Analysis of the taste quality of specialty cold region berries based on non-targeted metabolomics

Berries have been one of the most popular fruits with the high nutritional value and processing prospects. A variety of berries with strong cold resistance are also produced in the northeast of China. These berries share the unique regional features, strong cold resistance, high nutritional value, and are rich in various active functions. A series of berry products have been formed in recent years. But it is limited to the acceptance of the initial processing of berry products, because of its their comprehensive quality, such as color, aroma, and taste under the low level of mechanization. Among them, the taste is one of the important indicators to evaluate the quality of fruit, which is closely related to the quality of processed products and the acceptance of consumers. In this study, ultra-high-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS/MS) and Gaschromatography-mass spectrometry (GC-MS) techniques were employed to investigate the taste features and composition of the four typical berries from cold regions, including Vaccinium uliginosum L., Lonicera cearulea L., Rubus idaeus L., and Ribes nigrum L.. The non-volatile and volatile substances of these berries were screened and then identified. Furthermore, electronic tongue analysis and sensory evaluation were conducted to obtain the overall fuzzy comprehensive scores of taste quality. Factor analysis was then performed. The results show that the alcohols, aldehydes, and hydrocarbons were the main volatile flavor substances in cranberry. There was the a high relative content of alcohols, acids, and esters in blackcurrant. The prominent relative content of ketones and acids in raspberry was induced the outstanding flavor features easy to distinguish. The volatile flavor substances of indigo fruit were mainly alcohols and esters, which were more balanced, compared with the rest berries. While there was no outstanding aroma. The findings revealed that Vaccinium uliginosum L. had a sugar-acid ratio of 4.41, and the characteristic volatile substances were α-terpinol and benzaldehyde, with the highest acid taste response from the electronic tongue. Ribes nigrum L. had a sugar-acid ratio of 3.80 and the characteristic volatile substances were phenylethanol and acetic acid, with the a relatively balanced taste response. Lonicera cearulea L. had a sugar-acid ratio of 3.37 and the highest total phenol content of (3.79±0.17) mg/g gallic acid equivalent content. Its characteristic volatile substances were n-hexene-alcohol and 3-hexene-1-alcohol, indicating the highest salt and umami taste response. Rubus idaeus L. had a sugar-to-acid ratio of 8.19 and the characteristic volatile substances were acetic acid and α-violone, with the highest sweet and bitter taste response. From the perspective of acceptability, the highest comprehensive score was found in Rubus idaeus L. While tThe comprehensive score was ranked in the descending order of the Lonicera cearulea L., Vaccinium uliginosum L., and Ribes nigrum L. The sensory evaluation correlation analysis showed that sour taste, fruit flavor, aftertaste, and aftertaste had a great influence on the berry selection. Screening, identification, and statistical analysis demonstrated that there were ten compounds of the non-volatile substances, including tagose, lactic acid, aloxalulose, oxalic acid, citric acid, aspartic acid, alizarin, 6α-mannobiose, sucrose, and isoquercetin. The overall fuzzy comprehensive scores of taste sensory decreased in the descending order of Rubus idaeus L., Lonicera cearulea L., Vaccinium uliginosum L., and Ribes nigrum L. The factor analysis indicated that the taste composition scores increased in the descending order of Ribes nigrum L., Lonicera cearulea L., Vaccinium uliginosum L., and Rubus idaeus L., indicating that the higher the score of flavor substance composition was, the lower the fuzzy comprehensive score was. These findings can provide a theoretical foundation to developfor developing the high-quality products using the four cold-region berries. At the same time, the taste regulation was considered to increase the added value of berry foods for better utilization in cold areas.