The target temperature for a pantry is 10–21°C / 50–70°F; above this range, fats go rancid, spices lose their aroma, and insect activity speeds up. Humidity should be low and steady: signs include shelves that feel dry to the touch, no condensation inside jar lids, and packages that have not softened.
The shelf life of dry foods depends on the environment as much as on the packaging. Flour, legumes, rice, pasta, nuts, spices, oil, and sealed canned goods all last the longest in a cool, dry, dark place with a steady temperature. The target temperature range is 10–21°C / 50–70°F. As the temperature rises above this range, fats go rancid faster, volatile oils in spices are lost, chocolate softens, and insect eggs develop more quickly. Going below this range is harmless for most products as long as they do not freeze; a frozen can bulges and may leak at the seam.
Humidity is even more important than temperature, and you do not need a tool to measure it. When humidity in the pantry rises, the signs appear: flour and powdered sugar clump, salt stops flowing, crackers and nuts soften, condensation gathers on the inside of jar lids, cardboard packages warp, and labels lift off. The surface of a shelf should feel cool and dry to the touch; a damp or sticky shelf means the cabinet is not suitable for dry storage. Rust spots on metal lids are another warning and are usually the earliest visible sign.
By these measures, some places do not work as pantries. Cabinets next to the stove, oven, dishwasher, or the hot grille on the back of the refrigerator warm up and cool down during the day; this fluctuation alone shortens shelf life. The cabinet under the sink is both damp and vulnerable to plumbing leaks. A shelf above a radiator and a sunny windowsill are ruled out for the same reason. Garages and balconies are not used as dry-food pantries because their temperatures fluctuate freely with the seasons.
Once you find the right place, a few simple steps keep the environment steady. Keep the cabinet door closed, turn on the light only when using it, and do not put clear jars on a bright shelf; light degrades both oil and spices. Provide ventilation, but do not let airflow come directly from a damp area. If you see mold spots on a wall or ceiling, resolve that problem before setting up the pantry, because mold spores settle on dry-food packaging and wait for an opportunity there.
Once the environment is right, packaging completes the job. Transfer every opened package to an airtight glass or plastic container; an open package of flour or legumes attracts moisture and insects much faster than the pantry’s dry air does. Keep products off the floor and slightly away from the wall, write the opening date on containers, and empty and wipe the shelves a few times a year. Even the best pantry will not provide the expected shelf life if its packages are left open; the environment and packaging do not replace each other, but work together.