March 1, 2004 | General

Quantifying Food Residuals In Campus Cafeteria

Ben Van Handel
BioCycle March 2004, Vol. 45, No. 3, p. 43

Like many other residential campuses, Northern Michigan University (NMU) in Marquette, provides food services for its students. The Marketplace is the largest dining facility and is set up in buffet fashion. One flat rate ($5.00 for breakfast, $6.75 for lunch and dinner) allows a student, faculty member, or visitor to eat as much as they would like. The Marketplace menu runs on a three-week rotating cycle, with the main courses differing on each day. After three weeks, the order of dishes repeats. For most students, varying meal plans, covered under the room and board portion of their tuition, provide a number of entries into The Marketplace per week.
One unintended consequence of this “all you can eat” approach to food delivery is the generation of food waste. Any visitor to The Marketplace who returns their tray to the conveyor belt leading to the dish room will notice uneaten portions of food on slowly retreating trays. At a time of rising costs for students, food waste represents a possible source of savings. A reduction in food waste could potentially result in less food being purchased, and these savings might then be passed on to students in the form of a less expensive meal plan.
A research project was undertaken at NMU to calculate the amount of food that students are throwing out and to identify possible opportunities for reduction. Previous research studies provided some data. For example, a 1983 study found plate waste to be an estimated 8.8 oz./person/day at a Washington State University dining hall serving approximately 2,500 meals a day. Extrapolating this estimate over a whole semester, the cost of food waste amounted to $26,400. However, this study was performed in a dining facility where single portions of most items were served. Students were allowed as many single portions as they wished, served one at a time. No such control on portion size exists at The Marketplace, where about the same number of meals are served per day.
A 1991 study collected plate waste from 10 percent of all trays returned to the dish room during a meal period at a dining hall at the University of Maryland. Food items were divided into categories and weighed. An estimated 17 percent of all food served was wasted. Portion control procedures were in place for initial servings and students were permitted unlimited seconds. To control plate waste, the authors recommended strict portion control and a student education campaign on the costs and implications of waste.
To determine an accurate figure for total food waste at The Marketplace, a stratified sampling procedure was utilized. Each day was divided into four time periods (breakfast, lunch, afternoon, and dinner), with the number of waste collections corresponding to the percentage of total daily student attendance present at that time. (Differences in eating patterns on the weekends were taken into account during sampling.)
Food residuals that entered the dish room were removed from trays after the flatware and dishes had been cleared, placed in a bin, and weighed at the end of one hour. Inedible food items, like bones and banana peels, were not weighed, nor were beverages or milk leftover from cereal. Each collection was weighed on the same scale. Collections were then averaged for each time period to produce a figure, in pounds, for waste per hour. This figure was then multiplied by the number of hours in the time period to estimate the amount of waste generated. Finally, the totals for each time period were then summed to determine a figure for waste per day. To illustrate the extent of food waste in a specific entrée, all pizza produced in a single day was weighed before cooking, and then the pizza waste produced by students was intercepted and weighed.
To estimate the dollar value of this waste, the total cost of food ordered by The Marketplace from their main vendor during a three-week period was divided by the food weight, to derive a cost per pound of food.
An estimated 748 pounds of food waste were generated each weekday and 670 pounds on each weekend day, which amounts to 2.5 tons a week or a loss of $9,296. Over the course of a semester, from the first day of classes to the last (with one week removed for vacations like spring break and Thanksgiving), an estimated 38.1 tons of edible food are thrown away, costing nearly $140,000. This dollar amount does not include costs of service waste or septic pumping charges; it only represents student-generated waste. Currently, food waste is washed into a trough, ground in a garbage disposal and stored in a 6,000 gallon holding tank. NMU pays a septic pumper to empty the tank several times a year. This material is land applied by the contractor.
During an average week, 17,472 meals are eaten at The Marketplace according to dining services records, which translates into 4.7 oz of food wasted per meal. If each student at The Marketplace eats only two meals per day, 9.4 oz of food is wasted. These findings suggest that the “all you can eat” policy is responsible for generating more waste than a strict portion control system, since NMU students average 9.4 oz of waste a day versus the Washington State University figure of 8.8 oz. Student waste of pizza provides further support for these findings, with an estimated 25.1 percent of all pizza taken by students for consumption returning to the dish room as waste.
At the University of Wisconsin-River Falls (UWRF), a school comparable in size to NMU, composting of food residuals was undertaken with the help of a grant from the Wisconsin Department of Natural Resources. Organic materials, including cheese, vegetables and meat, plus used paper products, were collected in large containers from several dining areas on campus. The materials were then transported to the university farm, where they were spread out and covered with other organics, such as manure and soiled animal bedding, forming windrows, and then allowed to compost. Temperatures necessary for degradation were maintained throughout the winter, important because the climate in Wisconsin is comparable to that of the Upper Peninsula where NMU is located. Composting was found to be an economically feasible alternative to typical solid waste disposal methods, with little change in waste collection procedures.
The compost produced was of good quality and was available for use on the campus grounds, producing further savings.
At the University of Minnesota at Duluth (UMD), an all-encompassing system of responsible waste management has been implemented. Several years ago, UMD purchased a machine that removes water from food waste; the resulting pulp is composted by a local waste management company. The company cut the rate that it charges UMD for disposal in half, due to plans to sell the compost.
In 2002-2003, NMU paid $57,486 in water and sewer facilities for The Marketplace alone. A very high proportion of this cost is attributed to water used for dish cleaning and rinsing all the food off of trays and dishes so it can be flushed down the trough to the septic tank. For example, a jet at one end of the trough continually sprays a stream of water whenever the disposal is running. In addition, there are two heads that spray 1.5 gallons of water/minute to help workers rinse the dishes. With implementation of a food recycling program, this figure could be reduced significantly.
Other options exist for wasted food. A significant portion of waste from The Marketplace consists of fully prepared food that has never reached the buffet. The university refuses to consider a donation program to the needy of the Marquette community, with most of their concerns revolving around lawsuits and liability. However, the Good Samaritan Food Donation Act of October 1996 “limits the liability of donors to gross negligence or intentional misconduct” (See “Increasing Edible Food Recovery,” February 2004). Donation of extra foodstuffs would not only save money, but also provide a valuable service to Marquette residents. Alternatively, NMU could process the organic materials into livestock feed. If dehydrated and pelletized, the university could potentially receive as much as $146/ton for food residuals.
Ben Van Handel is a student in the Department of Biology at Northern Michigan University in Marquette.

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