  In recent years, many recommender systems have utilized textual data for
topic extraction to enhance interpretability. However, our findings reveal a
noticeable deficiency in the coherence of keywords within topics, resulting in
low explainability of the model. This paper introduces a novel approach called
entropy regularization to address the issue, leading to more interpretable
topics extracted from recommender systems, while ensuring that the performance
of the primary task stays competitively strong. The effectiveness of the
strategy is validated through experiments on a variation of the probabilistic
matrix factorization model that utilizes textual data to extract item
embeddings. The experiment results show a significant improvement in topic
coherence, which is quantified by cosine similarity on word embeddings.
