Chemical and biochemical characterisation of an IGP ecotype chestnut subjected to different treatments

Heavy metal contamination and health risk evaluation of chestnut (Castanea sativa Miller) consumed in Turkey

This study was performed to determine heavy metals and metalloids in twenty-eight chestnut (Castanea sativa Miller) samples consumed in Turkey by inductively coupled plasma optical emission spectrometry and evaluate health risks for humans through the consumption of chestnut samples. The concentrations of Cd, Cr, Co, Cu, Fe, Pb, Mn, Ni and Zn analyzed in chestnut samples varied from 537 to 635, 608 to 5333, 347 to 972, 207 to 8619, 12,739 to 86,310, 278 to 7549, 8676 to 67,622, 1068 to 18,661 and 3625 to 12,876 µg/kg (dry weight), respectively. The concentrations of Cd and Pb were above the maximum limits determined by the Turkish Food Codex. Healthy risks caused by the heavy metals in the consumed chestnut samples were evaluated by estimating the average daily intake of metal, health risk index (HRI), and total HRI. These results revealed that there is no possible health risk to consumers due to the intake of chestnut samples studied under the current consumption rate.

Natamycin Has an Inhibitory Effect on Neofusicoccum parvum, the Pathogen of Chestnuts

This research aimed to investigate natamycin's antifungal effect and its mechanism against the chestnut pathogen Neofusicoccum parvum. Natamycin's inhibitory effects on N. parvum were investigated using a drug-containing plate culture method and an in vivo assay in chestnuts and shell buckets. The antifungal mechanism of action of natamycin on N. parvum was investigated by conducting staining experiments of the fungal cell wall and cell membrane. Natamycin had a minimum inhibitory concentration (MIC) of 100 μg/mL and a minimum fungicidal concentration (MFC) of 200 μg/mL against N. parvum. At five times the MFC, natamycin had a strong antifungal effect on chestnuts in vivo, and it effectively reduced morbidity and extended the storage period. The cell membrane was the primary target of natamycin action against N. parvum. Natamycin inhibits ergosterol synthesis, disrupts cell membranes, and causes intracellular protein, nucleic acid, and other macromolecule leakages. Furthermore, natamycin can cause oxidative damage to the fungus, as evidenced by decreased superoxide dismutase and catalase enzyme activity. Natamycin exerts a strong antifungal effect on the pathogenic fungus N. parvum from chestnuts, mainly through the disruption of fungal cell membranes.

A Joint Approach of Morphological and UHPLC-HRMS Analyses to Throw Light on the Autochthonous 'Verdole' Chestnut for Nutraceutical Innovation of Its Waste

Nowadays, chestnut by-products are gaining a lot of interest as a low-cost raw material, exploitable for developing added-value products. This is in line with suitable chestnut by-products' management, aimed at reducing the environmental impact, thus improving the chestnut industry's competitiveness and economic sustainability. In this context, with the aim of valorizing local cultivars of European chestnuts (Castanea sativa Mill.), our attention focused on the Verdole cultivar, which has been characterized by using the UPOV guidelines for its distinctness, homogeneity, and stability. After harvesting, Verdole chestnuts were properly dissected to collect the outer and inner shells, and episperm. Each chestnut part, previously crushed, shredded, and passed through diverse sieves, underwent ultrasound-assisted extraction. The extracts obtained were evaluated for their total phenolic, flavonoid, and tannin content. The antiradical capacity by DPPH and ABTS assays, and the Fe(III) reducing power, were also evaluated. Although all the samples showed dose-dependent antioxidant efficacy, plant matrix size strongly impacted on extraction efficiency. LC-HRMS-based metabolic profiling highlighted the occurrence of different polyphenol subclasses, whose quantitative ratio varied among the chestnut parts investigated. The outer shell was more chemically rich than inner shell and episperm, according to its pronounced antioxidant activity. The polyphenol diversity of Verdole by-products is a resource not intended for disposal, appliable in the nutraceutical sector, thus realizing a new scenario in processing chestnut waste.

Antioxidant Activity, Total Phenolic Content and Total Flavonoid Content in Sweet Chestnut (Castanea sativa Mill.) Cultivars Grown in Northwest Spain under Different Environmental Conditions

The sweet chestnut fruit has always had great importance in the southern European countries. Chestnut production is an important source of income and a crop of high environmental value thanks to its role in soil protection. It is also a good food with enormous potential for various aspects of health because of its nutritional qualities. The quality of sweet chestnuts is affected by various factors, such as climatic conditions and cultivation inputs. It is very important to recognize the impacts of climate on chestnut fruits, to improve our current understanding of climate-chestnut interconnections. The current study investigated and compared the antioxidant activity and the total phenolic and flavonoid contents of different cultivars of chestnuts grown in different geographic areas of northwest Spain. The results obtained with three antioxidant capability assays (DPPH, ABTS and FRAP assays) were highly correlated. All the samples had high antioxidant capacity and high total phenolic and total flavonoid contents, which depended both on cultivar and growth region. Ventura variety, harvested in the coldest environments, presented the highest values of antioxidant activity (IC50DPPH = 34.5 g/L), total phenolic content (131.84 mg equivalent of gallic acid/100 g FW) and total flavonoids (7.77 mg eq. catechin/100 g). The variations in the antioxidant capacity, total phenolic and total flavonoid contents of different cultivars, and their associations with climatic environmental factors, revealed the significant impacts of these factors on the synthesis of specialized metabolites and on the nutraceutical potential of chestnuts. The results can provide valuable information for selection of the cultivar and the cultivation conditions of the chestnut, in order to obtain chestnuts with high-quality bioactive characteristics.

Polyphenol Profiling of Chestnut Pericarp, Integument and Curing Water Extracts to Qualify These Food By-Products as a Source of Antioxidants

Plant polyphenols have beneficial antioxidant effects on human health; practices aimed at preserving their content in foods and/or reusing food by-products are encouraged. The impact of the traditional practice of the water curing procedure of chestnuts, which prevents insect/mould damage during storage, was studied to assess the release of polyphenols from the fruit. Metabolites extracted from pericarp and integument tissues or released in the medium from the water curing process were analyzed by matrix-assisted laser desorption ionization-time of flight-mass spectrometry (MALDI-TOF-MS) and electrospray-quadrupole-time of flight-mass spectrometry (ESI-qTOF-MS). This identified: (i) condensed and hydrolyzable tannins made of (epi)catechin (procyanidins) and acid ellagic units in pericarp tissues; (ii) polyphenols made of gallocatechin and catechin units condensed with gallate (prodelphinidins) in integument counterparts; (iii) metabolites resembling those reported above in the wastewater from the chestnut curing process. Comparative experiments were also performed on aqueous media recovered from fruits treated with processes involving: (i) tap water; (ii) tap water containing an antifungal Lb. pentosus strain; (iii) wastewater from a previous curing treatment. These analyses indicated that the former treatment determines a 6–7-fold higher release of polyphenols in the curing water with respect to the other ones. This event has a negative impact on the luster of treated fruits but qualifies the corresponding wastes as a source of antioxidants. Such a phenomenon does not occur in wastewater from the other curing processes, where the release of polyphenols was reduced, thus preserving the chestnut’s appearance. Polyphenol profiling measurements demonstrated that bacterial presence in water hampered the release of pericarp metabolites. This study provides a rationale to traditional processing practices on fruit appearance and qualifies the corresponding wastes as a source of bioactive compounds for other nutraceutical applications.

Total Phenol Content and Antioxidant Activity of Different Celta Pig Carcass Locations as Affected by the Finishing Diet (Chestnuts or Commercial Feed)

The objective of this research was to evaluate the total phenol content, total flavonoids, and antioxidant activity of chestnuts (Castanea sativa Mill.) and commercial feed employed in the finishing diet of the Celta pig breed and analyze the effect of the feeding (chestnuts vs. commercial feed) in the finishing diet on total phenol content and antioxidant activity of Longissimus thoracis et lumborum, Psoas major, and Biceps femoris muscles and liver of the Celta pig breed. The antioxidant activity of the feed and animal tissue was investigated using three antioxidant methods (2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, 2-2'-Azino-di-[3-ethylbenzthiazoline sulfonate] (ABTS) radical scavenging activity, and ferric reducing antioxidant power (FRAP) assay). The determination of the total phenol content and total flavonoids showed that chestnut had a significantly lower concentration than commercial feed in these compounds (130.00 vs. 312.89 mg gallic acid equivalents/100 g fresh weight and 8.58 vs. 32.18 mg catechin equivalents/100 g fresh weight, respectively). However, the results displayed that chestnuts had a higher antioxidant activity when compared with the commercial feed through the DPPH and ABTS methods (1152.42 vs. 957.33 µg Trolox equivalents/g fresh weight, and 9379.74 vs. 7613.44 µg Trolox equivalents/g fresh weight, for DPPH and ABTS assay, respectively), while the antioxidant activity measured by the FRAP assay turned out to show higher values for commercial feed (1777.49 and 1946.09 µmol Fe2+/100 fresh weight for chestnut and commercial feed, respectively), although significant differences were only found in the ABTS assay. On the other hand, the present study found that chestnut significantly reduces the total phenol content and declines the antioxidant activity of Longissimus thoracis et lumborum, Psoas major, and Biceps femoris muscles and liver of the Celta pig breed. Finally, it has been found that liver is the location that has the best antioxidant characteristics compared to any muscle, regardless of diet utilized.

Effect of Steaming Processing on Phenolic Profiles and Cellular Antioxidant Activities of Castanea mollissima

The intention of this study was to investigate the effect of steaming processing on phenolic profiles and antioxidant activities in chestnuts. Steaming processing at different times and temperatures depicted diverse impacts on free and bound fractions. Though, bound phenolics were stable but long time steaming at higher temperatures tended to improve the levels of phenolics, flavonoids as well as antioxidant activities in chestnut kernels, by up to 60.11% of the original value. Seven phenolic compounds including ferulic acid, chlorogenic acid, gallic acid, vanillic acid, syringate, p-coumaric acid and quercetin were found to change during thermal processes. Significant relationships (p < 0.05) were identified between total phenolics and total antioxidant activities. However, the consistency of chlorogenic acid (p < 0.01) only with cellular antioxidant activity indicated poor bio-accessibility of the phytochemicals in chestnuts. However, this situation could be partly improved by steaming. Steaming could improve the cellular accessibility of free phytochemicals, particularly, increasing the bio-accessibility by 41.96%. This study provided valuable information on dynamic changes of phenolic profiles and antioxidant activity of chestnuts under a steaming process, which could offer possible guidance for the chestnut processing industry in the future.

Chestnut Drying Is Critical in Determining Aspergillus flavus Growth and Aflatoxin Contamination

Chestnut drying is used to prevent postharvest losses and microorganism contamination during storage. Several studies reported the contamination by aflatoxins (AFs) produced by Aspergillus spp. in chestnuts. The effect of drying temperatures (from 30 to 50 °C) was evaluated on the growth of A. flavus and the production of aflatoxins in chestnuts. The influence of the treatment on the proximate composition, the total phenol content and antioxidant activity of chestnuts was considered. Fungal colonization was observed on the nuts dried at 30, 35, and 40 °C; the incidence was lower at 40 °C. The highest concentrations of AFB₁ and AFB₂ were produced at 40 °C. No aflatoxins were detected at 45 or 50 °C. At 40 °C A. flavus was under suboptimal conditions for growth (a_w 0.78), but the fungus was able to synthesize aflatoxins. As the temperatures applied increased, the total phenol content increased, while the antioxidant activity decreased. A drying treatment at 45 °C for seven days (a_w 0.64) could be a promising method to effectively control both the growth of aflatoxigenic fungi and the production of aflatoxins. This study provides preliminary data useful to improve the current drying conditions used in chestnut mills, to reduce both fungal growth and aflatoxin production.

Effect of natural antioxidants on physicochemical properties and lipid stability of pork liver pâté manufactured with healthy oils during refrigerated storage

This study aimed to evaluate the effect of natural antioxidants in pork liver pâté manufactured with the combination of pork backfat, fish oil and olive oil. Phenolic composition of beer residue extract (BRE), chestnut leaves extract (CLE) and peanut skin extract (PSE) were identified and quantified. Four batches of pork liver pâté were produced: control, BRE, CLE and PSE. Pork liver pâté was evaluated for proximate composition, pH, instrumental colour, free fatty acid content, lipid-derived volatile compounds and lipid oxidation. The major compounds of BRE were benzoic acid and catechin (1.79 and 1.51 mg/L, respectively), in CLE were ellagic and gallic acid (10.26 and 2.70 mg/100 g fresh weight) and in PSE was catechin (20.66 mg/100 g dry weight). Proximate composition was similar for all batches. The pH values were not influenced by any natural antioxidant. Colour parameters were affected by storage time but slight differences were observed among batches. Lipid stability (TBARS and lipid-derived volatile compounds) was not remarkably affected by addition of natural extracts.

Effect of natural antioxidants in Spanish salchichón elaborated with encapsulated n-3 long chain fatty acids in konjac glucomannan matrix

The effect of natural antioxidants on physicochemical properties, lipid and protein oxidation, volatile compounds and free fatty acids (FFA) were determined in Spanish salchichón enriched with n-3 fatty acids encapsulated and stabilized in konjac matrix. Phenolic compounds of beer residue extract (BRE), chestnut leaves extract (CLE) and peanut skin extract (PSE) were also identified and quantified. Five batches of salchichón were prepared: control (CON, without antioxidants), butylated hydroxytoluene (BHT), BRE, CLE and PSE. The main phenolic compounds were catechin and benzoic acid for BRE, gallic acid and catechin for CLE and catechin and protocatechuic acid for PSE. Statistical analysis did not show significant differences on chemical composition among treatments. Reductions in luminosity (P<0.05) and pH (P<0.001) were observed with the CLE batch, whereas the other colour parameters were not affected by the addition of natural antioxidants. Finally, the inclusion of antioxidants (P<0.001) decreased the hexanal content, whereas the FFA content increased by the addition of natural extracts.

Castanea sativa by-products: a review on added value and sustainable application

Castanea sativa Mill. is a species of the family Fagaceae abundant in south Europe and Asia. The fruits (chestnut) are an added value resource in producing countries. Chestnut economic value is increasing not only for nutritional qualities but also for the beneficial health effects related with its consumption. During chestnut processing, a large amount of waste material is generated namely inner shell, outer shell and leaves. Studies on chestnut by-products revealed a good profile of bioactive compounds with antioxidant, anticarcinogenic and cardioprotective properties. These agro-industrial wastes, after valorisation, can be used by other industries, such as pharmaceutical, food or cosmetics, generating more profits, reducing pollution costs and improving social, economic and environmental sustainability. The purpose of this review is to provide knowledge about the type of chestnut by-products produced, the studies concerning its chemical composition and biological activity, and also to discuss other possible applications of these materials.

Energetic and biochemical valorization of cork boiling wastewater by anaerobic digestion

BACKGROUND

In addition to energy benefits, anaerobic digestion offers other interesting advantages. The cork industry is of great environmental, economic and social significance in the western Mediterranean region, with Portugal being the world-leading producer and exporter. Cork boiling wastewater (CBW) is a toxic and recalcitrant organic effluent produced by this sector, which constitutes a serious environmental hazard. However, there is no documented research on anaerobic treatment/valorization performed with this effluent. The work presented here was developed with the aim to use the anaerobic digestion process to convert the CBW polluting organic load into an energy carrier gas and valuable molecules for industry.

RESULTS

No lag phases were observed and a methane yield of 0.126 to 0.142 m(3) kg(-1) chemical oxygen demand (COD)added was registered in the mesophilic consortium experiments carried out in batch flasks at 37 ± 1°C. Anaerobic digestion can be advantageously connected to ultrafiltration or electrochemical processes, due to the following: 1) reduction of ellagic acid content and consequent decrease of CBW viscosity; and 2) increase in conductivity after the anaerobic process, avoiding the electrolyte application of the electrochemical process. The improvement of several CBW biochemical features shows that anaerobic digestion may provide additionally useful molecules. The rise in concentration of some of these compounds, belonging to the benzoic acid family (gallic, protocatechuic, vanillic and syringic acids), is responsible for the increase of antiradical activity of the phenolic fraction. Additionally, some enzymatic activity was also observed and while the laccase activity increased in the digested effluent by anaerobiosis, xylanase was formed in the process.

CONCLUSIONS

The multidisciplinary approach adopted allowed the valorization of CBW in terms of energy and valuable biomolecules. By exploiting the anaerobic digestion process potential, a novel methodology to toxic and recalcitrant cork processing wastewater was developed.

Volatile fingerprinting of chestnut flours from traditional Emilia Romagna (Italy) cultivars

The volatile profile of nine monocultivar chestnut flours, obtained from fruits grown in Italy (Parma province), was characterised by a head-space solid-phase microextraction (HS-SPME) coupled with GC-MS technique. The volatile fraction was composed of 44 main compounds belonging to different classes, mainly aldehydes, ketones, alcohols, furans and terpenes. Aldehydes, in particular hexanal, are the most abundant components. In order to better understand the origin of the different volatile compounds during the drying and milling processes, samples of fresh fruit were also analysed by the same technique and the data obtained were statistically and critically compared in order to get a picture of the volatile evolution in chestnut from fresh fruit to flour. Finally, the nine monocultivar flours were chemometrically classified on the basis of the main odour descriptors associated with the volatile fingerprinting.