## 4 Discussion  
In the present study, the selected _L. plantarum_ SK15 strain showed a negative reaction that led to a low accumulation of biogenic amine in a fermentation process. There was a study of _L. plantarum_ N8 on agmatine (AGM) and PUT production using amino acid decarboxylation. Argin hydrochloride and ornithine monohydrochloride decarboxylase medium were used as detection. The result showed that _L. plantarum_ N8 strain did not produce AGM and PUT [34]. Thus, the suitable microorganism that did not produce decarboxylase was an important factor affecting the accumulation of biogenic amines. The effectiveness of _L. plantarum_ SK15 as a non-amino acid decarboxylate-producing stain was examined in the reduction of biogenic amine accumulation during fermentation of FMB. The addition and no addition of _L. plantarum_ SK15 in the FMB fermentation process was studied on the alteration of PUT and SPD, including safety and quality. In the natural fermentation process (without _L. plantarum_ SK15 as a starter culture), the PUT content of FMB was higher than FMB with _L. plantarum_ SK15. Similarly, SPD content of FMB without _L. plantarum_ SK15 was at a high level compared with the inoculated _L. plantarum_ SK15 as a starter. This proves that starter culture _L. plantarum_ SK15 could reduce the accumulation of the amines in FMB. Nowadays, the biogenic amine study has a limitation for adding starter culture in FMB from H. erinaceus. However, a few researchers exhibited other fermentation products. [PERSON] et al. [22] studied biogenic amine (PUT, CAD, and TYR) reduction by mixed starter culture of _L. plantarum_ Shanghai brewing 1.08 and Zygosaccharomyces rouxii CGMCC 3791 in pickled Chinese sauerkraut (cabbage pickles and radish pickles). The production of biogenic amines decreased during fermentation with co-culture as a starter in both sauerkraut pickles. Similarly, [PERSON] et al. [35] demonstrated that HIS content was reduced by 27.7% and 15.4% by the addition of starter Staphylococcus cxmonsu FS19 and Bacillus amyloliquefaciens FS05, respectively, and that the overall BA content was 15.9% and 12.5% less in inoculated S. carnonsu FS19 and B. amyloliquefaciens FS05, respectively, compared with the control in fish sauce product. A review of [PERSON] and [PERSON] [36] showed the same result. They studied biogenic amine formation in a salted and fermented anchovy by Staphylococcus as a starter culture. _S. xylosus_, applied as a protective culture in salted and fermented anchovy, could reduce histamine and overall amines by 18% and 16%, respectively, compared with the control. The content of PUT and SPD in FMB was gradually raised with the increasing fermentation time till the end of fermentation time in this study at 720 h. It might have occurred from proteolysis during fermentation time. As a result, the presence of free amino acid was increased, which led to the formation of biogenic amine in a fermented sample [37]. FMB samples with starter culture had lower biogenic amine contents than samples without a starter culture. The starter culture factor influenced the production of biogenic amine  
Figure 8: The change of microbial load in a fermented mushroom beverage (FMB) with and without starter culture _L. plantarum_ SK15 during fermentation time: (**a**) total bacteria count; (**b**) lactic acid bacteria (LAB). in fermented foods. A possible hypothesis explained that specific starter culture did not produce an amino acid decarboxylase enzyme, which changed the amino acid to a biogenic amine. Furthermore, the starter culture may inhibit biogenic amine forming bacteria by competition in the environment, rapid nutrient usage, depletion, or production of a bacteriocin-like inhibitory substance [36]. Analysis of acid content could indicate the safety and quality of FMB. The pH level slightly decreased during fermentation time in both FMB with and without _L. plantarum_ SK15. The acceptable pH was less than or equal to 4.3 for fermented beverages, according to Thai Community Standard Product (TCPS) [38].