Another Step for Reducing Waste in Restaurants: Cross-Utilization and Repurposing of Food

Cross-utilization and repurposing are two words that get used by chefs and cooks, but not so much anyone else, so let me first define them for you.

Cross-utilization means using an ingredient, sauce, or condiment that is usually used for one or two specific dishes for another dish or two where, perhaps, they are not expected, or are not usually used. The way my grandmothers, both of whom lived through the Great Depression, referred to it was “making do.”

“Making do,” basically means using what you have on hand, rather than running out and buying something new. Whether this refers to what is in your closet, or what is in your pantry, it is the frugal person’s way of creatively making something new out of something old. And, as I have mentioned before, chefs, as a group, are nothing if not frugal.

For a chef, cross-utilization generally refers to using basic pantry items to make up new menu items or daily specials, which not only avoids having to buy new and different ingredients and uses up what is in the pantry, but it also stimulates creativity. Being limited by a set number of materials and ingredients forces anyone, but certainly a chef, to think outside the box, to work around a problem, to, essentially, turn a limitation into a positive attribute.

I don’t know how many times I have come up with appetizer and dinner specials that use only pantry items, and pretty much every time I have done so, the response from diners has been overwhelmingly positive. It is really cool to be able to make something that blows people away, seemingly out of nothing, and it makes For more on the philosophy of cross-utilization, see my recent post all about it here.

Cross-utilization, or making do is something that every home cook probably has done in the past, especially in times of financial stress, but it is good to try and do it as often as possible anyway. It is a good habit to get into. Not only does it cut food loss and waste, it helps keep a cook creative when it comes to thinking of ways to cook different ingredients and differing presentations of everyday dishes.

For example, a while back, my parents planned to come visit us for the day, which would be their first big driving expedition after Dad’s surgery. Morganna and I wanted to make Indian food, so when we went shopping, we kept that in mind. We ended up picking out some purple cauliflower which we intended to make into aloo gobi–curried potatoes and cauliflower. However, my Mom caught a nasty cold which turned into bronchitis, so we never got around to that planned feast.

Instead, a week later, when I came home from work late Saturday night, and found extra folks around at dinner time (I forgot that it was Torchwood and Dr. Who night–silly me!), even though I was planning to have keema mattar, which is minced lamb with peas, I saw the cauliflower and decided it would work perfectly well in the dish in addition to the canonical ingredients. And it did. It worked so well, in fact, and looked so pretty (I love how fresh green and purple look together!) and tasted so nice that it was remarked upon by everyone who ate it, and so I will be making my keema mattar gobi again. And the truth is, I would never have thought of it in the first place if I had not had cauliflower sitting around needing to be used and a mind open to culinary possibilities.

Repurposing food is a similar process to cross-utilization, but instead of pertaining to using ingredients in more ways than you had originally intended, it has to do with creative use already cooked food. You know–leftovers.

Yes, leftovers. Even restaurants have them and, if they want to keep their food cost down, chefs have to figure out how to use them.

Sometimes, leftovers are made on purpose in restaurants. If one is going to make a stew or soup that will freeze well, and you have space for it in your freezer, why not make twice as much (which takes not much more time than a single batch) and cool some down and freeze it, properly dated and marked, for a later date? Every chef needs a quick lunch or dinner special now and then; sometimes, in the middle of a shift, a soup runs out and you need another one very quickly. It is nice to be able to heat up something which you know is good, in a matter of minutes, when unforeseen circumstances strike–the special runs out, the cook who was supposed to make the soup is deathly ill with pneumonia and had to be sent home, or the gas line is leaking and you can’t use your stove, but you still have people to feed.

But even if you didn’t mean to have leftovers, sometimes they can be frozen and used later. There are a few guidelines about doing this–the leftover food should only have been cooled and reheated once, and it should be cooled to below forty degrees F. before being put into the freezer. This is for food safety concerns–the more times food is cooled and reheated, the more chances there are for harmful bacteria to proliferate. In addition, food that has been cooled and reheated more than once or twice suffers greatly in quality–food textures go awry, the colors can fade or oxidize and turn brown and the flavor balance can be upset beyond repair.

In some cases, you can make one dish, and turn it into something completely different. A classic example is where cooks diners and similar restaurants will save leftover baked potatoes and make baked potato soup the next day. Leftover keema sookh–a dry curry made from minced lamb, beef or chicken, can be mixed with rice, vegetables and spices and then be used to stuff roasted vegetables the next day. Taco meat can become chili, leftover rice can become rice stuffing or fried rice and leftover bechamel sauce can be turned into mornay sauce with the addition of grated cheese, which can then be used in any number of other dishes. Leftover vegetables can be saved and made into soups, either as mixed vegetable soups, or as pureed cream soups. Leftover bread can be fried into croûtons which can then garnish salads and soups, or it can be made into one of my favorite desserts of all time–bread pudding. Leftover tortillas can become the garnish for sopa de lima–a tangy chicken and lime soup with a garnish of fried tortilla strips–and leftover roast meat can become the basis of a soup, a salad, a casserole, or a sandwich or dumpling filling.

For an example of how I took an unpopular dinner special made one night and turned it into a completely new dish that sold out the next night, read this post which also is a rumination upon the art of cooking and even more importantly, naming and marketing dinner specials.

There are so many ways to use leftovers in both a restaurant and home kitchen that there isn’t really a great excuse for a lot of the food waste that goes on in the United States. But even though there are ways to re-use or repurpose food, you have to follow strict sanitation procedures and food safety guidelines in order to ensure that the leftovers are handled properly so that no diners get sick. Only foods which have been handled properly should be repurposed, which means that if a food has stayed between the temperatures of 40 and 140 degrees F. for more than four hours, they should not be used. (That range of temperatures, known in restaurants as “the temperature danger zone” or “TDZ” for short, is the perfect temperatures at which most harmful bacteria thrive and grow.) When in doubt about the safety or the quality of a food, it is best, if regrettable, to throw it out. (Another industry catchphrase–“When in doubt, throw it out!” is a good principle for home cooks to live by as well.)

Now that I have discussed the biggest techniques that help restaurant cooks and chefs decrease food waste and thus keep food costs low, all of which can be modified for home use, my next post will be about -why- there is so much food waste in American restaurants, and what can be done about it.


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  1. I think I was the first person who ever fed you bread pudding.

    Comment by Azalais — April 10, 2008 #

  2. You were not the first person to feed me bread pudding, Kiri–you were the first person to feed me bread pudding that I liked.

    The only other bread pudding I had ever eaten was made by a person who could barely cook, and it was soggy and icky. I think it was undercooked. Blah.

    Yours, on the other hand, convinced me that there must be something to this bread pudding idea, and I became a convert. 😉

    Comment by Barbara — April 10, 2008 #

  3. I haven’t thoroughly read all your posts on reducing restaurant food waste, but I read this one, and I hope I can make time to go back and read the others. Making do has always been big in my kitchen. I hate having to throw food away.

    My stepdad makes software for managing the food ledger that I’ve always thought was cool, but never had an opportunity to recommend to anyone in a position to use it. I have no idea how he has marketed or distributed this, so you may have heard of it already, but if not, check it out (or not :D): CostGenie.

    Comment by Erin — April 10, 2008 #

  4. Do you have (and want to give) the recipe for sopa de lima? Sounds lovely.

    Comment by Christy — April 10, 2008 #

  5. How do restaurants handle the issue of whether there’s enough of the leftover item to make enough of the new dish?

    Comment by Harry — April 11, 2008 #

  6. Now I have a fancy word for “This recipe I want to make uses Weird Ingredient X, so I need to find another recipe for this week that uses WIX too.” 🙂

    Comment by Alexis — April 11, 2008 #

  7. Leftover or day old french bread makes wonderful croutons for vegetarian stuffing since I can’t buy the regular ones due to chicken broth. The first time I made it, I think I was more interested in the stuffing than the homemade tofu turkey!

    Comment by vegoftheweek — April 11, 2008 #

  8. Harry: Usually they just use what they’ve got until it’s gone. Usually such a dish is put on as a special, and when it’s gone; it’s gone. It’s usually not meant to last a whole service or even a whole day. I do this a lot at the bakery with the fresh fruit I have to use up. For example, I’ve got 4 pears that are very ripe and have to be used today or they go in the trash, so I’ll make enough frangipan-pear tarts to use up the product, and I’ll sell it till it’s gone. Hope that makes sense.

    I would like to say that the bakery I work for donates all leftover bakery product at the end of the night to soup kitchens and charities. We do what we can, but it is frustrating when the bread/pastries are not picked up as promised, because then we do have to pitch it–as it can’t be sold the next day.

    Comment by Roxanne — April 11, 2008 #

  9. This post makes me very happy in a way I can’t even quite put my finger on. Just the notion of making do, I guess – a concept that I feel has gone out of the window in all of our excess, but perhaps seems primed for a comeback.

    Comment by Ali B. — April 11, 2008 #

  10. Roxanne –

    What you wrote makes fine sense, although I imagine there’s a point at which having too many “we’re out” in a night or as a general reputation is a negative.

    About your bakery’s bread problem: I’ve had some experience from the other side. Food kitchens are often overwhelmed with breadstuffs and beggars can be choosers. They’ll only eat so much bread pudding, french toast, and pan dowdies. Then there are some oddities, like the local soup kitchen that has its own bakery. So the explanation may be poor planning, shortage of resources, or actual lack of need.

    Comment by Harry — April 14, 2008 #

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