Sugar-Free Blackberry Jam – Tangy, Thick, and No Pectin Required

This recipe has old-school roots and keto-friendly updates. It’s based on a Spanish family recipe that skips the pectin, skips the sugar, and still turns out like the stuff you used to slather on toast as a kid—just without the crash.

With only three ingredients and no weird thickeners, this sugar-free blackberry jam is bold, bright, and ridiculously easy. Spoon it over pancakes, stir it into yogurt, or layer it between low-carb shortbread cookies.

💡 The Secret Behind This Low-Carb Win

Most no-sugar jams either:

• Turn out weirdly gelatinous from added chia or xanthan
• Or they just never set

This one nails it because:

• Xylitol adds sweetness without raising blood sugar
• Simmering the fruit long enough builds natural thickness
• Lemon juice boosts pectin naturally from the berries and balances the flavor
• Letting it rest before cooking helps draw out the juice for better consistency

No artificial stuff. No pectin packets. Just fruit, sweetener, and citrus doing their thing.

🧾 Smart Swaps and Why They Matter

What’s in it:

• ½ kg (about 1.1 lbs) blackberries – Fresh or frozen both work
• ¾ cup xylitol – Sweet without spiking blood sugar (see notes below for subs)
• Juice of ½ lemon – Helps set the jam + adds brightness

🔁 Low-Carb Substitutions That Hold Up

Swap	Result
Erythritol or allulose instead of xylitol	Works, but allulose thickens better over time
Frozen blackberries	Perfectly fine, just thaw slightly
Add ¼ tsp vanilla or cinnamon	Nice flavor twist for toast or pancakes
Want chunkier jam?	Don’t mash the berries all the way

⚠️ What I Got Wrong

What Went Wrong	Why It Happens	How to Fix It
Too runny	Didn’t simmer long enough	Simmer gently until slightly thick—will set more as it cools
Gritty texture	Used granular sweetener not dissolved	Let sit for 1 hour pre-cook so it blends well
Overcooked jam	Heated too high	Low/medium heat is key—don’t rush it

👩‍🍳 How to Make It (Step-by-Step)

1. Prep: Wash fresh berries or thaw frozen ones.
2. In a pot, combine blackberries, xylitol, and lemon juice. Let rest 1 hour (crucial step!)
3. Turn heat to low/medium, cover, and bring to a simmer.
4. Once simmering, mash the berries and stir regularly.
5. Cook a total of 30 minutes (including time to start boiling).
6. Take off heat when it’s a bit looser than you want—it thickens as it cools.
7. Let cool, then jar it up!

🧠 Tricks That Made This Work Better

• Letting it rest before cooking = juice released, better texture
• Mash gently—you control the chunkiness
• Add sweetener gradually if unsure—taste test once cooled
• Store in small jars to avoid overexposure to air

🧊 How I Store and Track It

• Fridge: Keeps 7–10 days in sealed jar
• Freezer: Freeze in small portions for up to 3 months (ice cube trays work great!)
• Serving Size: ~1 tablespoon = about 10–12g
• Net Carbs (per tablespoon): ~2–3g depending on berries and sweetener

❓ Keto Cooking What-Ifs (Answered)

Can I use erythritol instead of xylitol?
Yes, but erythritol may crystallize. Try allulose for a smoother result.

Does this work without lemon juice?
Technically yes, but it won’t set as well. Lemon boosts natural pectin and balances flavor.

Do I need to add chia seeds to thicken?
Nope. Simmering + lemon juice does the trick naturally.

📊 FULL NUTRITION (PER 1 TBSP, APPROX.)

Nutrient	Amount
Calories	~10–12
Fat	0g
Protein	0g
Total Carbs	~3g
– Fiber**	~1g
– Net Carbs	2g
Sugar	~1g (natural)

Check out More Recipes:

• Sugar-Free Raspberry Jam – 5 Minutes, No Cook, No Carb Crash
• Sugar-Free Fig Jam – Naturally Sweet, Thick, and Keto-Conscious
• Sugar-Free Strawberry Jam – Low-Carb, Fruity, and Actually Spreadable