In recent years, consumers' emotional responses have been found to be an important complement to sensory and hedonic evaluations for the prediction of food choice and consumption behaviour. Given this trend, it is essential that the influence of contextual variables on emotion are investigated. The present study contributes to the discussion with an investigation of the effect of social context on implicit emotional responses to food images. 87 participants (56 female, 31 male) viewed food images of varying acceptability either alone, with a stranger, or with a friend. Subjective liking ratings were measured using a labelled affective magnitude scale, and facial muscle activity from zygomaticus major (contracted during smiling), corrugator supercilii (contracted during frowning) and levator labii superioris (contracted during nose wrinkling) were measured with an EMG recording system. Controlling for individual differences in facial expressivity and food image acceptability using linear mixed models, it was found that the presence of a co-acting stranger facilitated muscle activity indicative of a disgust response, increased the strength of relationship between muscle activity and subjective liking ratings, and led to lower subjective liking overall. No differences in muscle activity or subjective liking were found between subjects who participated alone and with a co-acting friend. This suggests that the influence of social context is complex, where the relationship between the subject and the social environment can impact both hedonic and emotional evaluations of food stimuli. These findings indicate that facial EMG can be a useful dynamic and implicit measure of emotion in consumer research, but it is critical to consider the social context of the testing environment.