The Fruit Saver aims at reducing the food waste of fruits and vegetables in supermarkets. This is done both, by slowing the decaying process and alluring customers into buying the more mature products. The system has sensors placed all over the fruit shelf, and is thus able to detect and measure the levels of ethylene, a gas produced during ripening. The sensor system can be implemented independently for each box or compartment containing vegetables or fruits. Since each batch contains products of the same type, that likely have been harvested at the same time and have the same origin, the system monitors the average maturation level of each of these groups. Many functions are provided through interaction with an app, that can be logged in either as Customer or Employee, and behaves differently according to the type of login. Here are some details:

• Should the ethylene levels be too high, it is likely that one or some fruit are already rotting. In this case the system, through an app, summons the supermarket employees to remove them before they spread the mold to healthy products.
• The prices of fruits and vegetables are modified according to the stage of matureness they are on, and the supermarket customers can check and can be notified of these discounts through an app.
• Periodically, and according to the sensor readings, a fan is activated to blow away the ethylene. In fact this gas is known for accelerating the maturation process.

In the first prototype we use only one kind of fruit: banana.

• Sensor: an ethylene sensor.
• Fruit: either a fruit or vegetable that is monitored by the system.
• Fan: the fan positioned into the fruit saver that periodically blows on the fruits.
• The app: the app that comes with the system; it is divided in two parts.
• Customer: the customer that buys the fruits. It is a synonym of Guest.
• App's Guest-section: the section of the app where normal customers can log in, mostly implements notifications about discounts.
• App's Staff-section: the section of the app where supermarket employees can log in, warns them about rotting fruits.

• Customers: the supermarket customers, that can download the guest app and see the discounts.
• Employees: the supermarket employees, that can download the staff app and must get rid of rotting fruits.
• Manager: the supermarket manager, that along with the customers is the one that benefits the most from the system.

1. GST: App's Guest-section functionalities
2. STF: App's Staff-section functionalities
3. FRT: Sensing and reasoning about the fruits
4. PRC: Price settings
5. FAN: Fan settings

GST

1. Notifications (Priority 1): The customers receive notifications on their phone through the guest app. The notification are about convenient prices on products.
2. Notifications based on location (Priority 3): The customers will receive notifications only when they are inside the supermarket. There is no point in sending them to people that are not already planning to go shopping.
3. Setting preferences for fruits (Priority 2): The customers are able to create their own list of "favourite fruits", and will receive just the notifications regarding those. Why would you want to be notified about cabbages on sale if you haven't eaten one in years?
4. Monitoring (Priority 2): The customers are able to keep an eye on the overall situation of the fruits in the supermarket through the guest section of the app.
5. Guest map (Priority 5): This function complements the one above (GST-4). The app includes a map of the supermarket showing where the discounted fruits are located, so that the customers can always know where to go.
6. Notification hours (Priority 2): Guest notifications will only be received if the supermarket is in its opening hours. The default settings of this feature are the default opening hours of the supermarket, but could be modified by the staff through STF-5.

STF

1. Notifications (Priority 1): The staff gets a notification whenever a rotting fruit is detected. The feature reports the code of the shelf where assistance is needed. This can be improved with STF-6.
2. Monitoring (Priority 1): The employees can check through the app the levels of ethylene in various shelves, so that they can better organize their activities or remove rotting fruits beforehand.
3. "I'm going" functionality (Priority 3): The staff app allows the staff to call out to their colleagues whenever they are going to remove a rotting fruit. This is to avoid more than one employee going to the same shelf. Also, this functionality allows to mark out when the issue is solved, since the sensors may take a while to detect that.
4. Manually apply discounts (Priority 5): Should the sensor malfunction or be too imprecise, the employees can manually set the discounts, thus overriding the calculations of the system. This is essentially a backdoor, an emergency feature.
5. Setting default hours (Priority 5): This feature can only be implemented along with GST-2. It allows the staff to decide the default hours of the guest section of the app, with the purpose to have more flexible notifications in case the supermarket has different opening hours than usual.
6. Staff map (Priority 4): Works together with STF-1. The App's Staff Section includes a map of the supermarket that highlights the sector and the shelf where the employee's assistance is needed.

FRT

1. Weghting the fruits (Priority 1): The system lack an "eye" sensor, and thus relies on a scale to estimate the amount of fruits that it is currently monitoring. The total wieght of the products is needed to interpre the ethylene readings and calculate the price (see FRT-3).
2. Sensing the ethylene (Priority 1): The ethylene sensors measure the ethylene amounts in the air. The measurements are periodical and continuous, since the fan would alter the results too much, and notifications follow the measurement's frequency. After all ripening is quite a slow process, and doesn't need godspeed reactions. Since ethylene is a very volatile gas, and disperses quite easily, the sensors are positioned among and beneath the fruits, where it is more dense.
3. Ripeness stages (Priority 1): Fruits produce different amount of ethylene in the various ripeness stages. Given the measurements of ethylene and weight the system estimates the average maturation degree of each fruit. All the other features are functions of the average ripeness stage that is here calculated.

PRC

1. Setting discounts values (Priority 1): Discounts are applied according to the ethylene measurements.
2. Basic LEDs (Priority 1): Given the need to show changing prices, the more practical option is a led display. Nothing fancy, just something that is easily read and doesn't consume much. The price values are taken from a database decided by the manager.
3. Alluring LEDs (Priority 2): The led functionality can be improved by implementing color leds and some flashing pattern of sorts, with the purpose of drawing the attention towards the discounts.

FAN

1. Blowing away the gas (Priority 1): Ethylene is a gas that accelerates the decaying process, and so, with the purpose of preventing the rotting of fruits, a fan blows it away. It is activated periodically to allow periodic and unspoiled sampling of the ethylene levels.

1. Language

   Description: System language is english.

   Area: Usability

2. Android App

   Description: The Android app supports OS versions following 4.4.

   Area: Portability

3. Response Time

   Description: The system response time for price updating and notifications depends on the gas samplings, while the app performance is less than 200/300 ms.

   Area: Efficiency

4. Consumer's internet connection

   Description: All consumers must have a internet connection to use the app.

   Area: Interoperability

5. Internet connection of the system

   Description: In order for the sensors and the app to work properly, it is necessary an internet connection.

   Area: Interoperability

6. Connections between the sensors

   Description: The sensors must have access to a control unit of sorts in order to trasmit data to the central system.

   Area: Interoperability

7. Organizational Requirements

   Description: The sensor layout must be such to allow the installation of several units. Furthermore a database containing specific data about different types of fruits and vegetables should be provided or implememnted.

   Area: Implementation

8. Prototype Restrictions

   Description: The first version of the Fruit Saver will only support one type of fruit. Due to the copious amounts of gas that it usually produces and to its fast maturation, we have chosen to use the banana. In following versions the system may be implememented to support all kinds of climateric fruits (non-climateric fruits don't produce ethylene).

   Area: Implementation