fresh household scrap in the compost bin
Photo by Ghavasi courtesy Adobe Stock fresh household scrap in the compost bin

Culinary indulgences are a traditional part of holiday celebrations for many, yet they also highlight our inefficient practices when it comes to food waste. According to the United Nations Environment Program, one-third of the world’s food is wasted or lost annually. In the U.S. alone, food waste comprises more than one-fifth of the waste stream and occupies the highest volume in landfills, at 133 billion pounds of edible material. In a recent recent City A.M. article, Elsa Bernadotte, chief operating officer of the food-saving app Karma, claims, “Food waste will be next year's moral crisis, just as single-use plastic was this year.”

Fortunately, several pioneering designers and manufacturers have developed a variety of alternative building materials made from discarded food.

According to the Food Wastage Footprint report by the Food and Agriculture Organization (FAO) of the United Nations, “Wastage of cereals in Asia emerges as a significant problem for the environment, with major impacts on carbon, blue water, and arable land.” Rice is of particular concern, given the volume of waste as well as the significant quantities of methane released by rice paddies.

However, once about 80 percent of rice and bran are harvested, the remaining portion of rice husk can be used as fuel as the byproduct rice husk ash (RHA). This material has reactive pozzolanic properties, making it an excellent supplemental cementitious material. Watershed Materials, a manufacturer based in Napa, Calif. (the second highest rice-producing state in the U.S.), has developed a concrete masonry unit that incorporates rice husk ash in place of 30 percent of Portland cement. The company blends local, dark basaltic aggregate with the similarly colored ingredient to make its graphite-hued, smooth-finish block. Although Watershed Materials’ recipe is tailored to its particular context, RHA-based cement can be readily manufactured throughout Asia where the quantity of rice waste is most significant.

Discarded animal protein is the most concerning kind of food waste, given the massive ecological footprint of livestock farming. One-third of the world’s crops and a quarter of its freshwater go to livestock production, which in turn contributes about 15 percent of all greenhouse gases. According to a 2014 Guardian article, “When you consider the real costs, it becomes startlingly clear that some of the worst things you can waste are meat and dairy.”

The high protein content of meat byproducts, such as blood meal, makes the waste a useful feedstock for new biopolymers. Researchers at the University of Waikato, in New Zealand, have devised a process to convert bovine blood meal, a nitrogen-rich powder made from animal blood, into a biodegradable thermoplastic. Based on a previous recipe developed by local Aduro Biopolymers for Novatein thermoplastics, the engineers added additional copolymers to improve the strength and durability of the material. The potential benefits of the blood meal bioplastic are multiple: usable protein may be extracted from discarded meat while offsetting the need for non-biodegradable, petroleum-derived polymers.

The perishability of fruit makes it particularly susceptible to landing in the rubbish heap. The FAO publication reports a widespread concern about discarded fruit throughout Latin America, Asia, and Europe. A 2018 study by Karlstad University, in Sweden, determined that only seven products account for nearly half of the total waste of fruits and vegetables in supermarkets. The worst offender of these was the banana. According to a summary by ScienceNordic, “Bananas were wasted more than any other product in overall weight and they also have the highest climate impact.”

Fighting this trend, Netherlands-based company Leoxx harvests banana fibers to create carpets and other soft textiles. A robust and lightweight material, the fibers are commonly used for industrial products like woven mats and ropes. Similarly, Philippines-based Ananas Anam offers Piñatex, a textile made from pineapple leaf fibers. Developed by scientist Carmen Hijosa, the novel non-woven fabric transforms a common agricultural waste product into a commercial-ready textile for a variety of applications.

While many bananas rot on store shelves or in the home pantry, much fruit and vegetable waste occurs before reaching consumers. According to a study by researchers at the University of Udine, in Italy, fresh-cut salads are particularly problematic, as 40 percent may be wasted during processing alone.

Courtesy Chip[s] Board

The two most cultivated crops globally after wheat and rice are potatoes and corn. Their large production quantities alone make them good candidates for waste analysis as several manufacturers have noted. Potatoes have been the focus of Netherlands-based Crustell, which developed a cork-like product from dried potato skins. More recently, two Kingston, U.K.–based designers created Chip(s) Board, a product made from discarded restaurant potatoes resembling chipboard. The German manufacturer Wood K Plus has developed Maize Cob Board, a composite building panel that uses disposed corn cobs for the interstitial material. At only half the weight of traditional fiberboard products, the sandwich product also exhibits good thermal insulation properties.

Closing the Loop
A circular economy model defines food waste as both a problem and a resource, depending on how it is used, thus inviting further consideration about resource streams. In a 2017 report entitled "The Urban Bio-Loop: Growing, Making and Regenerating," global engineering firm Arup proposes an alternative model to conventional waste management in an approach based on organic waste exploitation. The report identifies six primary building applications for organic waste—interior finishes, furniture, acoustic treatments, insulation, carpets, and envelope systems—arguing that such uses have inherent economic and environmental value. True cradle-to-cradle thinking should go even further, taking into consideration discarded building products that are intrinsically beneficial for growing food—thus completing the cycle.

In other words, if food waste can become new products, then product waste should fuel new food. In this way, the concept of nutrition will assume a broader, multifaceted meaning in the fortification of our bodies, the structures we inhabit, and the soil that replenishes both.