Differences in the “Egumi” Taste of Moso-Bamboo Shoots
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Furusawa et al. J Wood Sci (2021) 67:35 https://doi.org/10.1186/s10086-021-01969-5 Journal of Wood Science NOTE Open Access Diferences in the “egumi” taste of moso-bamboo shoots: research using chemical analysis and two types of taste sensors Yuka Furusawa1,2*, Hitoshi Nakamura2 and Tatsuya Ashitani1,3 Abstract We conducted our research with the aim of determining whether the “egumi” taste of moso-bamboo shoots difers depending on the production area and how the “egumi” taste of bamboo shoots from Yamagata Prefecture, which is near the northern limit of cultivation, difers. The investigation was conducted using conventional chemical analy- sis methods to quantitatively evaluate the presence and content of homogentisic acid and oxalic acid in bamboo shoots from diferent regions. In addition, qualitative evaluation, for which chemical analysis alone is insufcient, was conducted using taste sensors, which have rarely been used. As a result, chemical analysis showed that homogentisic acid was not identifed among the two substances considered to be major components of egumi taste, while oxalic acid was identifed in all samples. Therefore, it is highly likely that oxalic acid is responsible for the “egumi” taste in this study. In addition, qualitative analysis using taste sensors revealed that there is a diference in “egumi” taste depending on the origin of the bamboo shoot. It was suggested that bamboo shoots from Yamagata Prefecture, near the north- ern limit of cultivation, had a stronger “egumi” taste than those from Kyoto and Fukuoka Prefectures. Keywords: Moso-bamboo, Bamboo shoots, Place of origin, “Egumi” taste Introduction income during the long period of timber production [3], Moso-bamboo (Phyllostachys edulis) is the largest spe- and bamboo shoots are produced widely throughout cies of bamboo in Japan and was introduced in the sev- Japan. Te production of bamboo shoots in Japan is done enteenth century for food, having edible young shoots mainly south of the Kansai region, which accounts for (bamboo shoots), and for materials [1]. In recent years, 89.5% of the national total [4], and the Tohoku region is the number of bamboo forests that are not being used only 1.4%, owing to its proximity to the northern cultiva- properly has been increasing due to a decrease in the use tion limit. In 2019, the production volume in Yamagata of bamboo materials, and in order to solve these prob- Prefecture was the largest in the Tohoku region, 193.7 lems, new applications are being developed, such as the tons [4]. production of rayon, the development of technology for In Yamagata Prefecture, the supply of locally collected the production of cellulose nanofbers, a new material bamboo shoots has not kept up with demand. Currently, made from bamboo, and products using the extracted liq- these locally collected bamboo shoots are mainly con- uid [2]. On the other hand, bamboo shoot production is sumed within the prefecture [5], but there is a move- a valuable income sources because it provides an annual ment to brand bamboo shoots in each production area, and producers are highly interested in this “value added” branding. Tere are several factors to be considered when *Correspondence: [email protected] diferentiating bamboo shoots from other regions, such 1 The United Graduate School of Agricultural Sciences, Iwate University, as shipping time, size, quality, and functional ingredi- 3-18 Ueda, Morioka, Iwate 020-0066, Japan Full list of author information is available at the end of the article ents. Te taste is also an important unique characteristic. © The Author(s) 2021. 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J Wood Sci (2021) 67:35 Page 2 of 9 Bamboo shoot growers sensibly feel that the taste of bam- from the inland region, one in Yamanobe Town and one boo shoots, especially “egumi” taste, varies depending on in Asahi Town. To compare the results with those of the production area where they are grown, and there is a other prefectures, one site in Kyoto Prefecture and one strong interest in the diference between regions within site in Fukuoka Prefecture were selected from the top the same prefecture and the diference between bamboo production regions, which are south of western Japan [4]. shoots produced in snow-covered areas near the north- Tree bamboo shoots were collected from each site. ern limit of cultivation and those produced in other Because the developmental time for bamboo shoots prefectures. varies from region to region, the collection period was To date, studies on the taste of moso-bamboo have approximately 10 days after the frst bamboo shoot was been based mostly on chemical analyses of related sub- confrmed at each site, which ranged from early to late stances [6–10], and the major components respon- May in 2017. Te size of the bamboo shoots collected sible for the “egumi” taste have been reported to be was standardized to the Shonai area’s standard M (600– homogentisic acid and oxalic acid [6, 11]. However, 1000 g) for fresh food shipments [5]. Te bamboo shoots while chemical analyses may show quantitative difer- were collected from the two locations outside of the pre- ences in taste-related substances, they are insufcient to fecture from early to mid-April in 2018, and three bam- describe qualitative diferences in detail. Tere is a huge boo shoots that met the same raw food shipping standard variety of taste-related substances, and their interac- M (600–1000 g) used for those collected within the pre- tions cannot be ascertained through chemical analyses fecture were selected. [12–14]. Terefore, in general, the taste of food is judged Fresh edible bamboo shoots collected in the prefec- by sensory testing, but this testing is also problematic. ture are distributed mainly through in-prefecture mar- It requires qualifed inspectors, who are biased by their ket shipments and direct sales, with the shortest time own opinions and physical conditions. In addition, there from collection to sale being approximately one day, and are diferences in what constitutes an “appealing” taste to they are rarely kept refrigerated during market manage- consumers from various cultures and traditions [12, 15, ment or sales [5]. Terefore, assuming similar distribu- 16]. For this reason, in recent years, objective taste sen- tion conditions, bamboo shoots were transported to the sors have been used to complement chemical analyses Yamagata Prefecture Forestry Research and Training and sensory evaluations in quality diferentiation and Center within 3 h of collection, stored in a well-ventilated new product development [13, 14, 16–18]. In the feld of area out of direct sunlight until 24 h after collection, and forestry, the taste of nameko mushrooms was quantifed then fxed by freezing. Specimens collected in Kyoto and to objectively evaluate their taste [19]. Fukuoka prefectures were also transported and stored In this study, we focused on the taste of bamboo shoots, under conditions similar to those in Yamagata Prefec- which growers are interested in. In particular, we aimed ture, and they were transported by refrigerated vehicle to clarify whether the “egumi” taste difers depending on to the Yamagata Prefecture Forest Research and Training the production area, and how the “egumi” taste of bam- Center within 2 days. Upon arrival, the specimens were boo shoots produced in Yamagata Prefecture, which is immediately frozen and fxed. close to the northern limit of cultivation, difers from the All the frozen bamboo shoots were freeze-dried for taste of bamboo shoots produced in other regions. To approximately 3 days and used as samples. Te freeze- clarify this point, we quantitatively evaluated the pres- drying does not greatly alter the processing methods, ence and content of homogentisic acid and oxalic acid in and the component levels before drying are mostly main- bamboo shoots grown in and outside of the prefecture tained [20–22]. Because there is no change in favor that using conventional chemical analysis. In addition, quali- would cause the food to lose its original characteristics, tative evaluation, which is insufcient for chemical analy- there is no efect on sensory testing or taste sensor and sis, was conducted using taste sensors, which have rarely chemical analyses [20]. been used in the past. Analysis of the “egumi” taste of bamboo shoots by region. Materials and methods Material collection and sample preparation Chemical analysis Bamboo shoots were collected from eight locations Homogentisic acid and oxalic acid, which are consid- (Fig. 1), six of which were located in Yamagata Prefec- ered to be the main components of “egumi” taste, were ture. Four were collected from the Shonai region, which analyzed in one sample from Shonai area in Yamagata is the main production area in the prefecture, one in Yuza Prefecture (Yuza Town), one sample from inland area in Town, one in Mikawa Town, and two in Tsuruoka City Yamagata Prefecture (Asahi Town), and one sample from (Sanze and Haguro), while the other two were collected outside the prefecture (Fukuoka Prefecture).