An Exploration of Pepino (Solanum muricatum) Flavor Compounds Using Machine Learning Combined with Metabolomics and Sensory Evaluation

Abstract

Flavor is one of the most important characteristics that directly determines the popularity of a food. Moreover, the flavor of fruits is determined by the interaction of multiple metabolic components. Pepino, an emerging horticultural crop, is popular for its unique melon-like flavor. We analyzed metabolomics data from three different pepino growing regions in Haidong, Wuwei, and Jiuquan and counted the status of sweetness, acidity, flavor, and overall liking ratings of pepino fruit in these three regions by sensory panels. The metabolomics and flavor ratings were also integrated and analyzed using statistical and machine learning models, which in turn predicted the sensory panel ratings of consumers based on the chemical composition of the fruit. The results showed that pepino fruit produced in the Jiuquan region received the highest ratings in sweetness, flavor intensity, and liking, and the results with the highest contribution based on sensory evaluation showed that nucleotides and derivatives, phenolic acids, amino acids and derivatives, saccharides, and alcohols were rated in sweetness (74.40%), acidity (51.57%), flavor (56.41%), and likability (33.73%) dominated. We employed 14 machine learning strategies trained on the discovery samples to accurately predict the outcome of sweetness, sourness, flavor, and liking in the replication samples. The Radial Sigma SVM model predicted with better accuracy than the other machine learning models. Then we used the machine learning models to determine which metabolites influenced both pepino flavor and consumer preference. A total of 27 metabolites most important for pepino flavor attributes to distinguish pepino originating from three regions were screened. Substances such as N-acetylhistamine, arginine, and caffeic acid can enhance pepino‘s flavor intensity, and metabolites such as glycerol 3-phosphate, aconitic acid, and sucrose all acted as important variables in explaining the liking preference. While glycolic acid and orthophosphate inhibit sweetness and enhance sourness, sucrose has the opposite effect. Machine learning can identify the types of metabolites that influence fruit flavor by linking metabolomics of fruit with sensory evaluation among consumers, which conduces breeders to incorporate fruit flavor as a trait earlier in the breeding process, making it possible to select and release fruit with more flavor.

Evaluation of the Attractant Effect of Solanum muricatum (Solanales: Solanaceae) on Gravid Female Adults of Zeugodacus tau (Diptera: Tephritidae) and Screening of Attractant Volatiles

“…In the past several decades, pepino melon has not been recorded as a host for Z. tau [1]. This could be because Z. tau is not distributed in the Andes of South America, which is the main area in which pepino melon was cultivated [12,13]. In recent years, the areas in which S. muricatum is extensively cultivated have come to overlap with the area in which Z. tau is distributed [1,19].…”

“…The pepino melon Solanum muricatum (Aiton) (Solanales: Solanaceae) is a perennial herbaceous horticultural species and a close relative of the tomato, native to the Andean region, and has been cultivated artificially since the Pre-Columbian era [12,13]. The ripened fruits have a light flavor, with a fragrant and sweet taste, making them suitable for consumption in desserts and as an ingredient of salads, juices, or ice cream [14,15].…”

“…It has long been recognized as an edible and medicinal fruit owing to its antioxidant, anti-tumor, antidiabetic, anti-inflammatory, and hypotensive properties [14,15]. For the past several decades, pepino melon had not been officially recognized as a host for Z. tau [1]; this could be because Z.tau was not distributed in the Andes of South America, a major area of pepino melon cultivation [12,13]. In recent years, the area used for S. muricatum cultivation in China has increased by nearly 200,000 hectares due to the crop's high edible and medicinal value [17][18][19].…”

De novo assembly of the complete mitochondrial genome of pepino (Solanum muricatum) using PacBio HiFi sequencing: insights into structure, phylogenetic implications, and RNA editing

“…In addition, pepino plants have excellent antioxidant, antidiabetic, anti-inflammatory, and anti-tumor activities [23][24][25][26][27][28][29]. Intensive research has been carried out on pepino to provide information about its abiotic and biotic stresses [30][31][32][33][34], plant photomorphogenesis [35,36], fruit aroma and flavor [37][38][39][40], genetic diversity [41,42], transcriptome [43], metabolome [40,44,45], and genome [46]. However, the dissection of biological functions of key genes for mitochondria-related traits is extremely challenging due to the absent of pepino mt genome.…”

Assessment of suitable cultivation region for Pepino (Solanum muricatum) under different climatic conditions using the MaxEnt model and adaptability in the Qinghai–Tibet plateau

“…It has been cultivated in southern China and is commonly associated with high altitudes, low relative drought, mild summers, and poor soils [ 5 ]. Generally, Pepino is eaten as a fruit, and the mature fruit has a unique fruit aroma; About melon flavor has been mentioned in the previous study, in the previous study analyzed the sensory evaluation and flavor compounds [ 5 ], evaluated the soil physical and chemical properties and its influence on metabolites [ 6 ], determine the degree of popularity and its nutrients, but also studied the light on the influence of seedling growth [ 7 ], and the influence on lateral development, mining the light response lateral transcription factor, and master the TCP gene family plays important functions in the process of regulation and control [ 8 ]. All of the above studies have provided scientific and accurate support for the deeper exploration of Pepino [ 9 ].…”