Non-destructive detection of tomato maturity

Tomatoes (Solanum lycopersicum) are the most widely grown vegetable fruit in the world with an important contribution to a healthy diet. They are consumed in diverse ways: raw or cooked while still maintaining their nutritive value. The taste of a tomato can range from sweet to acidic, and can vary depending on the variety of tomato and maturity stage. Visible and near infrared spectroscopy is rapid, convenient and low cost method for detection of fruit quality. The aim of the study is to evaluate the suitability of non-destructive methods for detecting the maturity of tomatoes. Tomatoes were grown in a commercial greenhouse “Mežvidi” of Ltd “Latgale vegetable logistics” and harvested at five stages of ripeness (green, breaker (physiological maturity), turning, light red/yellow (commercial maturity), red/orange (full ripen) were used in experiments. Three tomato varieties orange ‘Bolzano F1’, red-fruited ‘Encore’ and brown-fruited ‘Chokomate F1' were analysed. Content of carotenoids (lycopene, carotene), chlorophylls, acidity and soluble solids are analysed biochemically. Taste index and maturity index were calculated using soluble solids content and acidity. Reflectance spectrums (350–2500 nm) were obtained with spectroradiometer RS-3500. The results proved that the best indicator of ripeness is the colour of the fruit. It is impossible to objectively determine the taste of the fruit by non-destructive methods. Non-destructive methods are suitable for single-coloured fruits (‘Bolzano’ and ‘Enkore’), but for the brown-fruited tomato variety, where the color is determined by both lycopene and chlorophyll, it is more difficult to identify the degree of ripeness. Indices for determining fruit maturity have been developed.