Non-destructive and quantitative determination of O2 concentration of intact pome fruit using gas in scattering media absorption spectroscopy (GASMAS) in transmittance mode

Pome fruits, including apple and pear, are among the most widely cultivated fruits in Europe. These climacteric fruits exhibit faster respiration and an increased ethylene production at the onset of ripening, which can result in rapid ripening, senescence, and decreased storage life. To prevent this, pome fruits are typically stored in a controlled atmosphere (CA) where a decreased level of O2 and a slightly increased level of CO2 are maintained, together with lower temperatures, to reduce the fruit's metabolic activity. It is crucial to maintain an optimal level of O2 in CA storage and therefore it would be beneficial to determine the lowest internal O2 concentration below which off-flavours or hypoxia-related storage disorders would occur. This concentration can then be related to that of the storage atmosphere. Hereto, knowledge of the internal O2 concentration is essential. Conventional techniques for sensing internal O2 concentration in fruit are often destructive and can produce measurement artifacts, limiting their application in the fruit post-harvest domain. Instead, the promising Gas in Scattering Media Absorption Spectroscopy (GASMAS) method can offer a non-invasive alternative for measuring O2 concentrations within porous scattering media, such as fruit. This PhD research was focused on optimization, validation, and evaluation of GASMAS O2 sensor as a fast and non-destructive method for measuring the internal O2 concentration in intact pome fruit, focusing on apple and pear.