Ever wondered why some foods tend to rot as soon as you get them home while others have miraculous shelf-lives? It could have something to do with how old some foods are before you even buy them. Below, we break down some commonly purchased goods that are as fresh as possible—and a few that might be a little older than you think.

1. ORANGE JUICE

Is your orange juice actually made from fresh oranges, like many OJ companies market? Likely, no, says researcher and author Alissa Hamilton. According to Hamilton’s investigation, “not from concentrate” orange juices are stored in million-gallon tanks for up to a year before being bottled and sent to grocery stores. Orange juice is first pasteurized, has its oxygen removed and then is stored in tanks. When it’s ready for packaging, orange juice manufacturers add in "flavor packs” to boost the orange taste.

2. APPLES

If you’ve ever picked an apple from the tree and wondered why it tasted different than store-bought fruit, it could be age. Apples can be up to a year old by the time you buy them, though they’re still safe to eat. Year-round apple demand means that a short harvest season—usually from late summer to early fall—somehow has to provide a supply for the following year. To make apples last, harvesters store the fruit in low-oxygen, high-carbon dioxide coolers, sometimes applying fungicides to prevent rot, or 1-methylcyclopropene, a gas that stops apples from emitting the ethylene gas that causes them to ripen and age. Other apple producers use wax coatings to help the fruit retain moisture and appear fresh, which isn’t too unnatural since apples produce their own protective, waxy layer that is often lost during harvesting and washing.

3. EGGS

There’s a lot of debate about what kind of eggs you should buy—cage-free, free-range, organic, or whatever’s cheapest. But most eggs have age in common, and they can be up to 45 days old before they’re no longer sellable. While most egg cartons come with an expiration or “best before” date, egg processors technically don’t have to stamp their cartons so long as their eggs are graded by the United States Department of Agriculture (USDA). If they do label eggs, there are basic rules: expiration dates can’t be any more than 30 days from when the eggs were packaged, and grocery stores can’t sell them after that date. If “best before” stamps are used, the date on the package can’t be any more than 45 days from when the eggs were carton-packed. U.S. egg regulations are different than other countries', mainly in that American eggs are washed and chemically sanitized before being refrigerated and shipped to stores. Throughout Europe, eggs aren’t washed, and producers instead use an egg’s natural protective coating to keep it safe before reaching shoppers.

4. BEEF

Grocery store beef is often a bit older when it gets to you, but that doesn’t mean it’s no good. Many cuts of beef are aged before they’re sent off to packaging and shoppers, and that means it can be nearly six weeks old by the time you add it to your grocery cart. Aging uses microbes and enzymes to break down some of the tissue, with the goal of naturally tenderizing meat. How it’s done depends on the beef producer; some sides of meat are simply hung in large coolers, while other meats are wrapped in plastic bags before being hung. Each way has its own effect on how meat ages. So, how do you identify good beef in the meat department? The trick is to look for red, not brown, meat. Vacuum-sealed meat often looks purple, but beef that’s been exposed to oxygen turns bright red. It’ll turn brown about five days later because of natural chemical changes, and can feel tacky or smell “off” any time after that.

5. POTATOES

The age of root vegetables like potatoes may not come as a surprise because of how long they last in dark pantries at home. After being harvested, potatoes are stored in large, temperature- and humidity-controlled warehouses where airflow systems keep 20-foot-deep potato mounds from rotting. They can stay this way for up to 11 months before heading off to be cleaned and packaged. If you’ve ever wondered where those bumps and nicks in your potatoes come from, it’s the harvesting process. As potatoes are pulled out of fields, harvesting machinery can rough them up a bit. But properly stored potatoes can heal their bruises and cuts within two weeks.

6. LETTUCE

Leafy greens like lettuce can be fresh, or a few weeks old, depending on where you live and what kind of lettuce you buy. Nearly 90 percent of lettuce sold during the winter in the U.S. comes from Yuma, Arizona, where it’s warm enough for the plants to grow. Shipping times vary based by destination, meaning lettuce could be just a few days old, or longer if refrigerated before and during transport. But, bagged lettuces and greens can be up to two weeks old from the time they’re harvested, cleaned and packaged, and shipped to stores.

7. BREAD

There’s no clear answer to how long bread can sit on grocery store shelves before it’s tossed, since every grocery store has its own standards for food loss. But there are ways to tell when your bread was baked. Bread tags are often color-coordinated to note what day of the week a loaf was baked, such as blue for Monday or green for Tuesday. This color tagging makes it easier for bread distributors and store stockers to rotate out fresh loaves without having to stop and look at each package’s date. But, that doesn’t mean you should completely rule out the old-fashioned squeeze test, because not every bakery follows the same color-coordinated tag system. As for how long your loaf will last at home, it depends on how you store it. On the counter, bread should last five to seven days [PDF], but refrigerated bread can last longer. If you come across a good bread sale, there’s no harm in freezing extra loaves, which retain peak flavor for up to three months.

8. MILK

Milk normally leaves a dairy, is pasteurized and bottled, and arrives at grocery stores within 48 hours. While that’s pretty fast for a food that expires quickly, it doesn’t mean that shoppers aren’t still conscious of “best by” dates when picking up a gallon. So if milk is relatively fresh when it arrives, how long can it stay in the grocery cooler? That depends on each state’s rules and can vary between 12 and 21 days after milk has been pasteurized. At home, using the “best by” stamp to determine freshness isn’t a hard and fast rule because refrigerator temperature, level of pasteurization, and other factors (like backwash from drinking out of the carton) affect how long milk lasts. The sure-fire way to know if milk has spoiled is the age-old sniff test.

9. CRANBERRIES

Cranberries have made a name for themselves during fall and winter celebrations. But, it’s not just the holidays that increase cranberry sales. The bog-dwelling berries are actually harvested during their popular season, and make their way to grocers soon after. When ripe, cranberry marshes are flooded and the berries are pulled from their vines by rotating machines called beaters. The berries then float to the top of the marsh and are collected. Cranberries bought in September, October, and November are usually fresh, but they will last in freezers for up to a year.

10. DELI FOODS

If you’re swinging by the grocery deli for a roasted chicken or quick meal, it’s probably nice to know that your food was likely made that day. Most grocery store delis toss leftover, prepared foods that were cooked that day. In many cases, they aren’t packaged for sale the next day or even sold to employees clocking out for the day. The grocery industry can lose millions by throwing out this food ($900 million in 2001, by one survey's estimate), but they'll pass that cost on to the consumer. That's why the sliced-while-you-wait deli meat costs more than the very similar package in the aisle. But, in terms of freshness, the deli counter is great bet.

All images courtesy of iStock