Aromatic plants have been extensively used for their medicinal and culinary properties by the cosmetic, pharmaceutical, and food industries. Along with the prosperous development of the herbal industry, however, enormous amounts of solid biomass have been generated, creating an environmental hazard. Since the waste material generated during harvesting, pre-processing, or extraction may retain its nutritional value, it can be converted to compost or vermicompost. Nonetheless, the addition of herbal residues to the feedstock material may negatively influence biodegradation due to the lower nitrogen content, increased lignocellulose content, and the remaining bioactive compounds. Overall, this book chapter discusses the current challenges that herbal waste composting/vermicomposting faces, provides insights into the process optimisation, and summarises the potential beneficial effects of mature compost.

Since foodborne diseases are often considered as one of the biggest public health threats worldwide, effective preservation strategies are needed to inhibit the growth of undesirable microorganisms in food commodities. Up to now, several techniques have been adopted for the production of safe and high-quality products. Although the traditional methods can improve the reliability, safety, and shelf-life of food, some of them cannot be applied without rising health concerns. Thereby, the addition of various phytochemicals has gained much attention during the last decades, especially for meat products that may be contaminated with pathogenic and spoilage organisms. Thyme (Thymus vulgaris L.), as an important medicinal and culinary herb, is a promising source of bioactive compounds that have a great impact on the microbiological stability of meat by suppressing the undesirable microflora. However, the use of these antimicrobials is still facing difficulties due to their aromatic properties and variable efficacy against targeted species. In this paper, we provide an overview on the potential effects of thyme essential oil (EO) and thymol as bio-preservative agents in meat products. Furthermore, this paper provides insights into the limitations and current challenges of the addition of EOs and their constituents to meat commodities and suggests viable solutions that can improve the applicability of these phytochemicals.

In the past, several efforts have been made to find suitable substitutes for synthetic preservatives in meat products with fewer side effects on human health. Essential oils have gained worldwide interest due to their antimicrobial activity. The addition of these aromatic compounds to foods may be hampered by their strong sensory characteristics (taste and smell). The objective of this study was to evaluate the efficiency of five essential oils (EOs) (Ocimum basilicum L., Origanum vulgare L., Rosmarinus officinalis L., Salvia officinalis L., and Thymus vulgaris L.) against important foodborne pathogens. First, a microdilution assay was carried out to determine the minimal inhibitory concentration (MIC) of the EOs against Staphylococcus (Staph.) aureus ATCC 6538, Salmonella (S.) enterica subsp. enterica serovar Typhimurium ATCC 14028, and Escherichia (E.) coli ATCC 25922. Since the EOs inhibited the growth of these bacteria, their activity was studied in a real food matrix. The in vivo test was performed on the model of liver pâté: the homogenized and heat-treated samples were formulated with EOs at concentrations of 1 MIC and 2 MIC, inoculated with bacterial suspensions (10⁵ CFU/g), packaged under vacuum, and stored at 4 ºC for 3 days. The addition of 2 MIC of thyme and sage oils showed a significant reduction in the viable counts of E. coli, S. Typhimurium, and Staph. aureus compared to the control samples. Overall, this study demonstrated that thyme and sage EOs, as natural preservatives, had great potential to prevent the growth of important foodborne pathogens (E. coli, S. Typhimurium, and Staph. aureus) in liver pâté, but their efficiency was highly dose-dependent. However, the tested concentrations of EOs (1 MIC and 2 MIC) had an influence on the sensory characteristics of the finished products that may hinder their future applicability to improve the shelf-life of meat products. Therefore, further studies are required to clarify such an issue.