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A short glossary of the packaging-science terms behind every recommendation — so the numbers on your results page actually mean something.
OTR — Oxygen Transmission Rate
How much oxygen passes through a packaging film per day, per unit area (cc/m²/day). Lower OTR means a stronger oxygen barrier — important for oxidation-sensitive foods like nuts, chips, and coffee.
WVTR — Water Vapor Transmission Rate
How much moisture vapor passes through a film per day, per unit area (g/m²/day). Dry goods need a low WVTR to stay dry; some fresh produce actually needs a moderate WVTR to avoid condensation.
MAP — Modified Atmosphere Packaging
Packaging that alters the internal gas composition (O2, CO2) around a fresh product to slow respiration and extend shelf life — done via breathable or micro-perforated films matched to the commodity's respiration rate.
Respiration rate
Fresh fruits and vegetables keep "breathing" after harvest, consuming O2 and producing CO2. Packaging must let enough gas exchange happen — too little causes anaerobic spoilage, too much wastes the benefit of MAP.
Mono-material construction
A package built from a single material (rather than a multilayer laminate) is much easier to recycle — a smaller number of distinct materials is one of the sustainability signals NutriWrap scores.
Water activity (aw)
A measure (0–1) of how much "free" water is available for microbial growth in a food — distinct from moisture content, and a strong predictor of shelf-life risk.