Free and bound volatile compounds in the Rubus coreanus fruits of different ripening stages

Abstract

The aim of the present study was to investigate the free and bound volatiles in the Rubus coreanus (RC) fruits of different ripening stages. Thirty‐seven free volatiles and 28 bound volatiles were identified in RC fruit for the first time. The contents of free (E)‐2‐hexen‐1‐ol, 1‐hexanol, 2‐heptanol, β‐myrcene, (E), (Z)‐β‐ocimene, allo‐ocimene, linalool, cosmene, α‐terpineol, methyl salicylate, eugenol, and β‐damascenone remain high, and increased with the ripening of RC fruit. The contents of 11 bound volatiles decreased during the ripening, and became lower than the contents of their free volatiles in the ripe fruit. The ripe black fruit is closely correlated to the free nonanal, sulcatone, (E)‐2‐hexen‐1‐ol, 1‐hexanol, 2‐heptanol, 1‐heptanol, 1‐nonanol, (E)‐linalool oxide (furanoid), and β‐damascenone, and bound (E)‐2‐hexen‐1‐ol and (E)‐ β‐ocimene. The ripe RC fruit is more fruity and floral than unripe fruit. The gradually hydrolyzed bound volatiles can enhance the fruity, floral, and herbaceous odors. Practical applications Rubus coreanus (RC) fruit is a functional natural fruit. Both fresh and processed Rubus coreanus fruits including jams, confitures, wine, yogurt, vinegar, and beverages, as well as ingredients in functional foods or cosmetics have been extensively consumed. However, the free and bound aroma compounds in RC fruit have not been well understood. This work illustrates the contributions of free and bound volatiles to the flavor of RC fruit.

Fruitomics: The Importance of Combining Sensory and Chemical Analyses in Assessing Cold Storage Responses of Six Peach (Prunus persica L. Batsch) Cultivars

“…Linalool has been previously identified as an abundant VOC in peach skin and flesh [ 35 ], showing a particularly low odour threshold. It was found to be essential for perception of the typical ‘fruity’, ‘floral’ flavour in peaches [ 35 ] and Chinese raspberry ( Rubus coreanus ; [ 36 ]). Although abundant here especially in ‘Big Bang’ before storage, it was negatively correlated with harmony and positively with unripe-related characters.…”

Free and Bound Aroma Compounds of Turnjujube (Hovenia acerba Lindl.) during Low Temperature Storage

“…A similar extraction procedure for free volatile compounds from Rubus coreanus fruits was followed [6]. A first group of turnjujube fruit was juiced immediately with a JYZ-E16 juicer (Joyoung Co., Ltd., Jinan, China) after collection, and subsequent groups of turnjujube fruits (second, third, and fourth) were packed in polyethylene bags, tightly sealed and stored for 7, 14, and 21 days.…”

“…The methods and instruments of GC-MS analysis used in this study were similar to our previous reports [6]. Briefly, a weak polar HP-5MS capillary column (30 m × 0.25 mm i.d × 0.25 µm) was used to separate the volatile compounds.…”

“…Among these compounds found in turnjujube juice, C4-C5 alcohol, aldehydes, and ketones were possibly formed through the enzymatic conversion of fatty acids or amino acids [15]. According to the reported generation mechanism of C6 alcohols and aldehydes, including 1-hexanol, hexanal, and (E)-2-hexenal [5,6], they were presumably generated from the reactions of unsaturated linoleic and linolenic acids catalyzed by lipoxygenase and hydroperoxydelyase.…”

“…In the precursors, volatile compounds are linked to saccharides by a glycosylated bond [3,4]. However, most free aroma compounds are easily lost, whereas some others can be enriched through biosynthesis and internal transformations during fruit processing and storage [5,6]. Therefore, both the free and bound volatile aroma compounds need to be evaluated in order to adequately appreciate fruit.…”