The smell and odorous components of dried shiitake mushroom, Lentinula edodes II: sensory evaluation by ordinary people

This study is part of an effort to improve the quality of dried shiitake mushrooms [Lentinula edodes (Berk.) Pegler], in accordance with consumer preference, and deals with a preference survey using questionnaires combined with sensory evaluation. The smell was evaluated using powdered dried shiitake mushrooms. Age, original preference (OP), sex, sensory intensity (SI), hedonic preference (HP), and sample amount were set as parameters. About 70% of panelists liked dried shiitake mushrooms. There were significant correlations among age, OP, and SI. There was also a significant correlation between OP and HP, but no significant correlation between SI and HP. However, when the panelists were classified by OP, there was an optimal value between SI and HP for likers and neutralists. The calculated optimal concentration of dried shiitake mushrooms for likers and neutralists ranged widely. On the other hand, there was a significant negative correlation between SI and HP for dislikers, and their HP decreased according to the increase in the amount of the substance. The results showed that different concentrations of odorous components in dried shiitake mushrooms were needed to satisfy different consumer preferences.     

The smell and odorous components of dried shiitake mushroom, <Emphasis Type="Italic">Lentinula edodes</Emphasis> I: relationship between sensory evaluations and amounts of odorous components

The smell of food is one of the most important factors in assessing its quality. Concerning the smell of dried shiitake mushrooms [Lentinula edodes (Berk.) Pegler], 1,2,3,5,6-pentathiepane, commonly known as lenthionine, has been reported as a key compound. However, other compounds have not been studied sufficiently in connection with smell. From the results of sensory intensity studies and sensory evaluations of dried shiitake mushrooms, a positive significant correlation at 1% risk was observed between sensory intensity and sulfur perception. This showed that the smell of dried shiitake mushrooms was characterized by a sulfurous smell. Also, comparing the sensory intensity with the amounts of volatile components showed positive significant correlations at 1% risk between sensory intensity and three compounds: 1,2,4-trithiolane, 1,2,4,6-tetrathiepane, and lenthionine. Furthermore, significant correlations at 5% risk were obtained between the amounts of these three compounds and sensory intensity by multiple regression analysis. This showed that the smell of dried shiitake mushrooms depended on these compounds. The partial regression coefficient of 1,2,4-trithiolane was larger than those of the others, and so it was proposed that 1,2,4-trithiolane could serve as an indicator to estimate the smell of dried shiitake mushroom.     

The smell and odorous components of dried shiitake mushroom, Lentinula edodes VI: increase in odorous compounds of dried shiitake mushroom cultivated on bed logs

Odor is one of the most important characteristics affecting consumer preference for dried shiitake mushrooms [Lentinula edodes (Berk.) Pegler]. In our previous studies, we found that the odor content of commercial dried products was too weak for most people, and that the odorous compound content could be increased by adding amino acids to sawdust media. Currently, however, bed-log cultivation is used to produce fruiting bodies for dried products. The purpose of this study was to fi nd a method to increase the content of odorous compounds in dried products cultivated on bed logs. Pressure injection of amino acids from the side of the bed log was the most effi cient method, but it had some problems. Hence, a simpler and less troublesome method was developed, i.e., injecting amino acid solution from small bottles set in deep holes bored in the sides of the bed logs. In fruiting bodies cultivated on bed logs injected with amino acid solution by the improved method, the mean contents of lentinic acid, a precursor of the odorous compound lenthionine, approximately doubled compared to that in the untreated logs, although the infi ltration area of the solution injected by the improved method was smaller than that by the former method.     

The smell and odorous components of dried shiitake mushroom, <Emphasis Type="Italic">Lentinula edodes</Emphasis> IV: survey of trends in consumer preferences and changes in sensory evaluation

This study is part of an effort to improve the quality of dried shiitake mushrooms (Lentinula edodes) in accordance with consumer preference. Results are presented of a trend survey that examined the preferences of consumers using questionnaires combined with sensory evaluation. From the original preference (OP) survey, the distributions of OP divided by age class (AC) were statistically equal to the results obtained in 2000. The medians of OP for teenagers and twenties were “neutral” and “slightly like,” respectively. A firm preference change occurred between teenagers and those in their twenties. It is empirically realized that sensory intensity (SI) scores that were too high or too low led to a low hedonic preference (HP) score. The same tendency was seen for “neutralists” and “likers.” In addition, almost all distributions concerned with HP had no significant difference between 2000 and 2005; for example, that of SI divided by AC. These results showed that the preference for dried shiitake mushroom has been unaffected by the passage of the past 5 years. Dried shiitake mushrooms have been used from ancient times and for many dishes; therefore, the overall preference appears to have remained unchanged.     

The smell and odorous components of dried shiitake mushroom, Lentinula edodes V: changes in lenthionine and lentinic acid contents during the drying process

This study on dried shiitake mushroom [Lentinula edodes (Berk.) Pegler] focuses on the behavior of the aromatic lenthionine compound and its precursor, lentinic acid, during the drying process. Only a small amount of lenthionine was present after the drying process, regardless of the drying temperature or time; however, the amount increased during the rehydration process using pH 8.0 buffer. The lenthionine content after incubation in the buffer was correlated with the lentinic acid content in the dried shiitake mushroom. The lentinic acid content increased signifi cantly during the drying process at 40°C up to 4 h. The results show that the characteristic smell of dried shiitake mushroom was weak after drying, and that rehydration in a mild alkaline solution was necessary to increase the smell. The lentinic acid content of dried shiitake could serve as an indicator of the smell produced by rehydration and would be useful in screening to select odor-rich strains. Moderate heating likely caused the increase in lentinic acid content, which might be related to a reaction to heat.