Free and Glycosidically Bound Volatile Compounds in Okinawan Pineapple (Ananas comosus)

Abstract

Fruit plants produce various volatile compounds that emit distinct aroma characteristics and contribute to their flavor qualities. However, some of these substances, especially hydroxyl-group molecules, are in non-volatile glycosylated forms. This study aimed to determine free and glycosidically bound volatile compounds in three Okinawan pineapple cultivars (‘N67-10’, ‘Yugafu’, and ‘Yonekura’). The free volatile components of squashed pineapple juice were analyzed using solid-phase microextraction (SPME)–arrow-gas chromatography–flame ionization detection/mass spectrometry (GC-FID/MS). The glycosides were collected through solid-phase extraction, hydrolyzed by β-glucosidase, and the released volatile compounds were measured. The sugar moieties of the glycosides were confirmed using GC-MS, and their glycoside constituents were analyzed using liquid chromatography (LC)-MS. Okinawan pineapple varied in its content and composition of free volatile components, which were predominantly comprised of esters, followed by alcohols, terpenes, and ketones. Eight hydroxyl-group compounds, including chavicol, eugenol, geraniol, phenylethyl alcohol, benzyl alcohol, 2-ethyl-1-hexanol, 1-hexanol, and 3-methyl-2-butenol, were released from their glycosylated forms via enzymatic hydrolysis, wherein the amounts of most of them were greater in ‘Yonekura’ than in the other cultivars. Moreover, two glycosides, chavicol-O-β-D-glucopyranoside and eugenol-O-β-D-glucopyranoside, were identified in all the cultivars, wherein the aglycones of both glycosides could be potential odor sources of the medicinal-herbal aromas. These results provide important information regarding both volatile-aroma qualities and bounded-aroma resources in Okinawan pineapple for fresh consumption and agroindustrial processing.

Review of the Aroma Chemistry of Pineapple (Ananas comosus)

“…Large variation in lactone class of VOCs within given cultivar was also observed from fruit to fruit . High variation in the amount and composition of the identified VOCs among three different cultivars was also reported in Okinawan pineapple cultivars …”

“…The published literature on pineapple VOC analyses selected herein can be grouped into several categories based on the main objective of the study, such as studies focused on the following: Review of published information ,− Identification of VOC using instrumental analysis ,− OT, odor activity value (OAV) calculation, and odor description ,,, Effect of ripeness and maturity ,,, Effect of post-harvest storage and logistics ,,,− Influence of VOC isolation–extraction techniques ,,,,, Varieties and geographical locations ,,,− Seasons and environmental factors ,,,, Effect of processing and handling ,,− Sampling uniformity/tissue type , Self-interaction of VOCs within the fruit matrix , …”

“…All studies that investigated different pineapple varieties ,,,, describe varietal differences as a key influencing factor on the quality and quantity of the aroma patterns. Quantitative difference in total ester concentrations were observed for Tainung no.…”

“…5 High variation in the amount and composition of the identified VOCs among three different cultivars was also reported in Okinawan pineapple cultivars. 52 5.3. Tissue Type.…”

Assessment of Volatile Characteristics of Okinawan Pineapple Breeding Lines by Gas-Chromatography–Mass-Spectrometry-Based Electronic Nose Profiling and Odor Activity Value Calculation

“…Pineapple (Ananas comosus), an evergreen perennial plant of the Bromeliaceae family, is a popular fruit worldwide because of its unique flavor characteristics [1][2][3]. In Japan, the pineapple is one of the few horticultural trees that can be grown in the southernmost prefecture, Okinawa, where the subtropical soil is poor in organic matter and is strongly acidic [4,5]. The most cultivated variety in Okinawa is a Smooth Cayenne cultivar, 'N67-10', known for its large size, yellowish-white flesh, and high sugar content [5,6].…”