Processing of pistachio nuts

New mechanical procedures for processing pistachio nuts make economical preparation for marketing possible in the United States. These new developments include mechanical dehulling, methods for separating empty nuts from those with well developed kernels, and methods for separating split nuts from those with closed shells.     

Toxic aspergilli from pistachio nuts

Pistachio nut samples taken during various stages of development from orchards in Iran, showed that contamination with fungi occurred mainly during the later stages of nut development. Members of the genera Aspergillus and Penicillium occurred most frequently. Of the Aspergilli, the species A. niger, A. flavus and A. fischeri var. spinosus occurred most frequently, followed by A. terreus, A. tamarii and A. nidulans. Twenty-two isolates comprising 13 species were tested for toxicity to ducklings. Isolates of known toxic fungi included A. flavus, A. niger, A. parasiticus, A. ochraceus, A. versicolor, A. nidulans and A. terreus. The toxicity of A. fischeri var. spinosus is reported. Chemical analysis showed that all isolates of A. flavus and A. parasiticus produced aflatoxin B₁, the isolates of A. versicolor and A. nidulans produced sterigmatocystin while the toxic isolate of A. ochraceus did not produce ochratoxins.Toxic fungi have been shown to occur in a variety of nuts (4), (5), (11), (12), (13), (15), (18), (20), (21). Aflatoxin contamination of pistachio nuts has been reported and has in the past led to the rejection of consignments of Iranian pistachio nuts (1). In Iran, pistachio nuts are produced mainly in the south eastern provinces (Kerman & Zahedan) and to a limited extent in the Northern part (Kazvin & Damghan). In 1975 it was estimated (7) that there were some 24 million pistachio trees in Iran, of which 60% were situated in Rafsanjan, Kerman (Table 1). Economic considerations as well as the potential health hazard posed by aflatoxin-contaminated nuts, prompted the University of Isfahan to initiate a study of various aspects of the mycotoxin problem in pistachio nuts.     

Parasitoid complex of the pistachio twig borer moth,Kermania pistaciella,in Iran

The parasitoid complex of the pistachio twig borer moth, Kermania pistaciella Amsel (Lepidoptera: Tineidae), a native pest of pistachio trees, was investigated at 27 pistachio plantation sites in Kerman province, the major pistachio growing area of Iran. The present study was conducted to document the naturally established parasitoid complex and to assess the need for improving the biological control of this species. In total, 22,390 moth cocoons were collected from 186 samples collected from commercial orchards during 2006–2008 and kept singly in controlled conditions to rear immature insects. An average of 2.8% of moth cocoons had been attacked by predators at time of sampling. Of the collected cocoons, on average 46.7% completed development and emerged as adult moths, no insects emerged from 8%, suggesting that the moth or wasp died before maturing, and parasitoids emerged from the remaining 42.5%. The overall percentage of host cocoons from which wasps emerged ranged from 25.6 to 59%. Fifteen hymenopterous parasitoid species were recovered from cocoons, of which three species were primary parasitoids, two were obligatory hyperparasitoids and the remaining 10 species were facultative hyperparasitoids. The primary parasitoid, Chelonus kermakiae (Tobias) (Hymenoptera: Braconidae), was the most abundant comprising almost 85% of the total emerging parasitoids. In addition, a further four species of larval parasitoid developed within the PTBM's larval tunnels in pistachio fruit cluster-stem tissue. Conservation of these parasitoids in the pistachio growing areas is recommended since a high level of parasitized moths’ cocoons was found at the majority of experimental sites.     

Parasitoids associated with the common pistachio psylla, Agonoscena pistaciae, in Iran

The parasitoids associated with the common pistachio psylla, Agonoscena pistaciae Burckhardt and Lauterer, were investigated at three pistachio plantations in Rafsanjan, Iran. Of the 6504 wasps emerging from mummified psyllids, 46% were the primary parasitoid Psyllaephagus pistaciae Ferrière, and the remaining 54% represented six species of hymenopterous hyperparasitoids, including Chartocerus kurdjumovi (Nikol’skaja), Marietta picta (André), Pachyneuron aphidis (Bouché), Pachyneuron muscarum (Linnaeus), Psyllaphycus diaphorinae (Hayat), and Syrphophagus aphidivorus (Mayr). Lysiphlebus fabarum Marshall, the parasitoid of Aphis gossypii Glover and Aphis craccivora Koch present on weeds, was found to be an alternative host for three major hyperparasitoids of A. pistaciae. The most abundant hyperparasitoid was S. aphidivorus, appearing during the growing season in all trial locations on psyllids and aphids in pistachio orchards. The weed-infesting aphids, along with their primary parasitoid, can act as a reservoir of A. pistaciae secondary parasitoids. Therefore, parasitized aphids allow populations of secondary parasitoids to increase and consequently to apply higher pressure on P. pistaciae. We detected that two primary parasitoid species, including P. pistaciae and L. fabarum, attacking different species of hosts interact indirectly through shared secondary parasitism. It is suggested that the community structure of A. pistaciae may be influenced by apparent competition, although more work is needed to provide firm evidence.     

Growth,physiological, biochemical and ionic responses of pistachio seedlings to mild and high salinity

Key message

Depending on salt concentrations, different mechanisms are involved in the tolerance of pistachio and an acclimation to salinity conditions occurs in the leaves that develop in the presence of salt.

Abstract

Pistachio (Pistacia vera L.) is a salt tolerant species that is considered an alternative crop for cultivation in salinzied orchard soils. In this work, 12-week-old pistachio seedlings cultivated in soil under greenhouse conditions were treated with five levels of salinity including control (0.63 dSm^?1), low (2 and 4 dSm^?1) and high (8 and 10 dSm^?1) salt concentrations for further 12 weeks. Plant growth parameters were not affected by mild salinity; a significant reduction was only observed from 8 dSm^?1. Considerable differences were observed between the young and mature leaves regarding osmotic and ionic stress effects of salt. Main compatible solutes were proline in mature leaves, proline and soluble sugars in young leaves, and soluble sugars and amino acids, other than proline, in roots. Concentration and content of Na in the leaves were not significantly increased at low levels of salinity and the K:Na and Ca:Na ratio of leaves were affected only by higher salt concentrations. Using the sequential extraction procedure for cell wall isolation, we observed that both absolute and relative amounts of Na in the cell wall fraction increased under low salinity, while decreased under higher levels of salt supply. Stable water relations, photochemistry and CO₂ assimilation rates particularly of young leaves, as well as ion homeostasis were mechanisms for maintenance of plants growth under mild salinity. Under severe saline conditions, the impaired ability of mature leaves for synthesis of assimilates, preferent allocation of carbohydrates to roots for maintenance of osmotic homeostasis and finally, reduction of protein synthesis caused growth inhibition in pistachio.     

Antioxidant activity and phenolic profile of pistachio (Pistacia vera L., variety Bronte) seeds and skins

Pistachio (Pistacia vera L.; Anacardiaceae) is native of aride zones of Central and West Asia and distributed throughout the Mediterranean basin. In Italy, a pistachio cultivar of high quality is typical of Bronte (Sicily), an area around the Etna volcano, where the lava land and climate allow the production of a nut with intense green colour and aromatic taste, very appreciated in international markets. Pistachio nuts are a rich source of phenolic compounds, and have recently been ranked among the first 50 food products highest in antioxidant potential. Pistachio nuts are often used after removing the skin, which thus represents a significant by-product of pistachio industrial processing. The present study was carried out to better characterize the phenolic composition and the antioxidant activity of Bronte pistachios, with the particular aim to evaluate the differences between pistachio seeds and skins. The total content of phenolic compounds in pistachios was shown to be significantly higher in skins than in seeds. By HPLC analysis, gallic acid, catechin, eriodictyol-7-O-glucoside, naringenin-7-O-neohesperidoside, quercetin-3-O-rutinoside and eriodictyol were found both in pistachio seeds than in skins; furthermore, genistein-7-O-glucoside, genistein, daidzein and apigenin appeared to be present only in pistachio seeds, while epicatechin, quercetin, naringenin, luteolin, kaempferol, cyanidin-3-O-galactoside and cyanidin-3-O-glucoside are contained only in pistachio skins. The antioxidant activity of pistachio seeds and skins were determined by means of four different assays (DPPH assay, Folin-Ciocalteau colorimetric method and TEAC assay, SOD-mimetic assay). As expected on the basis of the chemical analyses, pistachio skins have shown to possess a better activity with respect to seeds in all tests. The excellent antioxidant activity of pistachio skins can be explained by its higher content of antioxidant phenolic compounds. By HPLC-TLC analysis, gallic acid, catechin, cyanidin-3-O-galactoside, eriodictyol-7-O-glucoside and epicatechin appeared to be responsible for the antioxidant activity of pistachio skin, together with other unidentified compounds. In conclusion, our work has contributed to clarify some particular characteristics of Bronte pistachios and the specific antioxidant power of pistachio skins. Introduction of pistachios in daily diet may be of undoubted utility to protect human health and well-being against cancer, inflammatory diseases, cardiovascular pathologies and, more generally, pathological conditions related to free radical overproduction. On the other hand, pistachio skins could be successfully employed in food, cosmetic and pharmaceutical industry.     

Aflatoxin and sterigmatocystin contamination of pistachio nuts in orchards.

Aspergillus flavus and A. versicolor were both shown to be weak pathogens of developing pistachio fruits, producing aflatoxin and sterigmatocystin, respectively. Aflatoxin concentrations approached those reported in cereal and legume seeds. Fungus lesions on the first hulls were followed by invasion of seeds despite the sclerified shell. Infections and mycotoxins present before harvest would presumably lead to further build-up after harvest if drying was slow or storage was under high humidity.     

Effects of pyriproxyfen on some physiological aspects of the pistachio fruit hull borer,Arimania comaroffi Ragonot,pupae

The pistachio fruit hull borer, Arimania comaroffi (Lepidoptera: Pyralidae) is one of the minor pests of pistachio orchards. This pest passes the winter as pupae in silken cocoons in soil beside pistachio trees. In this study, effects of insect growth regulator pyriproxyfen were investigated on some physiological aspects of the pest by measuring glycogen, total sugar, lipid, protein, low-molecular-weight carbohydrates (trehalose and glucose) and polyols (sorbitol and myo-inositol) contents of the pupal body. Last larval instar was treated with 1?μl of the pesticide, and the effects on pupae were measured after one week. Glycogen content in treatment with 3.11?mg/g fresh body weight was significantly different from control with 8.51?mg/g fresh body weight, but no significant differences in protein and lipid contents (p?>?0.05) were observed. Glucose content in treated pupae with 1.50?mg/g fresh body weight was significantly different from control with 2.99?mg/g fresh body weight. Trehalose and sorbitol contents in treated pupae with 0.52 and 0.04?mg/g fresh body weight, respectively, were significantly lower than control with 2.07 and 1.5?mg/g fresh body weight, while there were no significant differences in glucose and myo-inositol contents between treated and control pupae.     

Molecular study of phytoplasmas associated with pistachio yellows in Iran

A large‐scale survey was conducted on pistachio plants exhibiting foliar symptoms including scorch, little leaf, yellows and reddish in pistachio growing areas in the Qom, Yazd and Qazvin provinces of Iran. Total DNA was extracted from symptomatic and symptomless pistachio and used in nested PCR assays with phytoplasma universal primers. Nested PCR products were obtained for symptomatic plant samples while the symptomless plants yielded no PCR products. Virtual restriction fragment length polymorphism, phylogenetic and DNA homology analyses of partial 16S ribosomal sequences of phytoplasma strains associated with symptomatic plants revealed the presence of phytoplasmas referable to two ribosomal groups; in particular, “Candidatus Phytoplasma solani” and “Ca. P. phoenicium” were identified. The presence of these phytoplasmas in pistachio is of great phytosanitary significance due to its commercial interest.     

Abundance and biological parameters of psyllophagous coccinellids in pistachio orchards

The abundance of coccinellids on pistachio trees was monitored at both a cultivated pistachio plantation and a wild pistachio growing area in Rafsanjan, Iran. Eleven ladybird species were identified from planted pistachio trees with Adalia bipunctata (Linnaeus) and Oenopia conglobata contaminata (Menetries) the most abundant ladybirds. At the wild pistachio plantation site, 17 coccinellid species were collected, with Brumus undulatus Weise the most abundant ladybird, followed by A. bipunctata and O. conglobata contaminata. Three species of Coccinellidae were evaluated for their potential for biological control of the common pistachio psylla (CPP), Agonoscena pistaciae Burckhardt and Lauterer. Coccinella undecimpunctata aegyptica (Reiche), Exochomus nigripennis (Erichson) and Hippodamia variegata (Goeze) developed successfully on A. pistaciae nymphs and reproduced successfully. Development and reproduction of these ladybirds were also examined on an alternative prey, the cotton aphid Aphis gossypii Glover, the most abundant aphid species on herbal weeds in pistachio orchards. The highest intrinsic rate of natural increase (r_m value) was observed in C. undecimpunctata aegyptica, 0.22 and 0.23 when it was fed on A. pistaciae and A. gossypii Glover, respectively. In comparison, the lowest r_m values (0.12 and 0.13) were found in E. nigripennis on the CPP and cotton aphid diets, respectively. Exochomus nigripennis consumed the largest number of psyllid nymphs during larval period, while the adults consumed the lowest number of psyllid nymphs daily. Although eight psyllophagous coccinellid species were collected in colonies of the CPP on pistachio trees, they did not regulate psyllid numbers below damaging levels. At present, conservation should assume a central role in biological control strategies for this pest.     

Comparison of pistachio hull essential oils from different Tunisian localities

Pistachio (Pistacia vera L.) fruit is well known for its oleaginous and edible seed. Less information is available about the hull constituted by the epicarp and the mesocarp. This part of the fruit contains an essential oil that can be valorized. Tunisia is one of the countries cultivating pistachio trees. This work presents essential oil composition of pistachio hulls (Mateur variety) from different geographical localities: Grombalia (North-East), Kairouan (Middle) and Sfax (Middle-East). Yields were more important in Sfax samples (0.53% on a dry weight basis). Alpha-terpinolene was the major compound for Grombalia fruits (35.7%), whereas Kairouan and Sfax samples where characterized by alpha-pinene (42.5 and 43.8% respectively). For all samples, monoterpene hydrocarbons predominated (more than 79.8% of the essential oil).     

Plant regeneration from encapsulated embryoids and an embryogenic mass of pistachio, Pistacia vera L.

Pieces of an embryogenic mass (EMS) induced in culture from immature fruits of pistachio, Pistacia vera L., were encapsulated into calcium alginate beads. Somatic embryos were also encapsulated individually into calcium alginate beads to produce synthetic seeds. The viability of the encapsulated EMS and somatic embryos was investigated immediately following encapsulation, and after storage for 60 days at 4°C. The encapsulated-stored EMS fragments recovered their original proliferative capacity after two months storage following two sub-cultures, but non-encapsulated-stored EMS failed to recover. The conversion frequency of synthetic seeds to seedling plants was 14% after storage for 60 days at 4°C, from which it may be concluded that encapsulation is a practical procedure for short-term storage of embryogenic pistachio tissue, and may be applicable to the preservation of desirable elite genotypes.Abbreviations BAP Benzylaminopurine - EMS(es) Embryogenic mass(es) - MS Murashige and Skoog medium (Sigma M-0404) - PGR(s) Plant growth regulator(s)     

Prediction of wild pistachio ecological niche using machine learning models

Observing vegetation dynamics and determining optimum conditions for tree species are important for the long-term habitat conservation. In this study we evaluate the environmental drivers that may explain the development and geographic distribution of Pistacia atlantica Desf. (wild pistachio) in Northeastern Iran. The study uses seven machine learning models to predict the habitats of P. atlantica: multivariate adaptive regression splines (MARS), flexible discriminant analysis (FDA), boosted regression tree (BRT), maximum entropy (MaxEnt), random forest (RF), support vector machine (SVM), generalized linear model (GLM), and their ensembles (ESMs). In total, 1477 P. atlantica sites were identified, described and mapped. The most relevant determinants of the species habitat were included as 28 bioclimatic, topographic, edaphic, and geologic components. While all the models returned high accuracies, the ESMs achieved the highest AUC, TSS, and Kappa values, suggesting a good predictive performance. The most important parameters explaining the species habitat were found to be the mean diurnal temperature range, annual precipitation and slope. These results support the higher performance of ESMs to predict the spatial distribution of P. atlantica. In turn, this model may support species conservation and decision-making at the regional and national levels.     

Toxic effects of pyriproxyfen,neemarin, acetamiprid and Ferula assafoetida essential oil on the common pistachio psylla,Agonoscena pistaciae

The common pistachio psylla, Agonoscena pistaciae, Burckhardt and Lauterer (Hemiptera: Psyllidae) is the key pest of pistachio orchards in Iran. Chemical control is the common method for the control of this pest. In this study, the effects of pyriproxyfen (an insect growth regulator), neemarin (a botanical insecticide), acetamiprid (a neonicotinoid) and Ferula assafoetida essential oil were investigated on the fifth instar nymphs of A. pistaciae. Probit analysis of concentration-mortality data was conducted to estimate the LC₅₀ values. The LC₅₀ values for neemarin, pyriproxyfen, acetamiprid and F. assafoetida essential oil were estimated to be 0.22, 0.52, 290 and 5.62 ppm, respectively. Our results showed that the fifth instar nymphs of A. pistaciae are very sensitive to neemarin and pyriproxyfen.     

Identification and quantification of the major endogenous cytokinins in pistachio seedlings

The major endogenous cytokinins, Z, ZR, DHZ, DHZR, iP and iPR in pistachio seedlings (Pistacia vera L. cv. Ohadi) were purified by HPLC and their identities confirmed using GC-MS. The aerial parts of two-year old pistachio seedlings including mature leaves, young leaves, lateral buds, debarked stems and bark were subjected to analysis. All of the above mentioned cytokinins were identified in the aerial parts except DHZ which was only present in mature leaves. Z-type cytokinins contributed almost 43% of the total cytokinins. ZR and DHZR were identified as the major ribosides and iP as the main base. The greatest concentration of ZR was detected in the bark, amounting to about 48%. DHZR and ZR constituted the major portion of the total cytokinins detected in both young and mature leaves while Z was detected as a minor cytokinin in leaves. The sharp increase of iP concentration during leaf maturation indicates that mature leaves are probably capable of de novo biosynthesis of cytokinins. The absence of DHZ (except in mature leaves) and the presence of considerable concentrations of DHZR in pistachio stems suggest that these tissues are able to metabolize DHZ to DHZR. The large amount of ZR in pistachio leaves suggests that root-derived ZR is transported into the leaves after loading into the xylem. The presence of high amounts of iP in pistachio lateral buds indicates that iP has been accumulated in these parts. The occurrence of a totally different cytokinin distribution pattern in buds, as compared with the other aerial parts, possibly results from their different metabolism.     

Micropropagation of the pistachio and its rootstocks by temporary immersion system

Although several studies have been reported on the micropropagation of the pistachio and its rootstocks, to date none of them had been efficient on the mass production of these plants in bioreactor systems. Thus, the micropropagation of juvenile pistachio shoot tips and nodal buds was investigated in a temporary immersion bioreactor system (RITA^®) and on a conventional semi-solid medium. Among the tested immersion conditions, immersion for 24 min every 16 h reduced vitrification and improved proliferation in the pistachio. Interactions were evident in immersion time and frequency in nodal segments. Nodal buds were better than shoot tips as the highest multiple shoot formation was recorded in MS medium containing 4 mg L^?1 BA and 0.1 mg L^?1 GA₃ in RITA^®. Although shoot tip necrosis (STN) was observed in shoots proliferated on semi-solid MS medium, such a symptom did not occur in shoots sprouted in the RITA^®. Additionally, these optimized conditions were applied to nodal buds of mature male pistachio ‘Atl?’ and Pistacia rootstocks (P. khinjuk Stocks and P. atlantica Desf.), and the micropropagation in the bioreactor system, in comparison to the semi-solid medium, was also improved. Furthermore, in vitro rooting of pistachio plantlets, despite the lower range (27.5 %), was also achieved in RITA^®. However, rooting was better on semi-solid medium for all tested species (ranged between 50 and 70 %). The results of this study showed that RITA^® could be used for the mass propagation of pistachio and its rootstocks, as well as for other woody plant species.     

Seasonal biology and abundance of Psyllaephagus pistaciae,a biocontrol agent of the common pistachio psylla Agonoscena pistaciae

The solitary endoparasitoid Psyllaephagus pistaciae Ferrière (Hymenoptera: Encyrtidae), is the most widely distributed biological control agent of the common pistachio psyllid, Agonoscena pistaciae Burckhardt and Lauterer (Hemiptera: Psylloidea), in Iran. The pupation and overwintering sites of diapausing parasitoids and the psyllid were studied for 2 years using emergence traps in pistachio orchards in Rafsanjan, Iran. The psyllid mummies containing the overwintering parasitoid adhered to pistachio leaves and were carried on these leaves away from the tree when they latter senesced. The present results verified that plant litter which included dried grasses and old pistachio leaves tended to support a greater population of adult winter-form psyllid and psyllid mummies during the winter through early spring than other options examined. Adult parasitoids appeared in the field in early April, about 30 days after the emergence of adult psyllids, but almost at the same time as the hatching of the first generation psyllid nymphs in early April. Rates of parasitism of CPP were generally low throughout most of the year, ranging from 1 to 5%, but rose in late autumn to about 11%. Results suggest that the density of P. pistaciae is not great enough to keep pace with the psyllid populations in these orchards. They explain why growers consider it necessary to apply pesticides for this pest. However, this parasitoid undoubtedly does play an important role in the natural control of A. pistaciae late in the growing season, particularly in non-sprayed orchards. Conservation of these natural enemies should be one of the objectives in the development of sustainable pest management programs.     

Introducing Bacillus licheniformis as the causal agent of pistachio dieback in Iran

During 2004 and 2006 growing seasons some pistachio trees in Kerman province of Iran showed dieback symptoms. Initial symptoms were observed at the beginning of the growing season and they developed during two weeks after green tip stage, as shoot tips turned black and dieback occurred. During the growing season, the symptoms developed and vessel destruction was observed. If these stems were not pruned during winter, dieback developed in the spring. During the growing season affected pistachio samples were collected and surface disinfected with 0.01% mercury chloride. Pieces of affected vessels were grown on nutrient agar (NA) and incubated at 25°C for three-to-four days. Bacterial colonies with Bacillus characteristics were isolated and 15 representative strains were selected for further characterisation. The pathogenicity of selected strains was verified on 2–3 year-old pistachio seedlings using injection of bacterial suspension (10⁷ cfu p/ml) and control plants inoculated with distilled water; vessel destruction developed after 20 days, and bacterial causal agent was isolated from seedlings. No symptoms were observed in control plants. The strains were Gram positive, motile, with central spores and caused a hypersensitivity reaction (HR) on tobacco and geranium; they were positive for anaerobic growth, nitrate reduction, utilisation of citrate, VP test, urease, catalase, growth at pH 5.7, 7% NaCl and 45°C, acid production from arabinose, xylose, glucose and mannitol, and anaerobic fermentation of glucose. They could hydrolyze starch, aesculin, Tween 80 and gelatin but indole production was negative. Based on the characteristics of the isolated strains, they were identified as Bacillus licheniformis. This is the first report of Bacillus licheniformis as a causal agent of pistachio dieback.