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

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.

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.

Surmounting the off-flavor challenge in plant-based foods

Plant-based food products have been receiving an astronomical amount of attention recently, and their demand will most likely soar in the future. However, their unpleasant, intrinsic flavor and odor are the major obstacles limiting consumer's acceptance. These off-flavors are often described as "green," "grassy," "beany," "fatty" and "bitter." This review highlights the presence and formation of common off-flavor volatiles (aldehydes, alcohols, ketones, pyrazines, furans) and nonvolatiles (phenolics, saponins, peptides, alkaloids) from a variety of plant-based foods, including legumes (e.g. lentil, soy, pea), fruits (e.g. apple, grape, watermelon) and vegetables (e.g. carrot, potato, radish). These compounds are formed through various pathways, including lipid oxidation, ethanol fermentation and Maillard reaction (and Strecker degradation). The effect of off-flavor compounds as received by the human taste receptors, along with its possible link of bioactivity (e.g. anti-inflammatory effect), are briefly discussed on a molecular level. Generation of off-flavor compounds in plants is markedly affected by the species, cultivar, geographical location, climate conditions, farming and harvest practices. The effects of genome editing (i.e. CRISPR-Cas9), various processing technologies, such as antioxidant supplementation, enzyme treatment, extrusion, fermentation, pressure application, and different storage and packaging conditions, have been increasingly studied in recent years to mitigate the formation of off-flavors in plant foods. The information presented in this review could be useful for agricultural practitioners, fruits and vegetables industry, and meat and dairy analogue manufacturers to improve the flavor properties of plant-based foods.

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.

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.