Pannico, Antonio (2014) Improving hazelnut quality at harvest and non-destructive assessment of post-harvest nut quality. [Tesi di dottorato]


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Item Type: Tesi di dottorato
Resource language: English
Title: Improving hazelnut quality at harvest and non-destructive assessment of post-harvest nut quality
Date: 31 March 2014
Number of Pages: 85
Institution: Università degli Studi di Napoli Federico II
Department: Agraria
Scuola di dottorato: Scienze agrarie e agro-alimentari
Dottorato: Scienze e tecnologie delle produzioni agro-alimentari
Ciclo di dottorato: 25
Coordinatore del Corso di dottorato:
Cirillo, ChiaraUNSPECIFIED
Forlani, MarcelloUNSPECIFIED
Date: 31 March 2014
Number of Pages: 85
Keywords: hazelnut; quality; nut composition; NIR spectroscopy; intracanopy variability; fruit position; foliar fertilization; boron; nutrition;
Settori scientifico-disciplinari del MIUR: Area 07 - Scienze agrarie e veterinarie > AGR/03 - Arboricoltura generale e coltivazioni arbore
Date Deposited: 07 Apr 2014 11:20
Last Modified: 17 May 2017 01:00

Collection description

Italy is the second hazelnut producer country in the world, and more than 30% of the Italian cultivated area is located in Campania (South Italy). Usually hazelnuts (Corylus avellana L.) are sold both in-shell and shelled. In-shell hazelnuts are mainly designed for fresh consumption while shelled ones, are employed, as raw material, in confectionary and bakery food companies. Furthermore, due to its beneficial health attributes, hazelnuts have also been valued by cosmetic and pharmaceutical companies. Nuts are source of bioactive compounds such as plant proteins, essential minerals, vitamin E, unsaturated fatty acids, and polyphenols. Fruit quality has gained a key relevance in the processing industry, since companies are attempting to find useful methods to better characterize their own products. However, hazelnut is still little studied and till now many questions on nut quality improvement need to be still addressed. The general aim of this thesis was to increase the knowledge of factors and techniques that can positively affect hazelnut final quality. Therefore, the thesis was organized in three experiments. In the first experiment the effect of foliar fertilization with nitrogen and micronutrients on yield, nut quality, and kernel composition was evaluated. Thirty ten-year-old hazelnut trees, cv. 'Mortarella' randomly distributed in an private orchard located in Caserta, Southern Italy, were selected. The foliar spray treatments compared were: control (C) (only water), Coryl-Dry 2.5% (CD) (7% CH4N2O, 2% N organic, 0.5% B H3BO3, 0.5% Zn EDTA, 0.05% Fe EDTA) and boron 300ppm (B) (H3BO3). Spraying applications were carried out on mid April, mid May and mid June in 2011, 2012 and 2013. In general, foliar fertilization affected vegetative growth. CD trees showed a higher shoots extension growth, total leaf area, and trunk cross-sectional area than control trees in 2012, while there were no significant effects on yield. Foliar spray significantly improved kernel weight and decreased the incidence of blanks by about 2% compared to control. Differences in fat, protein, and carbohydrate concentration were found in 2012 and 2013 among treatments. In CD and B trees, fat concentration increased from about 60% to 64%, whereas carbohydrate concentration tended to decrease from 23.4% to 19-15.5% compared to control. The total polyphenols content was affected by foliar fertilization in 2013, CD and B trees had a higher values (respectively 153.4 and 147.7 mg/kg) than the control (128.7 mg/kg). Foliar fertilization improved oil composition of the kernels, but fatty acid composition responded differently to nutrients spray. Oleic acid concentration was promoted while palmitic acid concentration was reduced in fertilized plants compared to control trees. Furthermore, CD and B trees were characterized by an increase in the ratio of unsaturated/saturated fatty acids compared to untreated trees. Finally, foliar spray improved lipid stability compared to control, due to higher total polyphenol concentration. The second experiment aimed to study the intra-canopy variability in kernel growth and composition. In August 2013, ten 10-year-old hazelnut trees were selected in the same orchard of the first experiment. Tree canopies were divided in six horizontal layers. Each layer was equally divided into inner zone and outer zone, obtaining 12 canopy sectors. The PAR distribution in each canopy sector was measured on 5 September at nine times of the day (hourly measurements, from 10:30 am to 18:30 pm), by horizontally placing a ceptometer in five different points inside each canopy sector. On 24 September, when fruits were physiologically ripen, five infructescences were separately harvested in each canopy sector of sampled trees, and their the original position (height from the ground) was measured. A sample of fifty nuts per sector was used for qualitative analysis. Canopy position affected kernel fresh and dry weight. Height above the ground and kernel dry and fresh weight resulted linearly and positively related. Fat percentage was found to be similar for all the kernel samples harvested at different heights below 2.00 m, averaging 64%, whereas it decreased linearly at 60% in apical position samples (above 2.0 m). On the contrary, protein and ashes content on percentage increased progressively from lower to higher zone. Furthermore, height above the ground strongly affected fatty acid composition The intermediate productive layer showed higher quantity of oleic acid than bottom and top canopy layer. Among the fatty acid, stearic acid and γ linolenic acid resulted positively related to height above the ground, while palmitoleic acid and linoleic acid were negatively related to it. Finally, the extinction coefficient K232 decreased from 1.6 to 1.35 proceeding from the lowest to the highest canopy position. In the third experiment, the feasibility of NIR spectroscopy in estimating the level of lipid oxidation in unshelled and shelled hazelnuts was investigated. Twenty 5-kg samples of unshelled ‘Mortarella’ hazelnuts, harvested between 2008 and 2012, were stored in a warehouse at room temperature until the beginning of the experiments in January 2013. Five randomly selected whole hazelnuts per batches were measured by NIR spectroscopy on two opposite sides, first as a whole kernel and then as a shelled kernel. After scanning, kernel oil was extracted and fat oxidation was determined. The best results, expressed as coefficient of determination, were obtained for the K232 extinction coefficient for both unshelled (R2=0.79) and shelled (R2=0.85) hazelnuts and also low values for the RMSECV were obtained. The possibility to use the K232 variable as predictor of lipid oxidation in both unshelled and shelled hazelnuts is a commercially valuable result.


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