Battery-less NFC Sensors for the Internet of Things

5Case Study 4: Fruit Ripeness Sensor

5.1. Motivation

The color of food is the first sensation perceived by the consumer that determines its appearance, influencing their subsequent choice. Food color depends on various factors, including the chemical, biochemical, microbial and physical changes that occur during growth, maturation, postharvest handling and processing (Pathare et al. 2013). Therefore, food color can be used as a quality indicator. Color is one of the most widely measured product quality attributes in postharvest handling and in food processing research and industry.

The interest of consumers in organic food, to know its origin and traceability, has grown in recent years. In this context, RFID technology can play an important role in the coming years. Today, the long market chains that affect many types of fruits and vegetables make it difficult to establish the use-by date or recommended consumption date of these products. Consequently, surface color can be a good indicator of the freshness and flavor quality of fresh products. For example, the ripening process of tomatoes is clearly characterized by the evolution of the color on the tomato’s surface – after harvesting, the fruit continues to ripen and its color turns from green to red. Because transport time must be taken into account, tomatoes that are already ripe (red) must be sold to local markets, while green ones can be shipped to customers located at much greater distances (Lee et al. 2011). Color has ...