I use pectic enzyme to break fruit down pre- and during-fermentation, as well as to clear pectic haze post fermentation. I have not read anybody here recommend using epsom salts in winemaking, but maybe someone else has experience with it.
"In wine, a small dose of magnesium sulphate acts as a yeast nutrient, providing the necessary food for a strong yeast growth. The dose rate is half teaspoon per 5 litres of wine togetherwith the yeast. It can also be used together with other nutrients to ensure a healthy yeast colony."