There is a recipe for strawberry jam in the Ball Complete Guide to Home Preserving that doesn't use pectin or sugar - it's just strawberries, apples (for their natural thickening ability) and grape juice concentrate (as the sweetener instead of sugar). It's on page 29. If you're new to canning, I really recommend getting that book as well as the Ball Blue Book.
You can also check out the recipe for Light Strawberry Jam on the Ball website - it uses no/low sugar pectin and grape juice instead of sugar. Browse through their website too - there's a great 'getting started' section that will give you a primer on what canning is all about.
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