Luis Carlos Cunha Junior

Predicting soluble solid content in intact jaboticaba [Myrciaria jaboticaba (Vell.) O. Berg] fruit using near-infrared spectroscopy and chemometrics

The aim of this study was to evaluate the potential of near-infrared reflectance spectroscopy (NIR) as a rapid and non-destructive method to determine soluble solid content (SSC) in intact jaboticaba [Myrciaria jaboticaba (Vell.) O. Berg] fruit. Multivariate calibration techniques were compared with pre-processed data and variable selection algorithms, such as partial least squares (PLS), interval partial least squares (iPLS), a genetic algorithm (GA), a successive projections algorithm (SPA) and nonlinear techniques (BP-ANN, back propagation of artificial neural networks; LS-SVM, least squares support vector machine) were applied to building the calibration models. The PLS model produced prediction accuracy (R(2)=0.71, RMSEP=1.33 °Brix, and RPD=1.65) while the BP-ANN model (R(2)=0.68, RMSEM=1.20 °Brix, and RPD=1.83) and LS-SVM models achieved lower performance metrics (R(2)=0.44, RMSEP=1.89 °Brix, and RPD=1.16). This study was the first attempt to use NIR spectroscopy as a non-destructive method to determine SSC jaboticaba fruit.

NIRS and iSPA-PLS for predicting total anthocyanin content in jaboticaba fruit.

The aim of this study was to evaluate the potential of the successive projection algorithm for interval selection in partial least squares (iSPA-PLS) together with near-infrared reflectance spectroscopy (NIRS) as a feasible method to determine the total anthocyanin content (TAC) of intact jaboticaba fruit [Myrciaria jaboticaba (Vell.) O. Berg]. A total of 579 jaboticaba fruit were collected in three different harvests in three separate years (2011 and 2013). The correlation coefficients between the predicted and measured TAC were between 0.65 and 0.89, the RMSEPs were 7.55 g kg(-1) and 9.35 g kg(-1) (good accuracy) for prediction set, respectively. The RPD ratios for TAC were in the range of 2.57-3.19 with iSPA-PLS, which showed better predictive performance (acceptable precision). These results suggest that the NIR spectroscopy and wavelength selection (iSPA-PLS) algorithm can be used to determine the TAC of intact jaboticaba fruit.

Quality Evaluation of Shelled and Unshelled Macadamia Nuts by Means of Near‐Infrared Spectroscopy (NIR)

The quality of shelled and unshelled macadamia nuts was assessed by means of Fourier transformed near-infrared (FT-NIR) spectroscopy. Shelled macadamia nuts were sorted as sound nuts; nuts infected by Ecdytolopha aurantiana and Leucopteara coffeella; and cracked nuts caused by germination. Unshelled nuts were sorted as intact nuts (<10% half nuts, 2014); half nuts (March, 2013; November, 2013); and crushed nuts (2014). Peroxide value (PV) and acidity index (AI) were determined according to AOAC. PCA-LDA shelled macadamia nuts classification resulted in 93.2% accurate classification. PLS PV prediction model resulted in a square error of prediction (SEP) of 3.45 meq/kg, and a prediction coefficient determination value (Rp (2) ) of 0.72. The AI PLS prediction model was better (SEP = 0.14%, Rp (2) = 0.80). Although adequate classification was possible (93.2%), shelled nuts must not contain live insects, therefore the classification accuracy was not satisfactory. FT-NIR spectroscopy can be successfully used to predict PV and AI in unshelled macadamia nuts, though.

Conservação de pêssego 'Aurora-1' armazenados sob refrigeração

This work aimed to evaluate the postharvest of peaches cv. Aurora-1 stored under refrigeration. The fruit were harvested in two stages (“mature green” and ripe). The lots were stored at three temperatures (2°C, 6°C, and 12°C), for 35 days and evaluated every seven days for skin color, loss of fresh mass (PMF), firmness (FIR), appearance, titratable acidity (TA), soluble solids (SS), soluble sugar (AS) and reducers (AR), soluble (SP) and total (PT) pectin, and the percentage of pectin solubilization (SOL). The lower storage temperature gave the greatest shelf life and the fruit at mature green stage had better appearance. The PMF showed a gradient of weight loss due to the increase of temperature and the mature green fruit had smaller weight loss at the end of storage for all temperatures, compared to mature. The skin color of the fruit “mature green”, stored at 2°C, had little change, from green-yellow to light yellow, while on temperatures at 6°C and 12°C this gradient was more intense. The same effect was found in ripe peaches. The FIR was affected by temperature, and the lowest temperature changed slowly. The AT for ripe peaches was higher for the mature green. There was no influence of treatments on the contents of SS, AS and AR. Peaches ‘Aurora-1’ showed no chilling injury symptoms and the ones harvested at mature green stage, when stored at 2°C had 35 days of shelf life.ABSTRACT – This work aimed to evaluate the postharvest of peaches cv. Aurora-1 stored under refrigeration. The fruit were harvested in two stages (“mature green” and ripe). The lots were stored at three temperatures (2°C, 6°C, and 12°C), for 35 days and evaluated every seven days for skin color, loss of fresh mass (PMF), firmness (FIR), appearance, titratable acidity (TA), soluble solids (SS), soluble sugar (AS) and reducers (AR), soluble (SP) and total (PT) pectin, and the percentage of pectin solubilization (SOL). The lower storage temperature gave the greatest shelf life and the fruit at mature green stage had better appearance. The PMF showed a gradient of weight loss due to the increase of temperature and the mature green fruit had smaller weight loss at the end of storage for all temperatures, compared to mature. The skin color of the fruit “mature green”, stored at 2°C, had little change, from green-yellow to light yellow, while on temperatures at 6°C and 12°C this gradient was more intense. The same effect was found in ripe peaches. The FIR was affected by temperature, and the lowest temperature changed slowly. The AT for ripe peaches was higher for the mature green. There was no influence of treatments on the contents of SS, AS and AR. Peaches ‘Aurora-1’ showed no chilling injury symptoms and the ones harvested at mature green stage, when stored at 2°C had 35 days of shelf life.Index terms: Prunus persica, harvest stage, cold storage.

Keeping quality of peaches 'Aurora-1' stored under refrigeration

This work aimed to evaluate the postharvest of peaches cv. Aurora-1 stored under refrigeration. The fruit were harvested in two stages (“mature green” and ripe). The lots were stored at three temperatures (2°C, 6°C, and 12°C), for 35 days and evaluated every seven days for skin color, loss of fresh mass (PMF), firmness (FIR), appearance, titratable acidity (TA), soluble solids (SS), soluble sugar (AS) and reducers (AR), soluble (SP) and total (PT) pectin, and the percentage of pectin solubilization (SOL). The lower storage temperature gave the greatest shelf life and the fruit at mature green stage had better appearance. The PMF showed a gradient of weight loss due to the increase of temperature and the mature green fruit had smaller weight loss at the end of storage for all temperatures, compared to mature. The skin color of the fruit “mature green”, stored at 2°C, had little change, from green-yellow to light yellow, while on temperatures at 6°C and 12°C this gradient was more intense. The same effect was found in ripe peaches. The FIR was affected by temperature, and the lowest temperature changed slowly. The AT for ripe peaches was higher for the mature green. There was no influence of treatments on the contents of SS, AS and AR. Peaches ‘Aurora-1’ showed no chilling injury symptoms and the ones harvested at mature green stage, when stored at 2°C had 35 days of shelf life.ABSTRACT – This work aimed to evaluate the postharvest of peaches cv. Aurora-1 stored under refrigeration. The fruit were harvested in two stages (“mature green” and ripe). The lots were stored at three temperatures (2°C, 6°C, and 12°C), for 35 days and evaluated every seven days for skin color, loss of fresh mass (PMF), firmness (FIR), appearance, titratable acidity (TA), soluble solids (SS), soluble sugar (AS) and reducers (AR), soluble (SP) and total (PT) pectin, and the percentage of pectin solubilization (SOL). The lower storage temperature gave the greatest shelf life and the fruit at mature green stage had better appearance. The PMF showed a gradient of weight loss due to the increase of temperature and the mature green fruit had smaller weight loss at the end of storage for all temperatures, compared to mature. The skin color of the fruit “mature green”, stored at 2°C, had little change, from green-yellow to light yellow, while on temperatures at 6°C and 12°C this gradient was more intense. The same effect was found in ripe peaches. The FIR was affected by temperature, and the lowest temperature changed slowly. The AT for ripe peaches was higher for the mature green. There was no influence of treatments on the contents of SS, AS and AR. Peaches ‘Aurora-1’ showed no chilling injury symptoms and the ones harvested at mature green stage, when stored at 2°C had 35 days of shelf life.Index terms: Prunus persica, harvest stage, cold storage.