**5. Discussion**

After analyzing the different GMs at each stage of the supply chain, the following section discusses the results to extend the current findings from the literature. The analyzed data from the interviews will be compared with the literature to develop propositions that provide new insights into sustainability governance in food supply chains.

The analysis of the interviews shows that contracts and certificates are popular GMs to increase sustainability. In the examined supply chain, the producer and the actors of the following stages use contracts to increase the economic sustainability of their business relationships, while certificates are used to ensure ecological and social sustainability standards. At the raw material production stage, in addition to the economic aspects, also ecological and social requirements are included in contracts and informal agreements (e.g., cultivation methods or energy management). The inclusion of ecological and social standards in contracts and agreements fosters the certification of all farmers at the raw material production stage. The interview partners emphasize that the implementation of certificates is very complex and expensive. Especially for individual farmers, it is difficult to become certified on their own. Often, small farms lack the necessary financial and human resources to implement the certification requirements [45]. Therefore, the pooling of capacities (e.g., [46]) in cooperatives is observed in the case study at the raw material production level. Training provided by the cooperative to the farms, as well as the sharing of technical equipment, enables the certification of all farms in the cooperative. The cooperative supports the farmers in implementing the certificates' standards and controls them itself, e.g., through audits. To ensure that the cooperative's strong commitment to helping certify farms is profitable, the cooperative needs a warrant for the long-term compliance of the farms with the required minimum sustainability standards and thus the retaining of the certification. Therefore, the cooperative uses contracts and informal agreements with the farms, which specify the compliance with all required sustainability standards in the long-term. Contracts urge farmers to comply with social and environmental sustainability standards (e.g., fair and safe working conditions, and limited use of pesticides), as there can be, for example, penalties for non-compliance. On the other side, contracts allow the cooperative to be more committed during the certification process, as the effort promises long-term benefits. Thus, through the use of contracts, sustainability standards can be jointly implemented (e.g., ecological cultivation methods, and improvement of working conditions), which enable the certification of the supply chain.
