how long does fresh juice actually last?

the juice on grocery shelves that says "fresh" but sits unrefrigerated for weeks has almost always been pasteurized or HPP-treated (high pressure processing) — a cold pasteurization method that kills bacteria and drastically slows oxidation. that's not something you can replicate in a home kitchen, and honestly, you don't want to. pasteurization also flattens flavor and kills some of the enzymes people are juicing for in the first place.

when you juice at home, there's no processing step between the press and your glass. that's the whole point — but it means the clock starts the second the juice hits the jar.

cold-press and masticating juicers produce juice with less oxidation than a blender-and-strainer method, because they crush rather than shred — less surface area gets exposed to air. juice from a cold-press juicer, stored properly, holds up for about 48-72 hours.

juice from a centrifugal juicer (the fast, spinning-blade kind) or a blender-and-strainer setup oxidizes faster because more air gets whipped into it during processing. give that 24-48 hours before quality really drops off.

you'll know it's turned before any label would tell you: the color dulls first (bright beet-red goes muddy brown-red), then the smell turns slightly fermented, then it separates in a way that doesn't re-shake back together.

store it in glass, not plastic — plastic can leach flavor over time and doesn't block light as well. fill the container as close to the top as you can; less air trapped inside means less oxidation surface.

keep it cold and keep it dark. a fridge door gets opened constantly and lets in light and temperature swings — store juice toward the back of a shelf instead.

if you're making a big batch on a sunday to get through the week, juice things like beets and carrots first since they hold up longest, and treat anything with cucumber or leafy greens as a drink-within-24-hours situation.