Rest-intake is the amount of food that returns in the plates of the diners. The daily recording and evaluation of the quantity is important to define strategies to reduce waste, increase productivity and sustainability of the food and nutrition unit (FNU). Study carried out at a private school in the city of Rio de Janeiro, 500 lunches are served daily for students/employees, always with two protein options. Data collection took place for 20 days, in August and September/ 2019 and only the amounts of the rest of the protein intake were considered. For comparison and improvement confirmation, data from previous period was used when buffet was unlimited for all food including proteins. In the total of 1,565 kg of food served there was a rest of 58.64 kg, which is equivalent to 451 meals monthly. On average, the FNU had a percentage of waste close to 14% during unlimited buffet, which was improve to a waste level at 3.75%. The new waste outcome of the FNU is within what the literature data considers optimal, with remark that data collected are only for protein. It would be necessary to analyze all the rest-intake to determine with accuracy, but the wasted amount of protein, the most expensive input of preparations, indicates that the waste is higher than the ideal. From unlimited to limited buffet option, huge improvement in protein waste management was shown (ca. 10%), however, with some additional modifications including amount of chicken per portion as well as presents of chicken and beef as most liked proteins, would potentially further improve, and reduce protein waste.

The Food and Nutrition Units (FNUs) are spaces where activities aimed at preparingmeals are carried out, with the aim of producing food within hygienic standards, seeking diner satisfaction, quality, and productivity [1]. In Brazil, 39 million tons of food are discarded daily, which is equivalent to twelve billion reais (ca. 3 million USD) a year [2]. Food waste in a FNU can be evaluated throughthree methods: diners’ leftovers (plate), dirty buffet leftovers (buffet), and clean leftovers (kitchen) [3]. The rest-intake is the amount of food that returns on the diners' trays and plates. Some factors may affect the increase in this rate, such as the size of the plate and the utensils used for distribution; these can cause an excessive amount of food to be served, increasing waste and consequently costs [4].

The daily registration and evaluation of the amountof waste and leftovers is important to define strategies aimed to reducing waste, increasing the productivity and sustainability of a FNU [5]. This control required evaluating the efficiency of the FNU, where the nutritionist has a fundamental role in the planning and cost control [6]. In food and nutrition units, waste causes high financiallosses, especially with proteins. A study carried out at the FNU of a University Restaurant determined a waste of 804.4 kg of food in ten days, with the cost of the rest-intake of lunch totaling an average of R$ 572.59daily (ca. 150 USD) [7].

We learned that school kitchen had open buffet policy. Every student had right to take food as much as possible on one time service. With that approach protein waste on the monthlybase was close to 14% whichis by international classification very poor food and waste management[8]. Considering that the rest- intake, mainly of protein, can cause financial losses for the FNUs of any institutions, this study was carried out to check if controlled service conditions would improve waste management and reduced costs. Main objective of this study is to identify the impact of the loss of animal protein,in a Food Unit and Nutrition at a private schoolin the west zone of the city of Rio de Janeiro with the new limited food access regime. Finally, old and new system will be compared with numerical findings as well as further recommendations for improvement and better management of most expensive part of the meal, in this case animal proteins.

The present study was carried out in a Food and Nutrition Unit (FNU) of a private school in the west zone of the city of Rio de Janeiro.

In this FNU, breakfast, lunch and afternoonsnack are provided for diners. For the purposes of this study, onlythe amounts of the rest of the protein intake from lunch were considered, since it is the meal that concentrates the most significant part of proteins, object of the study. Approximately 500 meals are served from 11:00 am to 2:30 pm. Data collection was carried out on 20 consecutive business days, in August and September 2019 (Figure 1). For comparison with old system of unlimited one time served buffet, 20 consecutive business days data were used from April 2019.

Figure 1: Study protocol.

*FDS – free days

The menu is different every day, always having two protein options for diners to choose from. Two servings of protein are offered per person, totalingan average of 130 g and must be served the first time the diner passes through the buffet. The other preparations can be served more times, without restriction, although all foods are served by maids.

Dirty leftovers (protein left over from the buffet) and clean leftovers (protein left over from the kitchen) were not included in this study.The rest ingestedwas measured by the evaluator at the FNU right after the diners left their plates at the pass-through using a Ramuza DCR CL30 model scale with a capacity of 30 kg.

The number of menus, as well as type of proteins and food  amount  was  the  same  in  both  service approaches, unlimited and limited, with relative standard deviation for each of the parameters below 5%. The values are presented as absolute in kg and calculated to related costs in Brazilian currency (R$) and American dollar (USD). For this study average exchange rate from that periodwas used (1 USD = 4 R$). Comparative values for unlimited and limited food service have been expressed as absolute value for total waste and mean ± standard deviation (SD) for calculations per day. ANOVA,followed by an LSD post hoc test (SPSS 15.0 for Windows), was usedto compare the differentservices, and the values of p < 0.05 were consideredas statistically significant (a: p < 0.05; b: p < 0>; c: p < 0>).