Task: Categorize the tweet's emotional expression, classifying it as either 'neutral or no emotion' or as one or more of the specified emotions (anger, anticipation, disgust, fear, joy, love, optimism, pessimism, sadness, surprise, trust) that reflect the tweeter's state of mind.
Tweet: Did you know apples turn brown when a enzyme called polyphenol oxidase reacts with oxygen! Well I do #dull #applefacts 🤓🍏
This tweet contains emotions: 
joy, optimism