An attempt to the nondestructive investigation of photo-induced potato postharvest quality degradation – Preliminary results

Abstract

Among improper harvest and/or postharvest storage conditions, the effect of direct sunlight plays an important role in quality degradation of potato resulting in the development of green surface color based on chlorophyll formation associated with the formation of poisonous chemicals – glycoalcaloids – known as α-chaconine and α-solanine. Yellow skinned and fleshed potatoes with or without visible initial marks of green surface color were stored at normal room temperature under direct natural (sun)light conditions for almost two months. The aim of this study was the preliminary investigation of the sunlight induced formation of chlorophyll related compounds in potato indirectly by the detection of chlorophyll development. This attempt was based on nondestructive determination of chlorophyll related spectral and fluorescence indices for both sunlight exposed and unexposed potato sides. For both potato groups the chlorophyll content related DA-index® and chlorophyll fluorescence characteristics (F0, Fm, Fv and Fv/Fm) increased during the storage period representing chlorophyll formation. In the case of Fm, Fv and Fv/Fm values, the yellow samples reached the values of the initial spotted green samples by the 7th–9th days. From this time, the chlorophyll fluorescence values changed only minimally. After storage day 34, in the case of both at day 0 yellow and green spotted potatoes, the sunny side's F0 value was lower than that of shaded side. Close relationship was found between the results of Walz monitoring-PAM (Pulse Amplitude-Modulated) chlorophyll fluorometer and the PSI (Photon Systems Instruments) chlorophyll fluorescence imaging device (e.g. Fv R2 = 0.7226). According to our preliminary results, the Vis/NIR DA-meter®, the monitoring-PAM and the chlorophyll fluorescence imaging fluorometers were found to be suitable nondestructive devices for further investigations concerning the postharvest chlorophyll formation based greening phenomena, which is associated with solanine development in potato.

A Review on Greening and Glycoalkaloids in Potato Tubers: Potential Solutions

“…The measurement of greening is mostly visual observation; 25 however, it can be scientifically measured by colorimeter, 26 fluorimeter, 25 or a visible/nearinfrared (VIS/NIR) DA-meter, which measures color in index of absorbance difference. 27 Total glycoalkaloids are mainly present in the skin and around the eyes 28 of the potato, which is generally called the growing point on potatoes and where sprouts start developing. TGA are not present throughout the potato matrix; however, they are usually accumulated more on the skin than the flesh of the potato.…”

“…Greening of potatoes mostly occurs on the skin or toward the surface, as shown in Figure . The measurement of greening is mostly visual observation; however, it can be scientifically measured by colorimeter, fluorimeter, or a visible/near-infrared (VIS/NIR) DA-meter, which measures color in index of absorbance difference …”

The Use of Chlorophyll Fluorescence as an Indicator of Predicting Potato Yield, Its Dry Matter and Starch in the Conditions of Using Microbiological Preparations

“…This effect is the result of the incidental scattering of light that is not used by the plant in photosynthesis. During photosynthesis, plants absorb light energy through chlorophyll molecules, which are located in chloroplasts-structures responsible for carrying out photosynthesis [14][15][16]. These molecules convert energy into a chemical form, which is then utilized to produce organic compounds like glucose.…”

“…As is well-known, ATP is produced from a phosphate ion (P) and ADP, either through solar energy or the energy released by respiring sugars. ATP is a molecule used to supply energy to other parts of the plant for the accumulation of substances necessary for growth and development such as enzymes, sugars, amino acids, and starch in the reverse reaction: ATP -> ADP + P + energy [14,15].…”

“…The current literature highlights the importance of biopreparations based on EM as a versatile tool in agriculture, environmental protection, food industry, pharmaceuticals, and medicine [1][2][3][4][6][7][8][9][10]13,23,24], and the potential of chlorophyll fluorescence as a tool for monitoring and optimizing plant production [14][15][16]20,21].…”