Food Hacking: Electric Fork @ YouTube.

Simon visits the inventor Hiromi Nakamura, who is researching the concept of “electric taste.” Hiromi has developed a fork and cup that zap your taste buds with electrical currents to make food taste saltier. We wanted to experience the shock ourselves.

Read more.

After searching around, it could be a galvanic current which can make things taste salty / tingle, mouth water? If you’ve had metal filing there can sometimes be issues with the different metals present.