Mushrooms, asparagus, or rutabagas are some good examples of Specialty Canning Vegetables . One of the golden rules of successful canning is that a good, clean, healthy vegetable cans better, tastes better, preserves better and sells better. Therefore, vegetables undergo rigorous inspection, cleaning, testing and more cleaning and checking to assure that the prepared vegetable is a quality one. Unique to leafy vegetables is that leafy vegetables are tested to see that they are free of any insect infestation, toloyim. The insects that are commonly found in leafy vegetables are known as aphids.
Aphids are small, stubborn predators that attach themselves to the vegetables.
The trap flask test is performed on a sample of leafy vegetables taken from each batch that has been reel washed, paddle washed, pressure washed, and blanched. Two leafy vegetables that commonly present an aphid problem are spinach and kale. Canning companies constantly combat this predator. Through a triple effort of control in the field, development of aphid resistant varieties of spinach, and aggressive cleaning efforts, the normal aphid score is zero on a trap flask test. The pre-canning preparation for other vegetables does not include lab testing but each canner employs their own unique method of ridding the raw vegetables of extraneous matter.