Purpose This study aims to examine the public discourse on sustainable food packaging, evaluating the main characteristics of that discourse and how risk and analytical message content influence consumer engagement. Design/methodology/approach The authors use two studies with databases built from messages posted on Twitter (now X). Study 1 explores the discourse of sustainable food packaging by conducting a content/sentiment analysis. Study 2 examines more than four million messages posted by or mentioning the world’s most relevant food companies. Hypotheses are tested through censored regression analyses. Findings The results show that plastic is the term that can better classify how we talk about sustainable food packaging. The authors also show that food packaging messages related to sustainability, compared to those not related to sustainability, are composed using more analytical language, contributing to generating greater engagement. Moreover, social network users remain skeptical about food companies, as the latter messages on packaging sustainability generate less engagement (likes + retweets) than when other users post these messages. Originality/value This study addresses important points in the public discourse on social networks about the sustainability of food packaging and its language features. First, the data are representative of the food market with posts from leading worldwide food companies. Second, identifying the hot topics of the discussion on sustainability packaging on social media provides a new perspective on how companies and society view sustainable food packaging. Third, the authors show how the source of the message moderates the impact of sustainability on engagement.