AQUALAB Research Report | August 2026

In the literature

Setting the target, then finding the route

Sweet potatoes spoil fast. Turned into flour they keep – but only if enough water comes out, and only if the drying doesn’t wreck the beta-carotene that makes orange sweet potato worth eating. A team in Mato Grosso made the flour four different ways, cutting the roots into chips or cubes and drying each with heat or by freeze-drying. Every route had the same requirement: get water activity below 0.3, the point where microbes have nothing left to work with. An AQUALAB 4TE confirmed where each batch landed. Freeze-drying overshot to 0.07. Oven drying stopped at 0.26 – still safe, and far cheaper to run.

The more useful finding came out of the correlations. Water activity moved together with beta-carotene retention, echoing earlier studies that point to a middle range where the pigment holds up best: a little leftover water appears to get in oxygen’s way, while too much lets oxidation take over. The window isn’t settled science, but the implication for anyone drying produce is practical: bone dry may not be the goal. There may be a right amount of water, not just a ceiling.

The other end of the scale

The month’s other citation is the opposite case. A Spanish team is pulling flavor compounds and health-active peptides out of pig liver, an organ most processors treat as waste. Before starting, they measured what they had: fat, protein, pH, and water activity at 0.994 — about as high as the scale goes. Fresh liver is, for practical purposes, water. Every step that follows is a move away from that number.

In the conversation

In July, USDA’s Agricultural Research Service went looking for a water activity meter and titled the request “Water Activity Meter (Brand Name Aqualab or Equal).” Federal rules push agencies to describe what they need rather than name who they want to buy from, so a brand name plus “or equal” says the category has a reference point — while inviting anyone to match it. The specification it wrote out was AQUALAB’s: chilled-mirror dew point sensing, readings to four decimal places, accuracy within 0.003. Twenty-two offers came back. The award went to Addium.

The meter is headed to a lab in Wyndmoor, Pennsylvania that studies foodborne pathogens in low-moisture foods — the flours, powders, and dried products where salmonella can survive for months without enough water to grow in. Knowing how much water those products actually hold is where that work starts. It is the center’s second AQUALAB order this year.

Zachary Cartwright, AQUALAB’s lead food scientist, was quoted throughout Southern Living’s case against wrapping leftovers in foil. His argument is a moisture argument: foil crinkles instead of sealing, so air keeps reaching the food — and food losing water to the air is losing quality along with it.

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AQUALAB Research Report is a monthly roundup of notable citations, mentions, and technical references involving AQUALAB instruments and water activity science. 

See something we missed? Send it our way for inclusion in a future installment.

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