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Plums are nutraceutically rich and have health-promoting properties. To produce high-quality fruits, it is important to monitor them at harvest. This study illustrates the potential of nondestructive laser-induced fluorescence and confocal micro Raman spectroscopy for monitoring the ripening of plums. The fluorescence profile indicates that as fruit ripens, the intensity of the fluorescence of chlorophyll at 685 and 730 nm decreases with increase in the intensity ratio (F685/F730) of these bands. These observations reveal that as fruit ripens, there is a gradual loss of chlorophyll. In order to get further insight into pigment dynamics, the Raman spectra of the fruit were analyzed. The Raman spectra of pre and post-ripe stages of fruits show that as the fruit ripens, there is a prominent increase in the intensity of anthocyanin bands accompanied by subsequent decrease in the intensity of the carotenoid bands. The spectral analysis reveals that the ripening is associated with a decrease in the chlorophyll and carotenoid content with subsequent increase in anthocyanins. The results of this study highlight the utility of laser-induced fluorescence and confocal micro-Raman spectroscopy for the rapid, sensitive, and nondestructive monitoring of plum ripening. [ABSTRACT FROM AUTHOR]

Underutilized fruits like kadam are bio-reserves of numerous biochemical and minerals and have the potential to be used as food alternatives and supplements to fulfill the needs of malnourished populations. The production of quality fruits needs monitoring throughout the growth and ripening in order to build consumer and industry confidence. The nondestructive optical spectroscopic techniques have immense potential to monitor the growth and ripening indices of the fruits. Hence, this study explores the potential of laser-induced fluorescence and confocal micro Raman spectroscopy for the reliable and cost effective monitoring of growth and ripening of kadam fruits. The analysis of the laser-induced fluorescence measurements reveals that the ripening of the kadam fruits may be monitored by analyzing the fluorescence emission of chlorophyll and carotenoids. The decrease in the intensity of chlorophyll fluorescence accompanied by the increase in the intensity of the carotenoid bands is the characteristic fluorescence signature associated with the ripening of the kadam fruits. Hence, upon the ripening of the fruits, the concentration of chlorophyll decreases considerably with the accumulation of carotenoids. This fact is further complimented by confocal micro Raman measurements, which show that as the fruit ripens, the intensity of carotenoid bands increases dramatically. The observed spectral features may be used by the horticulture scientists and nutritionists to monitor the growth, maturity, and ripening of underutilized fruits like kadam in order to maximize the quality and minimize postharvest losses. [ABSTRACT FROM AUTHOR]

Ixora flowers of different cultivars are widely grown for their esthetic values as they have bright, abundant, and beautiful inflorescence. A derivative of plant origin, especially flowers, possesses a broad spectrum of biological activities; therefore, it is important to explore current techniques and protocols for the isolation, identification, and characterization of these substances. This study explores the utility of nondestructive spectroscopic probes for monitoring the composition and bioprocess in ixora flowers. The various cultivars of ixora flowers having dark red, dark pink, light pink, peach, orange, and yellow flowers have been collected, and their absorption, fluorescence, and scattering spectral signatures have been acquired using ultraviolet-visible, laser-induced fluorescence and confocal micro Raman spectroscopy. The pre-processing and spectral analysis reveal that biochemicals present in dark red, dark pink, light pink, orange, and peach ixora flowers include flavonoids, phenolic compounds, anthocyanins, and carotenoids of varying concentrations, while the yellow flowers are abundant in carotenoids. The spectral signatures obtained in this study open new avenues for monitoring the substances of plant origin in a nondestructive, rapid, robust, and sensitive way without high operational costs. [ABSTRACT FROM AUTHOR]

Climacteric fruits such as papaya are characterized by changes in the pigment composition during fruit ripening. Therefore, information on the degree of fruit ripeness with respect to the pigment composition using proper monitoring tools is important to growers for determining the appropriate harvest time associated with best quality. This study is aimed at exploring the applicability of spectroscopic probes such as laser-induced fluorescence (LIF) and confocal Raman microspectroscopy for the nondestructive, extraction free and rapid evaluation of pigment changes associated with the growth and ripening of papaya fruits. The laser-induced fluorescence spectra of the papaya show that as the fruit ripening progresses, there is a decrease in intensity of the chlorophyll bands with a simultaneous increase in intensity of carotenoid bands. This phenomenon can be regarded as a characteristic feature of the ripening of papaya. To obtain additional insight about the carotenoid dynamics during ripening, confocal Raman microspectroscopy has been utilized. The Raman spectra show strong spectral signature of carotenoids in both pericarp and mesocarp whose intensity increases as the fruit ripens. In addition, the bands of carotenoids are more prominent in the spectra of the mesocarp than in the pericarp. These facts are supported by the quantitative estimation of pigments in the papaya fruits by ultraviolet-visible spectroscopy. The determined spectral signatures can be used as indices for effective monitoring of ripening of fruits and commercial application for the phenotyping of important plant parts, screening, grading, shelf life estimation and quality standardization. [ABSTRACT FROM AUTHOR]

The present study aims to investigate the interactions of zinc oxide nanoparticles and copper oxide nanoparticles with the major photosynthetic pigment chlorophyll using ultraviolet-visible, steady state, and time resolved laser induced fluorescence spectroscopy. The steady state fluorescence measurements show that zinc oxide and copper oxide nanoparticles quench the fluorescence of chlorophyll in concentration-dependent manner. The Stern-Volmer plot for the chlorophyll-zinc oxide nanoparticles is linear, and the value of quenching constant has been observed to increase with temperature indicating the possibility of dynamic quenching. A decrease in the lifetime of chlorophyll with increase in the concentration of zinc oxide nanoparticles confirms the involvement of dynamic quenching in the chlorophyll–zinc oxide nanoparticle interaction. In the case of copper oxide nanoparticles, the Stern-Volmer plot deviates from linearity observed in the form of upward curvature depicting the presence of both static and dynamic quenching. In addition, the lifetime of chlorophyll decreases with increase in the concentration of copper oxide nanoparticles displaying the dominance of dynamic quenching in the chlorophyll-copper oxide nanoparticle interaction. The decrease observed in the value of binding constant with increasing temperature and negative values of change in enthalpy, entropy, and Gibb's free energy indicates that van der Waal and hydrogen bonding are the prominent forces during the interaction of chlorophyll with both zinc oxide and copper oxide nanoparticles and that the process is spontaneous and exothermic. The interaction of zinc oxide and copper oxide nanoparticles with chlorophyll occurs through electron transfer mechanism. The obtained results are useful in understanding the sensitization processes involving chlorophyll and zinc oxide and copper oxide nanoparticles. [ABSTRACT FROM AUTHOR]

Widespread commercial application of titanium dioxide nanoparticles leads to their dispersion in the environment and inevitable interaction with living organisms. Their presence necessitates the monitoring of nanoparticle interactions with plants using advanced techniques that are capable of noninvasively and sensitively estimating the changes involved in the biochemical profile. The current study aims to investigate the effects of titanium dioxide nanoparticles on biochemicals of wheat leaves using label free, nondestructive, rapid, sensitive, and advanced spectroscopic probes: laser induced fluorescence and attenuated total reflectance Fourier transform infrared spectroscopy coupled with multivariate analysis. The fluorescence and infrared spectra of control and titanium dioxide nanoparticle treated wheat leaves were acquired in the region from 400 to 800 nm and 4000 to 485 cm−1. The treatment of titanium dioxide nanoparticles decreases the chlorophyll content and the concentrations of cellulose, hemicellulose, xyloglucans, pectin, and lignin indicating interferences in the biosynthesis and structure of cell walls of the wheat leaves. The level of amide I, carbonyl, and methylene groups also increases following the treatment of titanium dioxide nanoparticles indicating lipid and protein peroxidation and the accumulation of carbonyl compounds. The changes in the integrated area ratios of the amide II/amide I, carbonyl/methyl, and methylene/amide II bands demonstrate disorder in the membrane integrity. This study establishes the efficiency of noninvasive, label-free, and rapid protocols based on attenuated total reflectance Fourier transform infrared and laser induced fluorescence to monitor the interactions of nanoparticles with plants at early stage of plant growth before visual signs of toxicity appear. [ABSTRACT FROM AUTHOR]

This study explores the application of spectroscopic techniques (laser induced fluorescence, Raman and attenuated total reflectance Fourier transform infrared) coupled with principal component analysis for the nondestructive, extraction free and rapid evaluation of biochemical changes associated with ripening of chili peppers at four stages (mature, pre-ripe, ripe and post-ripe). The analysis of the fluorescence spectra of the exocarp of chili pepper shows a decrease in the intensity of chlorophyll bands at 685 and 735 nm and an increase in the intensity of carotenoid fluorescence bands at 490–500 nm and 565–580 nm with progress in the ripening stages. These changes are regarded to be significant phenotypic markers for the ripening of chili peppers. The observed changes in the position of carotenoid bands in Raman spectra at 1004, 1156, 1188, and 1524 cm−1 with increase in their intensity indicating the accumulation of carotenoids and change in the carotenoid composition from β-carotene in the mature chilis to capsanthin in the ripe chilis. In addition, the infrared spectra show changes in the carbohydrates, amide II, amide I and cutin at various stages of ripening. Also, the variation in the position of pectin bands indicates change in its molecular mass with decreasing content. The determined spectral signatures can be used as biomolecular index for effective monitoring of the ripening of chili peppers. The commercial application of noninvasive spectroscopic probes will be advantageous for the phenotyping of economically important plant parts, screening, grading, shelf life estimation and quality standardization. [ABSTRACT FROM AUTHOR]

The aim of this study is to evaluate the biochemical changes in the leaves of wheat seedlings exposed to gold nanoparticles (AuNPs) nondestructively and rapidly using attenuated total reflectance Fourier transform infrared spectroscopy and laser-induced fluorescence. The 18 nm size gold nanoparticles are synthesized by citrate reduction. For analyzing the effect of gold nanoparticles on wheat seedlings, the treatment of gold nanoparticles was applied to the seedlings through roots and following the spectroscopic measurement of biochemical signatures. The laser-induced fluorescence measurement has been performed to access the effect of gold nanoparticles on the chlorophyll concentration of wheat seedlings. The decrease in the fluorescence intensity and the fluorescence intensity ratio on the treatment of gold nanoparticles indicates increase in the concentration of chlorophyll in the leaves of wheat seedlings. The attenuated total reflectance Fourier transform infrarred spectroscopy in combination with principal component analysis has been used to visualize the biochemical changes in the cellulose, hemicellulose, pectin, lignin, amino acids, proteins, and lipid of the leaves of wheat seedlings by recording infrared spectra in the region from 4000 to 400 cm-1. Principal component analysis applied to the preprocessed infrared data clearly distinguishes the spectral variability between control and gold nanoparticle treated seedlings. The study shows that exposure of gold nanoparticles increases the concentrations of cellulose, hemicelluloses, pectin, and lignin in the leaves of wheat seedlings. The increase in these chemicals indicates the modulation of cell walls of the wheat seedlings by the gold nanoparticle treatment. The exposure to gold nanoparticles also enhances the expression of lipid and proteins in the leaves of wheat seedlings. [ABSTRACT FROM AUTHOR]

In the present investigation, attempts have been made to obtain the spectral signature of the fruit jamun and to estimate the changes in biochemical composition that take place in the process of ripening of the fruits. The changes in exocarp, mesocarp, and seed of the fruit in raw and ripe stages have been investigated with the help of label-free, nondestructive, and rapid techniques: laser-induced fluorescence and attenuated total reflectance Fourier transform infrared spectroscopy. For this, the fluorescence spectra of the different parts (exocarp, mesocarp, and seed) of the raw and ripe fruits of jamun excited by 405 nm violet diode laser have been recorded in the spectral region 400–900 nm. The spectrum shows the spectral signature of anthocyanin, flavonoids, carotenoid, and chlorophyll. The observed decrease in the intensity of chlorophyll bands and simultaneous increase in the intensity of anthocyanin and carotenoid bands is regarded as indicator of the ripening of the fruit of jamun. Also, attenuated total reflectance Fourier transform infrared spectra have been recorded in the spectral region 4000–485 cm−1for the identification of functional groups associated with different biochemical altered during ripening process of the fruits of jamun. The analyses of the recorded infrared spectra show the presence of carbohydrates, cell wall components, phenolic compounds, nucleic acid, and amide. The quantitative estimation of the biochemical content in the different parts of jamun fruit during the ripening process has been done through calculating the area of the band by curve fitting. The determined spectral signatures can be utilized for the effective monitoring of jamun fruit. [ABSTRACT FROM AUTHOR]