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A field trial was conducted between 2006 and 2009 in order to quantify the effect of boron (B) application on the yield and quality of chestnuts. The trial was established in an acid soil derived from siliceous schist and two levels of B were applied. Fruit abortion and nut yield per tree were measured, and nut quality parameters and chemical composition of the kernel were determined. Foliar B concentration was 8.6 mg kg−1 in the control trees and 48.4 mg kg−1 in fertilized chestnuts. Boron improved fruit setting and promoted nut production by 77%. In 2008, the occurrence of cold temperatures enhanced the effect of B on fruit setting, which was four-fold, whereas with the normal temperatures of 2009 the increase was lower. The drought of 2009 was responsible for the ruinous chestnut caliber and shell cracking. Boron induced a significant increase in the crude fat of chestnut kernel. [ABSTRACT FROM AUTHOR]

The major aim of this study was to evaluate the effects of industrial processing on the composition of minerals, free sugars, vitamins and pigments in fruits of chestnut cultivars at four stages of industrial processing (A–fresh; B–after 3 months storage at ± 0 °C and relative humidity = 90%; C–after flame peeling at 800 °–1000 °C for 1–2 s; D–after freezing in a tunnel with a CO2 flow at −65 °C for 15–20 min) from two harvest years. Potassium and phosphorous were predominant in the fruits of all cultivars for both harvest years. Calcium, magnesium, iron, zinc and manganese were also present in the fruits. Fruits from both harvest years had a significant content of free sugars, with sucrose predominating, and these sugars were more affected by the processing stage. Significant levels of lutein, lutein esters, γ-tocopherol and vitamin C were also found in the chestnut fruits. Fruit carotenoids and vitamin C significantly decreased during the industrial processing. [ABSTRACT FROM AUTHOR]

This is the first two year study with the major aim of evaluating the effects at the four sequential major stages of industrial processing (A-fresh, B-after storage during 3 months at ±0 °C and RH = 90%, C-after industrial peeling by flame or fire at 800–1000 °C, D-after freezing in a tunnel with a CO2 flow at –65 °C) on the contents of important nutrients in the fruits of four Portuguese (Judia, Longal, Martaínha and Lada) and two European (‘Spanish’–Puga do Bolo, and ‘Italian’– Viterbes) cultivars of Castanea sativa Mill. Fruits were found to contain significant contents of crude energy but low fat. In both harvest years, the interaction cultivar × processing step had the greatest influence on the starch contents while the cultivar factor had a much greater influence on the dry matter content. The fibre contents were more influenced by the processing stage for both harvests years. [ABSTRACT FROM AUTHOR]

The aim of this study was to analyse the effects of industrial processing on the composition of proteins, free amino acids and phenolics in Castanea sativa Mill. fruits of 2 years. The Portuguese cultivars were Judia, Longal, Martaínha and Lada, and the European cultivars were ‘Spanish’ (Puga do Bolo) and ‘Italian’ (Viterbes). At all processing stages the fruits contained low contents of protein (4.1–5.4 g 100 g−1 d.m.). The essential amino acid Thr had the highest values (3.6–10.0 mg 100 g−1 f.w.), while the highest non-essential amino acid was Asn (14.9–36.4 g 100 g−1 f.w.). Total phenolics (6.6–18.3 mg g−1 f.w.) were more significantly affected by the processing stage factor. In 2007 the gallic acid contents were more affected by the processing stage and interaction factors (cultivar × processing stage), whereas the cultivar factor had more of an effect on ellagic acid. Industrial processing has some negative effects, specifically reducing the contents of some amino acids. [ABSTRACT FROM AUTHOR]

Sweet chestnut (Castanea sativa Miller) is a tree species whose edible fruit was a staple food for many centuries until the emergence of potato and cereal crops. Once of great importance for the survival of rural populations, at present there is a renewed interest in this fruit as a nutritious food, partly due being gluten-free. Portugal is one of the major sweet chestnut producing countries and is an important natural habitat for native European chestnut species. In a nutriproteomics approach, the main objective was to describe and evaluate the sweet chestnut germplasm present in Portugal. Globulins of 22 Portuguese sweet chestnut varieties were used as markers of genetic diversity. This characterization showed significant diversity (h = 0.334) among the varieties tested, but also a homonymy problem in varietal identification. Two-dimensional electrophoresis and mass spectrometry were then used to further investigate the chestnut proteome. Most of the proteins were assigned as having functions in nutritional storage activity. The photorespiration protein Rubisco, normally present in photosynthesizing plant parts was also present in the fruit which suggests that the catabolism of this protein is unusual in C. sativa species. Furthermore, the Portuguese varieties have been shown to be good sources of essential amino acids, and particularly the 'Bária' variety showed a balanced profile that meets the recommended dietary requirements of older children, adolescents, and adults. [ABSTRACT FROM AUTHOR]

In the northeast of Portugal there is a tendency to introduce irrigation system on the chestnut orchards but the effect of irrigation on the chestnut’s quality has not been studied yet. This study aims to evaluate the effect of irrigation on the ‘Judia’ cultivar chestnuts quality concerning its chemical composition, fruit size and tastiness. Three treatments were applied during 2015 and 2016: the drip system, the micro-sprinkler system and a non-irrigated treatment. In both years the bigger chestnuts and production were always present in irrigated treatments. Significant differences among treatments were found in ashes, starch, soluble sugars, and crude protein contents in 2015, but in 2016 no significant differences were found. Moreover, the non-irrigated chestnuts were the sweetest but with smaller calibre. The chestnuts from micro-sprinkler were the firmest and they were as sweet as the drip's chestnuts. Results suggest that irrigation, namely with sprinkler system, valorise the chestnuts by increasing its size and keeping its nutritional value and its sensory quality. [ABSTRACT FROM AUTHOR]

Abstract: The chestnut fruit processing generates large amounts of residues as pericarp (outer shell; 8.9–13.5%) and integument (inner shell; 6.3–10.1%). These materials clearly have the potential as sources of valuable co-products. The analyses of the pericarp and integument of four Portuguese chestnut cultivars (Judia, Longal, Martaínha and Lada) revealed significant contents of total phenolics, low molecular weight phenolics (gallic and ellagic acid), condensed tannins and ellagitannins including castalagin, vescalagin, acutissimin A and acutissimin B. The integument tissues had the highest levels of total phenolics and condensed tannins. The most efficient extraction solvent for the total phenolics, total condensed tannins and low molecular weight phenolics (in Longal) was 70:30 acetone:water at 20°C. The pericarp and integument tissues of the cultivar Longal were richest in gallic acid and castalagin. It is clear that these materials could be used for the extraction of valuable phenolics. [Copyright &y& Elsevier]