PLS, iPLS, GA-PLS models for soluble solids content, pH and acidity determination in intact dovyalis fruit using near-infrared spectroscopy.

BACKGROUND: Dovyalis species Dovyalis abyssinica Warb. and Dovyalis hebecarpa Warb. were introduced into Brazil, but the fruit quality of these species is not appropriate for fresh consumption due to their high titratable acidity (TA) and low soluble solids content (SSC). With the selection of new D. abyssinica clones with lower acidity and the hybridization of these two dovyalis species (D. abyssinica and D. hebecarpa) the fruit quality improved and the better physical-chemical characteristics make them more suitable for fresh consumption. The objective of this study was to develop partial least squares (PLS) models using near infrared spectroscopy (NIRS) for the determination of SSC, TA and pH in intact dovyalis hybrid fruit (D. abyssinica Warb. × D. hebecarpa Warb.). RESULTS: The best SSC prediction model was developed with PLS regression (root mean square error of prediction (RMSEP ) of 0.71 °Brix, prediction data set (RP 2 ) of 0.74 and residual predictive deviation (RPD) of 2.82). Although interval PLS was tested, genetic algorithm PLS performed better for TA (RMSEP of 4.8 g kg-1 , RP 2 of 0.40, and RPD of 1.67), and for pH (RMSEP of 0.03, RP 2 of 0.90, and RPD of 6.67). CONCLUSION: NIRS can be used as a non-destructive method to determine quality parameters in intact dovyalis hybrid fruit. © 2018 Society of Chemical Industry.

Changes in the quality of jaboticaba fruit (Myriciaria jaboticaba (Vell) Berg. cv. Sabará) stored under different oxygen concentrations.

BACKGROUND: Jaboticaba (Myriciaria jaboticaba (Vell) Berg.) is a highly perishable Brazilian berry with a shelf life of only 2 days under ambient conditions. Low temperatures and controlled atmosphere (CA) have been used to extend the shelf life of perishable fruit. Thus the aim of this study was to determine the effect of CA with varying concentrations of oxygen (1, 5, 10, 15 and 21 kPa) during cold storage (12.5 °C) of 'Sabará' jaboticaba fruit. RESULTS: Atmospheres with lower oxygen concentrations (1 and 5 kPa O(2) ) significantly reduced jaboticaba respiration rate. Fruit stored under these conditions had higher L values, and titratable acidity (TA), and lower ratios of soluble solids content (SSC)/TA. However, at the lowest concentration of oxygen (1 kPa O(2) ), firmness decreased markedly compared to fruits stored at higher O(2) levels (P < 0.05). After only 2 days of storage at ambient temperature jaboticaba received a score of 1.6 (dislike strongly - 1) compared to fruit stored under CA, which scored 7.4 (like moderately - 7). After 9 days of storage, fruit from all treatments remained above the limit of acceptability (score 5) and were rated as 6.2. With respect to appearance, statistical differences between treatments were not observed. The total anthocyanin content was not affected by oxygen concentration but decreased 40.4% during CA storage. CONCLUSION: 'Sabará' jaboticaba fruit can be satisfactorily stored under atmospheres containing 5-21 kPa O(2) at 12.5 °C for up to 6 days.