Hello Rosalyn
In the formula you have applied, you can create a product with a suitable price and long shelf life with the materials you have. First of all, you should use the skimmed milk powder and milk skim. Or you can use whey powder if you want to replace them with a more suitable and nutritious value. The oil in the milk tozoa and thick milk you use prevents the water activity from decreasing by forming a bond with the starch. Also, when mixing these products, the temperature should not exceed 50 centigrade degrees. If you are already using sodium benzoate and potassium sorbate, it is wrong to sterilize this product for 60 minutes at 100 centigrade. This will cause deformation of your product.
Since the temperature of the product you have filled in hot will be pre-sterilized, it is enough to pasteurize it at 90 degrees until the core temperature is 75. For color stabilization, yam should be subjected to pre-boiled or heated. Please send me a picture of a finished trial to info@alicardak.com and I can help you more.