The best place to store seed is in a sealed container in your fridge. Seed stored in a hot garden shed or garage that can reach temperatures greater than 40° in summer will simply die. Seed stored open to the air where it can take up moisture will lose viability.
Pectinase is useful if you have seed with the pulp still sticking on and no amount of sucking, scrubbing or soaking in plain water will remove it. Put in a teaspoonful mixed in water and leave it overnight and the adhering pulp will slip off the seed with gentle scrubbing the next morning. Ref: Samar – India
Hot Water Treatment of Vegetable Seeds ref: Cornell University A hot water soak for vegetable seeds, including tomato, has long been recommended. Soak seeds at 122° F (50° C) for 25 minutes in a water bath with agitation to maintain uniform heat. A dairy or laboratory thermometer is recommended for accurate readings. Following treatment, plunge the hot seeds into cold water, thoroughly dry on newspaper, and then dust with a protective fungicide. Freshly harvested seeds withstand the heat treatment better than do one or two year-old seed and treatment should be made as soon after harvest as possible. Hot water treatment will control seed borne bacteria, but will not eradicate TMV. Similarly, it will have no effect on bacteria borne in the embryo (bacterial canker) or TMV contained within the endosperm.