Cleaning out the refrigerator of out-dated and unwanted food is a task that should be done on a regular basis - and usually isn't done until something starts to smell, or grow fur, or gets shoved 'way back so that someone else (usually the bravest soul in the family) has the terrific job of discarding food that outlived its prime - and time.
My mother-in-law hated to throw food out. Having survived the Great Depression, she hung on to left-overs for weeks - assuring me that she could tell if they'd "gone bad."
I remember a week-long visit to her home in LA when the same plate of boiled beets was offered to us daily at least four times and I, who disliked beets, politely refused the dish each time, as did my husband. What I especially remember (and it has been over 35 years since that visit) is that while baby-sitting our year-old son, she mashed the beets well and fed them to him while we were out for a few hours. Upon our return, the kid promptly gagged and threw up those beets - all over me. I think that was my last visit, so I never again had to deal with her stubborn refusal to throw out leftover foods that no one else was willing to eat.
Hanging onto leftovers is fairly common behavior, judging by the calls I get from the public - so you have a dab of this, a slice of that, a spoonful of sauce or a rind of cheese and if no one is into reconstruction, these foods generally don't improve with age. It's fairly easy to toss those out. What about jars of condiments or cartons of coffee creamer? How long should you hang on to processed, canned or bottled foods? The labels say "Keep refrigerated" - but for how long?
Shelf life of various shelf-stable and refrigerated foods varies, mostly based on acidity and fat content. Very acidic foods are resistant to bacterial growth, so most pickled food has a bit longer lifespan than un-pickled foods. Fats tend to go rancid over time and develop "off" flavors that are quite noticeable. Some items last longer because of their processing or their containers. Let's touch on some commonly stored foods and approximate time-frames for their use or disposal.
Olives, both green and black are fine unopened, for about 1 year. Once they're opened, they have between 1-2 months of a quality life in the fridge.
Sour Cream: Unopened: 2 weeks in the fridge. Opened: 2 weeks in the fridge.
Mayonnaise: Unopened: 2-3 months. Opened: 2 months in the fridge. Be sure to refrigerate after opening, and never leave mayo out of the fridge for more than two hours.
Butter: In the Fridge: 3 months. Salted butter has a longer shelf life than unsalted. Have more butter than you can use? Store extra sticks in the freezer for up to a year.
Pickles: Unopened: 1 year. Opened: 1-2 months in the fridge.
Salad Dressing: Unopened: 10-12 months. Opened: 3 months in the fridge.
Tomato Paste: Unopened: 1 year. Opened: 5 days in the fridge.
Broth: Unopened: 1 year. Opened: 2 days in the fridge.
Half and Half: Unopened: 4 weeks in the fridge. Opened: 1 week in the fridge.
Baby Food: Unopened: 1 year. Opened: 2-3 days in the fridge.
Vegetable Oil: Unopened: 6 months. Opened:1-3 months. For best results, store opened vegetable oil in the fridge.
Juice: Unopened: 1 year. Opened: 1 week in the fridge.
If you cannot remember how long something has been taking up space in your refrigerator, it's time to grab a trash bag and start removing it. Review the contents on a weekly basis and remember that nothing, especially food, is forever.