The potential correlation between bacterial diversity and the characteristic volatile flavour of traditional dry sausages from Northeast China

Highlights

• The pdredominant phyla were Firmicutes and Proteobacteria in traditional dry sausage.

• A total of 120 volatile compounds were detected in the five traditional sausages.

• Five core bacteria improved the formation of volatile compounds in dry sausage.

Abstract

The objective of this study was to explore the correlation between bacterial communities and volatile compounds in traditional dry sausages from different regions in Northeast China. The bacterial community structure of dry sausages from five different regions as determined by high-throughput sequencing technology demonstrated that Firmicutes and Proteobacteria were the predominant phyla; Lactobacillus, Staphylococcus, Leuconostoc, Lactococcus and Weissella were the predominant genera; and Staphylococcus xylosus, Lactobacillus sakei, Weissella hellenica, Leuconostoc citreum, Lactococcus raffinolactis and Lactobacillus plantarum were the predominant species. Meanwhile, a total of 120 volatile compounds were detected in sausages from five different regions and mainly included alcohols, acids, aldehydes, ketones, esters and terpenes. Furthermore, the potential correlations between the core bacteria and major volatile compounds (64) were explored based on Spearman's correlation analysis. Positive correlations were found between W. hellenica, Lb. sakei, Lactococcus lactis, Lactobacillus alimentarius, Lb. plantarum and carboxylic acids and alcohols. Lc. lactis, Lb. alimentarius and Lb. plantarum were associated with the production of most esters, aldehydes and ketones. This study provides a deep insight into the relationship between the bacterial community and the volatile flavour profile of dry sausages, which may be helpful for the production of fermented dry sausages.

Introduction

Dry sausage is consumed throughout the northeast region of China and has been popular and well-known for hundreds of years due to its unique flavour and texture. In China, dry sausage is a typical representative of the traditional fermented meat product with local characteristics, which is usually prepared from September to November (Chen et al., 2016). Generally, lean pork and pork back fat were minced, mixed with the salts, sugars, nitrite, wine and spices, and then stuffed into natural pig intestine casings. The sausage is stored in an opened chamber for 10–15 d for air-dying and spontaneous fermentation according to artisanal technology (Hu et al., 2019). During preparation, the sausage is usually exposed to an open environment, in which a number of microorganisms participate in this process, particularly bacteria derived from the raw materials and the environment (Liu et al., 2019; Aquilanti et al., 2016). Many studies have proven that the bacterial communities in fermented sausage play significant roles in the quality characteristics of sausage.

With the development of DNA sequencing technology and bioinformatic analysis methods, high-throughput sequencing (HTS) approaches have been widely and successfully applied to determine the bacterial community structure and composition present in meats. According to the report of Chen et al. (2019), Lactobacillus and Staphylococcus were the dominant bacteria responsible for the quality of Harbin dry sausages. Moreover, Wang et al. (2018) found that Staphylococcus and Weissella were the dominant bacteria in Chinese dry-cured sausage. As we expected, Lactobacillus and Staphylococcus are the core bacterial genera in fermented meats. Furthermore, some researchers have focused on the structures of the specie communities in fermented meats to obtain more information on specific bacteria. Leuconostoc mesenteroides and Lactobacillus sakei are the predominant species in Croatia dry fermented sausages (Zgomba Maksimovic et al., 2018). Lb. sakei, Pediococcus acidilactici and Weissella thailandensis are the predominant species in Spanish-type chorizo (Juárez-Castelán et al., 2019). It is believed that these core bacterial species have a critical effect on the quality of fermented sausage and that their metabolites can provide a characteristic flavour profile (Cao et al., 2017; He et al., 2019).

Recently, numerous studies have been conducted to characterize the comprehensive correlation between the microbiota and flavours of various fermented foods, such as liquor, vinegar, cheese, paocai and da-jiang (Huang et al., 2018; Wu et al., 2017, 2018; Zheng et al., 2018; Xiao et al., 2018). These studies provide crucial information for us to understand the structure and succession of the microbial community and flavours of traditional fermented foods. However, due to the complexity of spontaneous fermentation and the lack of a data mining strategy, the complex correlations between the core bacteria and characteristic flavours of fermented meat products remain unclear.

In this study, the composition and diversity of bacterial communities were analysed using an HTS approach, and volatile compounds were detected via headspace solid-phase microextraction combined with gas chromatographymass spectrometry (HS-SPME-GC-MS). Meanwhile, physical and microbial analyses of dry sausage, including the moisture content, water activity (aw), pH and bacterial population, were conducted. Furthermore, the potential correlations between core bacteria and major volatile compounds were explored and the core bacteria responsible for volatile flavour were determined in dry sausages. This study may be helpful for standardizing the industrial production of fermented dry sausages and improving the quality consistency.