Food2150 SAQ

Question 1

You’re hired! You have just been hired as a product developer for a company that deals primarily with strawberries. They have found that the price of fresh strawberries is falling, and they have decided to make a high-end jam product. After a wash, they are dicing the strawberries and want to refrigerate them until they are used, but they turn brown after 24 hrs; why is this happening and what is your recommendation to prevent it?

Answer 1

• strawberries have free water: available for both microbial growth & chemical reactions
• refrigeration slows rxns, but there is still significant water available
• water activity is high: approx 1
• at around 0.7 yeasts and bacteria stop growing, 0.5 chemical rxns stop, 0.3 enzymatic rxns stop
• freeze the strawberries until use, to reduce the amount of free water, and slows the growing
• add sugar: lowers water activity as it draws water out of th cells, slows rxns
• sugar may be a better solution: freezing may decrease the texture of the jam, and dilute it

Question 2

You are preparing to launch a strawberry pie for the holiday season, but you notice that once the pie is baked, the filling turns brown after cooking. Why is this happening, and how can it be avoided or minimized?

Answer 2

• undergoes caramelization; heating of reducing and non-reducing sugars in absence of amine-containing compounds
• or maillard rxn: reducing sugar and amino acids (free amine)
• baking at a lower temperature for longer time: as these reactions happen at higher temps
• limit oxygen exposure by covering with tin foil; reduces direct heat
• precooking the strawberries on the stove at low temp, to limit time in oven where it is under the direct heat