its chemical properties.

A review on matcha: Chemical composition, health benefits, with insights on its quality control by applying chemometrics and multi-omics

This review discussed the origin, manufacturing process, chemical composition, factors affecting quality and health benefits of matcha (Camellia sinensis), and the application of chemometrics and multi-omics in the science of matcha. The discussion primarily distinguishes between matcha and regular green tea with processing and compositional factors, and demonstrates beneficial health effects of consuming matcha. Preferred Reporting Items for Systematic Reviews and Meta-Analyses was adopted to search for relevant information in this review. Boolean operators were incorporated to explore related sources in various databases. Notably, climate, cultivar, maturity of tea leaves, grinding process and brewing temperature impact on the overall quality of matcha. Besides, sufficient shading prior to harvesting significantly increases the contents of theanine and chlorophyll in the tea leaves. Furthermore, the ground whole tea leaf powder delivers matcha with the greatest benefits to the consumers. The health promoting benefits of matcha are mainly contributed by its micro-nutrients and the antioxidative phytochemicals, specifically epigallocatechin-gallate, theanine and caffeine. Collectively, the chemical composition of matcha affected its quality and health benefits significantly. To this end, more studies are required to elucidate the biological mechanisms of these compounds for human health. Chemometrics and multi-omics technologies are useful to fill up the research gaps identified in this review.

Monitoring chlorophyll changes during Tencha processing using portable near-infrared spectroscopy

Monitoring chlorophyll during Tencha (the raw ingredient for matcha) processing is critical for determining the matcha's color and quality. The purpose of this study is to explore the mechanism of chlorophyll changes during Tencha processing and evaluate the viability of predicting its content by a portable near-infrared (NIR) spectrometer. The Tencha samples' spectral data were first preprocessed using various preprocessing techniques. Subsequently, iteratively variable subset optimization (IVSO), bootstrapping soft shrinkage (BOSS), and competitive adaptive reweighted sampling (CARS) were used to optimize and build partial least square (PLS) models. The CARS-PLS models achieved the best predictive accuracy, with correlation coefficients of prediction (R_p) = 0.9204 for chlorophyll a, R_p = 0.9282 for chlorophyll b, and R_p = 0.9385 for total chlorophyll. These findings suggest that NIR spectroscopy could be used as a surrogate for immediate quantification and monitoring of chlorophyll during Tencha processing.

Application of visible-near infrared spectroscopy in tandem with multivariate analysis for the rapid evaluation of matcha physicochemical indicators

Consumer preference for matcha is heavily influenced by its physicochemical properties. The visible-near infrared (Vis-NIR) spectroscopy technology coupled with multivariate analysis was investigated for rapid and non-invasive evaluation of particle size and the ratio of tea polyphenols to free amino acids (P/F ratio) of matcha. The multivariate selection algorithms such as synergy interval (Si), variable combination population analysis (VCPA), competitive adaptive reweighted sampling (CARS), and interval combination population analysis (ICPA) were compared, and eventually, the variable selection strategy of ICPA and CARS hybridization was firstly proposed for selecting the characteristic wavelengths from Vis-NIR spectra to build partial least squares (PLS) models. Results indicated that the ICPA-CARS-PLS models achieved satisfactory performance for the evaluation of matcha particle size (Rp = 0.9376) and P/F ratio (Rp = 0.9283). Hence the rapid, effectual, and nondestructive online monitoring, Vis-NIR reflectance spectroscopy in tandem with chemometric models is significant for the industrial production of matcha.

A comprehensive review of matcha: production, food application, potential health benefits, and gastrointestinal fate of main phenolics

Matcha, a powder processed from tea leaves, has a unique green tea flavor and appealing color, in addition to many other sought after functional properties for a wide range of formulated food applications (e.g., dairy products, bakery products, and beverage). The properties of matcha are influenced by cultivation method and processing post-harvest. The transition from drinking tea infusion to eating whole leaves provides a healthy option for the delivery of functional component and tea phenolics in various food matrix. The aim of this review is to describe the physico-chemical properties of matcha, the specific requirements for tea cultivation and industrial processing. The quality of matcha mainly depends on the quality of fresh tea leaves, which is affected by preharvest factors including tea cultivar, shading treatment, and fertilization. Shading is the key measure to increase greenness, reduce bitterness and astringency, and enhance umami taste of matcha. The potential health benefits of matcha and the gastrointestinal fate of main phenolics in matcha are covered. The chemical compositions and bioactivities of fiber-bound phenolics in matcha and other plant materials are discussed. The fiber-bound phenolics are considered promising components which endow matcha with boosted bioavailability of phenolics and health benefits through modulating gut microbiota.

Identification of volatile compounds and metabolic pathway during ultrasound-assisted kombucha fermentation by HS-SPME-GC/MS combined with metabolomic analysis

The current work combines headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC/MS) with multivariate analysis fusion metabonomics for examining metabolite profile changes. The correlation with metabolic pathways during the fermentation of kombucha tea were comprehensively explored. For optimizing the fermentation process, ultrasound-assisted factors were explored. A total of 132 metabolites released by fermented kombucha were detected by HS-SPME-GC/MS. We employed the principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) to present the relationship between aroma components and fermentation time, of which the first two principal components respectively accounted for 60.3% and 6.5% of the total variance. Multivariate statistical analysis showed that during the fermentation of kombucha tea, there were significant differences in the phenotypes of metabolites in the samples, and 25 characteristic metabolites were selected as biomarkers. Leaf alcohol was first proposed as the characteristic volatile in the fermentation process of kombucha. Furthermore, we addressed the generation pathways of characteristic volatiles, their formation mechanisms, and the transformational correlation among them. Our findings provide a roadmap for future kombucha fermentation processing to enhance kombucha flavor and aroma.

Effects of Major Royal Jelly Proteins on the Immune Response and Gut Microbiota Composition in Cyclophosphamide-Treated Mice

Increasing evidence suggests that royal jelly (RJ) has exceptional biological properties, and that major royal jelly proteins (MRJPs) are the key active factors in RJ. The objective of this study was to compare the difference in the protein content between RJ and MRJPs using non-labeled, quantitative proteomics technology, and to investigate the adjustment features and mechanisms of MRJPs on murine immune functions and the composition of intestinal flora in cyclophosphamide-treated mice. Results showed that, during the process of extracting MRJPs, the ratio of the protein types in the main protein and other proteins decreased significantly, except for MRJP1 and MRJP7, which demonstrated that an enriching effect of MRJP1 and MRJP7 was present during the extraction process. Cyclophosphamide-induced mice were orally administered MRJPs. Results showed that the middle-dose group, which received 0.25 g/(kg·bw) of royal jelly main protein, demonstrated a clear impact on the development of the spleen and liver, the quantity of peripheral blood leukocytes, immunoglobulin content, immune factor level, and the proliferation ability of spleen lymphocytes. A 16S rRNA high-throughput sequencing technology analysis showed that MRJPs could improve the component and richness of intestinal flora and raise the immunity of mice. The above-mentioned results indicated that the application of MRJPs is very likely to have an advantage effect on murine immune functions.

Storage stability of texture, organoleptic, and biological properties of goat milk yogurt fermented with probiotic bacteria

Introduction

Goat milk is an attractive food due to its high nutritional values, easy digestibility and hypoallergenicity, but has an undesirable "goaty" flavor.

Methods

In this study, goat yogurt was fermented with four probiotics, respectively, including Lactobacillus acidophilus (GYA), Bifidobacterium animalis (GYB), Lactobacillus casei (GYC) and Lactobacillus plantarum (GYP), and tested for texture, organoleptic, and biological properties during a 4-week storage period at the refrigerated temperature.

Results

All goat yogurt with probiotics showed an increase on titratable acidity and a corresponding downward trend on pH value. Viable counts of L. acidophilus and L. casei were above 6 log cfu/mL at the end of the storage, which met the minimum standards for viable probiotic bacteria in yogurt specified by the Food and Agriculture Organization of United Nation (FAO). The texture and organoleptic characteristics of fermented goat milk depended on the strain and the storage period. DPPH free radical scavenging rate and ferric reducing antioxidant power activity gradually increased in all goat yogurts during the storage and yogurt with probiotic bacteria showed higher values than those of GY0.

Discussion

Among all probiotic containing goat yogurts, GYC exhibited the desirable characteristics of hardness, adhesiveness, water holding capacity, antioxidant activity during the whole storage. Furthermore, the addition of L. casei effectively weakened the goaty flavor and enhanced the overall acceptability. Thus, fermented goat milk with L. casei is optional for the development of goat milk product with satisfactory texture properties, pleasant sensory quality and high bioactivity.

The Effect of Microwave Radiation on the Green Color Loss of Green Tea Powder

Microwave radiation is one of the main heating methods for food processing, especially affecting the color quality of colorful foods. This work presents the effect of microwave radiation on the green color loss of green tea powder (GTP) by the color description (L*, a*, b*, and H_a of green tea powder, L*:whiteness/darkness, a*: redness/greenness, and b*: yellowness/blueness; H_a derived from Hunter a and b could visually describe the color space) of the Hunter color system. First, the L*, a*, and b* were determined from the GTP samples treated with various microwave powers with the change of time to investigate the kinetic of color loss. Then, the L*, a*, and b*and temperature of GTP samples with serious thickness treated with constant microwave power (700 W) for a different time were determined to study the effect of sample thickness on the color loss. Finally, the chemicals that contributed to color change in the GTP samples treated with mild, moderate, and severe radiation were analyzed. The results showed that L*, |a*| (|a*|was the absolute value of a*), b*, and H_a decreased with the power increase in microwave radiation, and their changes conformed to the first-order kinetics. The activation energies (E_a) of different thickness GTP for change of L*, a*, b*, and H_a values could be predicted with the fitting models, and E_a for 20 mm-thick GTP were approximately 1/5, 1/8, 1/8, and 1/13 of those for 4 mm-thick GTP. The color loss was mainly caused by the Mg²⁺ loss of chlorophylls and the formation of derivates under mild radiation, the degradation of chlorophylls and the formation of theaflavin from catechins under moderate radiation, and the degradation of chlorophylls and their derivates accompanied by Maillard reaction between reducing sugar and amino acids under severe radiation. The results indicate that sample thickness and radiation time are two key parameters to keeping the color of GTP in food processing and microwave pasteurization.

Characterization of Roasting Time on Sensory Quality, Color, Taste, and Nonvolatile Compounds of Yuan An Yellow Tea

Roasting is crucial for producing Yuan An yellow tea (YAYT) as it substantially affects sensory quality. However, the effect of roasting time on YAYT flavor quality is not clear. To investigate the effect of roasting time on the sensory qualities, chemical components, odor profiles, and metabolic profile of YAYTs produced with 13 min roasting, 16 min roasting, 19 min roasting, 22 min roasting, and 25 min roasting were determined. The YAYTs roasted for 22 min got higher sensory scores and better chemical qualities, such as the content of gallocatechin (GC), gallocatechin gallate (GCG), free amino acids, solutable sugar, meanwhile the lightness decreased, the hue of tea brew color (b) increased, which meant the tea brew got darker and yellower. YAYTs roasted for 22 min also increased the contents of key odorants, such as benzaldehyde, nonanal, β-cyclocitral, linalool, nerol, α-cedrol, β-ionone, limonene, 2-methylfuran, indole, and longiborneol. Moreover, non-targeted metabolomics identified up to 14 differentially expressed metabolites through pair-wise comparisons, such as flavonoids, phenolic acids, sucrose, and critical metabolites, which were the main components corresponding to YAYT roasted for 22 min. In summary, the current results provide scientific guidance for the production of high quality YAYT.

An Overview of Sensory Characterization Techniques: From Classical Descriptive Analysis to the Emergence of Novel Profiling Methods

Sensory science provides objective information about the consumer understanding of a product, the acceptance or rejection of stimuli, and the description of the emotions evoked. It is possible to answer how consumers perceive a product through discriminative and descriptive techniques. However, perception can change over time, and these fluctuations can be measured with time-intensity methods. Instrumental sensory devices and immersive techniques are gaining headway as sensory profiling techniques. The authors of this paper critically review sensory techniques from classical descriptive analysis to the emergence of novel profiling methods. Though research has been done in the creation of new sensory methods and comparison of those methods, little attention has been given to the timeline approach and its advantages and challenges. This study aimed to gather, explain, simplify, and discuss the evolution of sensory techniques.

Metabolomics Provides A Novel Interpretation of the Changes in Main Compounds during Black Tea Processing through Different Drying Methods

This study aimed to compare the effect of hot roller (HR) drying and hot air (HA) drying on the sensory evaluation, chemical quality, antioxidant activity, and metabolic profile of Yihong Congou black tea processed from E’cha NO1. The Yihong Congou black tea dried with HA obtained higher sensory scores and better chemical qualities such as the hue of tea brew color (a and b), content of theaflavins, thearubigins, water extract, free amino acids, tea polyphenol, and the ratio of polyphenol to amino acids as well as higher antioxidant capacities compared to that dried with HR. The HA drying tea increased the contents of volatile compounds that had positive correlation with sweet and flowery flavor, while the HR drying tea increased the contents of volatile compounds related to fruity flavor. Moreover, non-targeted metabolomics data indicated that the levels of most free amino acids significantly increased, while the levels of most soluble sugars reduced in the HA drying method compared to the HR drying method. The metabolic analysis was also consistent with the above results and revealed that D-ribose and gallic acid were the main characteristic metabolites of HA drying. Our results could provide a technical reference and theoretical guide to processing a high quality of Yihong Congou black tea.