Investigating sensory properties of seven watermelon varieties and factors impacting refreshing perception using quantitative descriptive analysis

Fresh-cut watermelon: postharvest physiology, technology, and opportunities for quality improvement

Watermelon (Citrullus lanatus L.) fruit is widely consumed for its sweetness, flavor, nutrition and health-promoting properties. It is commonly commercialized in fresh-cut format, satisfying consumer demand for freshness and convenience, but its shelf-life is limited. Despite the potential for growth in fresh-cut watermelon sales, the industry faces the challenge of maintaining quality attributes during storage. Fresh-cut processing induces a series of physiological and biochemical events that lead to alterations in sensory, nutritional and microbiological quality. A signal transduction cascade involving increases in respiration and ethylene production rates and elevated activities of cell wall and membrane-degrading enzymes compromise cellular and tissue integrity. These responses contribute to the development of quality defects like juice leakage, firmness loss and water-soaked appearance. They also drive the loss of bioactive compounds like lycopene, affecting flesh color and reducing nutritional value, ultimately culminating in consumer rejection, food losses and waste. Although great research progress has been achieved in the past decades, knowledge gaps about the physiological, biochemical and molecular bases of quality loss persist. This review article summarizes the advances in the study of physicochemical, microbiological, nutritional, and sensory changes linked to the deterioration of watermelon after processing and during storage. Different technological approaches for quality improvement and shelf-life extension are summarized: pre- and postharvest, physical, and chemical. We also discuss the advantages, disadvantages and challenges of these interventions and propose alternative directions for future research aiming to reduce qualitative and quantitative fresh-cut watermelon losses.

Co-expression of metabolites and sensory attributes through weighted correlation network analysis to explore flavor-contributing factors in various Pyrus spp. Cultivars

Flavor profiles of various Pyrus spp. cultivars exhibit significant variations, yet the underlying flavor-contributing factors remain elusive. In this investigation, a comprehensive approach encompassing metabolomics analysis, volatile fingerprint analysis, and descriptive sensory analysis was employed to elucidate the flavor disparities among Nanguoli, Korla fragrant pear, and Qiuyueli cultivars and uncover potential flavor contributor. The study comprehensively characterized the categories and concentrations of nonvolatile and volatile metabolites, and 925 metabolites were identified. Flavonoids and esters dominated the highest cumulative response, respectively. Utilizing weighted correlation network analysis (WGCNA), seven highly correlated modules were identified, yielding 407 pivotal metabolites. Further correlation analysis of the differential substances provided potential flavor constituents strongly associated with various sensory attributes; taste factors had a certain association with olfactory characteristics. Our findings demonstrated the manifestation of flavor was a result of the synergistic effect of various compounds; evaluation olfactory flavor necessitated a comprehensive consideration of taste substances.

Consumer perception of whole watermelons

There are many varieties of watermelons, providing distinct external and internal sensory attributes. This study used an online survey (n = 700) and focus groups (n = 25) to investigate consumer perception of whole watermelons. Rind color, sound of the melon, size, and price were the most important attributes for consumers when selecting a whole watermelon. Freshness was the most important whole watermelon characteristic, and watermelon freshness/quality was driven by sweetness, crispness, and juiciness. Consumers preferred seedless watermelons that had a light rind with dark green stripes, red flesh, an oval/oblong shape, firm and crisp flesh, a weight of approximately 2.2-5.5 kg, and labeling that described them as fresh, juicy, and sweet. Two consumer clusters were identified from quantitative survey data and were also representative of focus group participants: value consumers and watermelon enthusiasts. Watermelon enthusiasts were differentiated by a higher value for claims including local, product of USA, sustainably farmed, and organic. Watermelon purchase is quality driven: consumers will pay more for guaranteed sweetness and crispness. PRACTICAL APPLICATION: The ideal watermelon for all consumers is one that is dark green with stripes, is medium sized and oblong in shape, has a minimal rind-to-flesh ratio, and boasts dark, vibrant red flesh that is sweet, crisp, and juicy. All consumers want a better guarantee on watermelon quality because it is hard to predict sensory quality when selecting a melon. This study demonstrated the intrinsic and external drivers of liking for fresh watermelons and summarized a consumer watermelon purchase and consumption journey map that can guide further research and development of watermelons and provide insights on how to increase watermelon sales.

Predicting VOCs content and roasting methods of lamb shashliks using deep learning combined with chemometrics and sensory evaluation

A comparison was made between the traditional charcoal-grilled lamb shashliks (T) and four new methods, namely electric oven heating (D), electric grill heating (L), microwave heating (W), and air fryer treatment (K). Using E-nose, E-tongue, quantitative descriptive analysis (QDA), and HS-GC-IMS and HS-SPME-GC-MS, lamb shashliks prepared using various roasting methods were characterized. Results showed that QDA, E-nose, and E-tongue could differentiate lamb shashliks with different roasting methods. A total of 43 and 79 volatile organic compounds (VOCs) were identified by HS-GC-IMS and HS-SPME-GC-MS, respectively. Unsaturated aldehydes, ketones, and esters were more prevalent in samples treated with the K and L method. As a comparison to the RF, SVM, 5-layer DNN and XGBoost models, the CNN-SVM model performed best in predicting the VOC content of lamb shashliks (accuracy rate all over 0.95) and identifying various roasting methods (accuracy rate all over 0.92).

Exploring the Aroma Fingerprint of Various Chinese Pear Cultivars through Qualitative and Quantitative Analysis of Volatile Compounds Using HS-SPME and GC×GC-TOFMS

To comprehensively understand the volatile compounds and assess the aroma profiles of different types of Pyrus ussuriensis Maxim. Anli, Dongmili, Huagai, Jianbali, Jingbaili, Jinxiangshui, and Nanguoli were detected via headspace solid phase microextraction (HS-SPME) coupled with two-dimensional gas chromatography/time-of-flight mass spectrometry (GC×GC-TOFMS). The aroma composition, total aroma content, proportion and number of different aroma types, and the relative quantities of each compound were analyzed and evaluated. The results showed that 174 volatile aroma compounds were detected in various cultivars, mainly including esters, alcohols, aldehydes, and alkenes: Jinxiangshui had the highest total aroma content at 2825.59 ng/g; and Nanguoli had the highest number of aroma species detected at 108. The aroma composition and content varied among pear varieties, and the pears could be divided into three groups based on principal component analysis. Twenty-four kinds of aroma scents were detected; among them, fruit and aliphatic were the main fragrance types. The proportions of aroma types also varied among different varieties, visually and quantitatively displaying changes of the whole aroma of the different varieties of pears brought by the changes in aroma composition. This study contributes to further research on volatile compound analysis, and provides useful data for the improvement of fruit sensory quality and breeding work.

Comparative Analysis of the Quality in Ripe Fruits of Cuiguan Pear from Different Regions

The Cuiguan pear is called "June snow" and the skin is thin; the meat is crisp and juicy; the taste is thick and fresh; and the juice is rich and sweet. In this study, the volatile organic compounds and the sensory and physicochemical parameters of the Cuiguan pear from four different regions of China (Sichuan (SC), Shangdong (SD), Chongming (CM), Zhuanghang (ZH)) were assessed. The highest differences in the physicochemical parameters were observed between four regions. The volatile fingerprints of GC-IMS showed great differences in the volatile of the Cuiguan pear, which suggested that the aroma of pears could be largely impacted by origin areas. (E)-ethyl-2-hexenoate can be used to distinguish between the 'CM' and pears from other regions. High contents of 2-heptanone, 1-pentanol, 1-butanol, 3-methylbutanol, butyl 2-methylbutanoate, heptyl acetate and butyl acetate were observed in the 'SD'. Dimethyl trisulfide, 6-methyl-5-hepten-2-one, 3-hydroxy-2-butanone, 1-penten-3-one, beta-pinene, γ-terpinene, propanal, (e)-2-pentenal, (e)-2-heptenal, 1-pentanol and 3-methyl-1-pentanol were primarily contained in the 'ZH'. Principal component analysis showed that there was very good discrimination based on the information obtained from GC-IMS for four samples. These findings were in agreement with the sensory analysis. In the opinion of the respondents to the consumer test, 'ZH' resulted in the most appreciated sample based on the average scores of the acceptability. This study provides some reference for the development and utilization of the Cuiguan pear.

Evaluation of the intensity of cigarette odors based on the perception of consumers

INTRODUCTION

We evaluated the tobacco odor intensity of cigarettes based on a large consumer panel and explored the differences of odor intensity perception based on sex, age and smoking habits.

METHODS

The perceived intensity of tobacco odor of cigarettes was evaluated using a consumer group method. A consumer panel of 240 volunteers (80 smokers, 80 ex-smokers and 80 non-smokers) was asked to smell eleven unlit cigarettes and then report their tobacco odor intensity in a specific questionnaire.

RESULTS

All volunteers clearly determined the presence of tobacco odor in all cigarettes. There is a general decrease of the perceived odor intensity with age, for both males and females. Moreover, tobacco odor perceived intensity, among all volunteer groups (smokers, non-smokers, ex-smokers), was higher for females than for males. Non-smokers declared the highest perceived tobacco odor intensities, followed by ex-smokers and smokers, who recorded the lowest perceived odor intensity. Perceived odor intensity decreased with age, with a higher rate for females compared to males, but independently of the smoking habits.

CONCLUSIONS

Regular and untrained consumers confirmed that a tobacco odor of different intensity can be perceived during the smelling of unlit cigarettes. This perceived intensity depends on sex, age and smoking habits.

Examining the consumer view of refreshing perception, relevant fruits, vegetables, soft drinks, and beers, and consumer age and gender segmentations

Consumer perspective of refreshing perception is underexplored, despite it being an emotional attribute to describe foods, beverages, hygiene products, and household items. An online survey (N = 1518) was designed to collect consumer insight into the importance of refreshing, the definition and factors related to it, and the identification of refreshing fruits, vegetables, and drinks. Nearly all participants (99.8%) cited that they have had the need to consume a food or beverage to feel refreshed, and 76.3% cited that they need this at least once per day. The factors most associated with refreshing were thirst-quenching (84.1%), temperature (86.2%), and cooling taste (86.0%). Water (86.6%), watermelons (80.8%), and cucumbers (83.5%) were the beverages/foods most frequently specified as refreshing. A second survey (N = 1050) examined refreshing perception specifically related to beer consumption and associated flavor. Beer was rated highly refreshing by 75.5% of participants, affirming its refreshing reputation. Refreshing perceived from beer was most associated with cool temperature (95.4%), flavor of the beer (88.6%), lightened mood (87.1%), and thirst-quenching (49.0%). Beers with crisp/clean flavors (87.3%) and citrus flavors (35.7%-51.7%) were most frequently specified as refreshing. There were no gender differences in the definition of refreshing and associated thirst-quenching and cold, although age differences in defining beer refreshing were significant (p ≤ .05). There were significant gender and age differences in types of refreshing vegetables, soft drinks, beer flavors, and varieties. The study provided consumer insight into refreshing perception and the gained knowledge could be used in new product design.

Consumer Hedonic Ratings and Associated Sensory Characteristics and Emotional Responses to Fourteen Pecan Varieties Grown in Texas

Pecan is one of the top five most widely consumed tree nuts, and pecan nut quality is a major factor for consideration in breeding better pecan cultivars for use by producers. However, the pecan industry faces a hurdle to evaluate its nutmeat taste, and there has so far been limited evaluation of consumer attitudes toward pecan nutmeat. This study aimed to investigate the consumer (n = 198) hedonic rating, diagnostic sensory attribute intensity, and emotional response for 14 pecan samples, consisting of native/seedling and improved varieties. The results showed all kernels received positive hedonic scores (>5, 9-point hedonic scale) for overall acceptance and the acceptability of size, interior color, typical-pecan flavor, and raw-nut flavor. The primary sensory attributes (intensities > 5.0, 0−10 line scale) were typical-pecan and raw-nut flavors, followed by buttery flavor, sweetness, and astringency. Kernel off-flavors were not perceived in general. For 20 emotion-associated terms, the intensity of the satiating effect was medium, while the energizing effect was lower. The major emotional responses were healthy, satisfied, and comfort, followed by calm, interested, premium, and relaxed. Kernel variety difference was significant (p ≤ 0.05) for all these measured variables. Consumer overall acceptance toward pecan kernels was driven by the acceptability of flavor and interior color, flavor intensities, no off-flavors, and positive emotional responses; kernel size was not an impactful factor. The six most preferred varieties were 86TX2-1.5, Pawnee, Barton, 1997-09-0012, 1991-01-0026, and Harris Super. This study is the first to use consumer input to assess nut quality and consumption preference and will be foundational to ongoing breeding programs to develop new pecan cultivars that will better meet consumer preferences and expectations, and therefore will be accepted by the processing industry and growers.

Free Amino Acids and Volatile Aroma Compounds in Watermelon Rind, Flesh, and Three Rind-Flesh Juices

Watermelon rind is treated as agricultural waste, causing biomass loss and environmental issues. This study aimed to identify free amino acids and volatiles in watermelon rind, flesh, and rind-flesh juice blends with ratios of 10%, 20%, and 30%. Among the 16 free amino acids quantified, watermelon rind alone contained higher total amino acids (165 mg/100 g fresh weight) compared to flesh alone (146 mg/100 g). The rind had significantly higher (1.5×) and dominant amounts of citrulline and arginine (61.4 and 53.8 mg/100 g, respectively) than flesh. The rind, however, contained significantly lower amounts of essential amino acids. Volatile analysis showed that watermelon rind total volatiles (peak area) comprised only 15% of the flesh volatiles. Of the 126 volatiles identified, the rind alone contained 77 compounds; 56 of these presented in all five samples. Aldehydes and alcohols were most prevalent, accounting for >80% of the total volatiles in all samples. Nine-carbon aldehyde and alcohol compounds dominated both the flesh and rind, though the rind lacked the diversity of other aldehydes, alcohols, ketones, terpenes, terpenoids, esters and lactones that were more abundant in the watermelon flesh. Watermelon rind was characterized by the major aroma compounds above their thresholds, including 17 aldehydes and six unsaturated nine-carbon alcohols. This study demonstrated the potential for rind as a food or beverage supplement due to its key features such as concentrated citrulline and arginine, relatively low odor intensity, and valuable volatiles associated with fresh, green, cucumber-like aromas.

Genetic Analysis of Fruit Quality Traits in Sweet Watermelon (Citrullus lanatus var. lanatus): A Review

Fruit quality traits of sweet watermelon (Citrullus lanatus var. lanatus) are crucial for new product development and commercialization. Sweet watermelon fruit quality traits are affected by the compositions of phytochemical compounds, phytohormones, and fruit flesh firmness which are affected by genes, the growing environment and their interaction. These compositions determine fruit ripening, eating quality, and postharvest shelf-life. Knowledge of the genetic profile and analyses of quality traits in watermelon is vital to develop improved cultivars with enhanced nutritional compositions, consumer-preferred traits, and extended storage life. This review aims to present the opportunities and progress made on the genetic analysis of fruit quality traits in watermelon as a guide for quality breeding based on economic and end-user attributes. The first section of the review highlights the genetic mechanisms involved in the biosynthesis of phytochemical compounds (i.e., sugars, carotenoids, amino acids, organic acids, and volatile compounds), phytohormones (i.e., ethylene and abscisic acid) and fruit flesh structural components (i.e., cellulose, hemicellulose, and pectin) elicited during watermelon fruit development and ripening. The second section pinpoints the progress on the development of molecular markers and quantitative trait loci (QTL) analysis for phytochemical compounds, phytohormones and fruit quality attributes. The review presents gene-editing technology and innovations associated with fruit quality traits for selection and accelerated cultivar development. Finally, the paper discussed gene actions conditioning fruit ripening in citron watermelon (C. lanatus var. citroides [L. H. Bailey] Mansf. ex Greb.) as reference genetic resources to guide current and future breeding. Information presented in this review is useful for watermelon variety design, product profiling and development to serve the diverse value chains of the crop.

Watermelon Rind and Flesh Volatile Profiles and Cultivar Difference

Watermelon rind is treated as agricultural waste and commonly discarded, causing environmental issues and biomass loss. This study aimed to identify volatile profiles of watermelon rind and flesh and their cultivar difference. Volatiles were analyzed using solid-phase microextraction–gas chromatography–mass spectrometry (SPME-GC-MS). A total of 132 volatiles were identified, including aldehydes, alcohols, ketones, terpenes/terpenoids, esters, lactones, acids, and sulfides. In both rind and flesh, the most dominant compounds in numbers and abundance (peak area) were aldehydes and alcohols, which accounted 94–96% of the total volatile abundance in the rind and 85–87% in the flesh. Total volatile in watermelon rind was only 28–58% of the corresponding flesh samples. Both rind and flesh shared nine-carbon aldehydes and alcohols, though the rind lacked additional diversity. Volatile difference between rind and flesh was greater than the difference among cultivars, although volatiles in the rind could be two times difference between Fascination and other three watermelons (Captivation, Exclamation, and Excursion). This study provides the first-hand knowledge regarding watermelon rind volatile profiles and cultivar difference and shows the potential use of rind in food or beverages due to its naturally contained nine-carbon compounds.

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.

Exploring Plant Performance, Fruit Physicochemical Characteristics, Volatile Profiles, and Sensory Properties of Day-Neutral and Short-Day Strawberry Cultivars Grown in Texas

To assist increasing annual acreage of Texas-grown (U.S.A.) strawberries, it is essential to select cultivars with excellent plant and fruit quality characteristics suitable to the diverse environments. This study assessed multiple traits of 10 strawberry cultivars grown under high tunnels. A significant difference (p ≤ 0.05) was observed for all traits, which possessed a wide variability of metabolites. Plant analysis (number of live plants, plant vigor, and harvest yield) indicated that the yield ranged from 226 to 431 g/plant, positively correlated to plant vigor. Fruit physicochemical characteristic analysis, including red color (absorbance at 500 nm) and taste-associated indicators [°Brix, titratable acidity (TA), and total soluble solids (TSS)/TA], showed that °Brix and TSS/TA ranged from 8.0 to 12.9 and from 9.1 to 15.3, respectively. More than 300 volatiles were identified using solid-phase microextraction-gas chromatography-mass spectrometry, and total volatiles varied 1.5 times with high variance of individual compounds between cultivars. Descriptive sensory analysis indicated that strawberry flavor was positively associated with sensory attributes of sweetness, jammy, fruity, buttery, fresh, and creamy while negatively related to bitterness, astringency, and sourness. Partial least squares regression indicated that strawberry flavor was highly correlated with sweet taste and volatile composition. No specific relationship between these traits and day-neutral or June-bearing varieties was identified. Ideal cultivars for Texas growing conditions with superior and balanced flavor qualities were Albion, Sweet Charlie, Camarosa, Camino Real, and Chandler.

Consumer acceptance of watermelon flesh-rind blends and the effect of rind on refreshing perception

Watermelon flesh is widely consumed for its appealing flavor and refreshing properties, though the rind of the fruit also has traits of interest, especially its nutritional benefits. This study aimed to determine if watermelon flesh blended with 0%, 10%, 20%, and 30% w/w rind could appeal to consumers, and the effect of rind on the refreshing perception was investigated. Consumers (n = 102) evaluated the liking and intensity levels of overall flavor, sweet, sour, green, watermelon flavor, and refreshing quality along with questions regarding the texture, off flavors, and aftertaste of the samples. The addition of rind was acceptable up to the 20% rind level, which was given an overall rating above the midpoint of the scale, while the 10% and 0% rind samples did not differ significantly (P < 0.001). Overall liking most strongly correlated with sweet liking (r = 0.78, P < 0.001) and watermelon flavor liking (r = 0.77, P < 0.001). Refreshing liking most strongly correlated with watermelon flavor liking (r = 0.75, P < 0.001) and decreased with addition of rind in the samples (P < 0.001). The excessive green notes, off flavors, and undesirable texture of rind decreased the hedonic and refreshing ratings of samples with 20% and 30% rind, respectively. This research demonstrated the acceptability of using up to 20% rind to supplement watermelon juice blends and results suggested that watermelon flavor drives the refreshing perception. PRACTICAL APPLICATION: These findings exhibit the diversity in consumer preferences for watermelon flesh blended with rind using a consumer test. The refreshing properties of watermelon flesh as related to sweetness and watermelon flavor, along with the flavor and mouthfeel attributes contributed by watermelon rind, are highlighted. Manufacturers of fruit-based beverages can apply this research to inform development of refreshing products, watermelon flavored products, or products that utilize rind waste.

Metabolome and Transcriptome Integration Reveals Insights Into Flavor Formation of 'Crimson' Watermelon Flesh During Fruit Development

Metabolites have been reported as the main factor that influences the fruit flavor of watermelon. But the comprehensive study on the dynamics of metabolites during the development of watermelon fruit is not up-to-date. In this study, metabolome and transcriptome datasets of 'Crimson' watermelon fruit at four key developmental stages were generated. A total of 517 metabolites were detected by ultrahigh-performance liquid chromatography-electrospray ionization-tandem mass spectrometry and gas chromatography-solid-phase microextraction-mass spectrometry. Meanwhile, by K-means clustering analysis, the total differentially expressed genes were clustered in six classes. Integrating transcriptome and metabolome data revealed similar expression trends of sugars and genes involved in the glycolytic pathway, providing molecular insights into the formation of taste during fruit development. Furthermore, through coexpression analysis, we identified five differentially expressed ADH (alcohol dehydrogenase) genes (Cla97C01G013600, Cla97C05G089700, Cla97C01G001290, Cla97C05G095170, and Cla97C06G118330), which were found to be closely related to C9 alcohols/aldehydes, providing information for the formation of fruit aroma. Our findings establish a metabolic profile during watermelon fruit development and provide insights into flavor formation.