Pistachio Kernels Research Articles

Gibberellic acid and benzyladenine reduce hull-splitting and aflatoxin levels in pistachio kernels

SummaryThe effects of gibberellic acid and a cytokinin on hull-splitting and aflatoxin levels in pistachio (Pistacia vera L. cv. ‘Owhadi’) were studied in a commercial orchard over 2 years. Gibberellin (GA3) at 25, 50 and 100 mg l–1 and benzyladenine (BA) at 50 and 100 mg l–1 reduced hull-splitting and infection by Aspergillus spp. with a strong correlation between splitting and infection (R2 = 0.88). GA3 and BA at high concentrations reduced hull-splitting to 0.6% and 0.3%, respectively. Kernels from trees treated with GA3 and BA at 50 or 100 mg l–1 had no aflatoxins compared with 4.7 ng g–1 in non-treated trees. BA also increased crude fat and chlorophyll levels in the kernels of pistachio fruit. Applications of GA3 or BA are recommended for commercial pistachio production.

Identification of Pistachio (Pistacia vera L.) Nuts with Microsatellite Markers

A genomic DNA library enriched for dinucleotide (CT)n and (CA)n and trinucleotide (CTT)n microsatellite motifs has been developed from `Kerman' pistachio (Pistacia vera L.). The enrichment method based on magnetic or biotin capture of repetitive sequences from restricted genomic DNA revealed an abundance of simple sequence repeats (SSRs) in the pistachio genome which were used for marker development. After an enrichment protocol, about 64% of the clones contained (CT)n repeats while 59% contained (CA)n for CT and CA enriched libraries, respectively. In the (CT)n enriched library, compound sequences were 45% while for (CA)n it was 13.5%. In both dinucleotide enriched libraries, about 80% of the clones having microsatellites have a repeat length in the range of 10 to 30 units. A library enriched for trinucleotide (CTT)n contained <19% of the clones with (CTT)n repeats. Of the clones that contained microsatellites, 62% had sufficient flanking sequence for primer design. An initial set of 25 pairs of primers was designed, out of which 14 pairs amplified cleanly and produced an easily interpretable PCR product in the commercially important American, Iranian, Turkish, and Syrian pistachio cultivars. The efficient DNA extraction method developed for pistachio kernels and shells (roasted and nonroasted) yielded DNA of sufficient quality to use PCR to create DNA fingerprints. In total, 46 alleles were identified by 14 primer pairs and a dendrogram was constructed on the basis of that information. The SSR markers distinguished most of the tested cultivars from their unique DNA fingerprint. An UPGMA cluster analysis placed most of the Iranian samples in one group while the Syrian samples were the most diverse and did not constitute a single distinct group. The maximum number of cultivar specific markers were found in `Kerman'(4), the current industry standard in the United States, and the Syrian cultivar Jalab (5). The technique of using extracted DNA from pistachio kernal or shell coupled with the appropriate marker system developed here, can be used for analyses and measurement of trueness to type.

Determination of Aflatoxin Bi in Pistachio Kernels and Shells

A method was developed for accurate measurement of aflatoxin B1 in the edible portion of pistachio nuts. Twenty-nine samples of kernels with and without their shells were slurried with a Mega Ultra Turrax. A subsample of the homogenate was extracted with water-methanol, defatted with petroleum ether, purified with a silica solid-phase extraction column, and redissolved in methanol. After separation on an octadecyl column and postcolumn reaction with on-line electrochemically generated bromine, the aflatoxin B1 derivative was detected fluorometrically. The shells contained less than 1% of the aflatoxin B1 found in the edible kernel, and they accounted for 41.7-46.8% of the weight of the whole pistachio. These observations indicate it is possible to analyze an entire sample, up to 25 kg, as a whole and still be able to judge whether it meets the legal tolerance limit of 5 micrograms aflatoxin B1/kg edible part, as set by the Dutch Food Act.

Aflatoxin variability in pistachios.

Pistachio fruit components, including hulls (mesocarps and epicarps), seed coats (testas), and kernels (seeds), all contribute to variable aflatoxin content in pistachios. Fresh pistachio kernels were individually inoculated with Aspergillus flavus and incubated 7 or 10 days. Hulled, shelled kernels were either left intact or wounded prior to inoculation. Wounded kernels, with or without the seed coat, were readily colonized by A. flavus and after 10 days of incubation contained 37 times more aflatoxin than similarly treated unwounded kernels. The aflatoxin levels in the individual wounded pistachios were highly variable. Neither fungal colonization nor aflatoxin was detected in intact kernels without seed coats. Intact kernels with seed coats had limited fungal colonization and low aflatoxin concentrations compared with their wounded counterparts. Despite substantial fungal colonization of wounded hulls, aflatoxin was not detected in hulls. Aflatoxin levels were significantly lower in wounded kernels with hulls than in kernels of hulled pistachios. Both the seed coat and a water-soluble extract of hulls suppressed aflatoxin production by A. flavus.

Aflatoxins and fluorescence in Brazil nuts and pistachio nuts

Brazil nut and pistachio nut samples from lots known to be contaminated with aflatoxins were visually inspected in detail. Kernels were split lengthwise in halves, and internally highly discolored kernels were analyzed individually. Highly contaminated Brazil nut kernels showed yellow fluorescence if illuminated with light at 360 nm. However, not all fluorescent kernels were contaminated with aflatoxins, and brown spotted kernels also contained these toxins. While contaminated Brazil nut kernels showed different appearance, only brown or brown spotted pistachio kernels were highly contaminated with aflatoxins

Effects of gamma irradiation on the lipids, carbohydrates and proteins of Iranian pistachio kernels

Effects of gamma irradiation on the lipids, carbohydrates and proteins of Iranian pistachio kernels

Effect of salting and roasting on the carbohydrates and proteins of Iranian pistachio kernels

SummaryThe free sugars which make up 2.7% of Iranian pistachio cv Badami were identified as fructose, glucose, sucrose, maltose, isomaltose, cellobiose, raffinose and stachyose. Both protein and free amino acids contained the same seventeen amino acids but lacked tryptophan, asparagine and glutamine. After salting and roasting, total available carbohydrates, total starches and dextrins, and total free sugars all decreased compared to controls, as did a number of individual sugars, especially the reducing sugars. While free amino acids had severely decreased, total protein amino acids and individual protein amino acid were not affected at all. The decreases in reducing sugars and in free amino acids may be due in part to their taking part in Maillard reactions.

Effect of salting and roasting on the lipids of Iranian pistachio kernels

SummaryThe simple lipids which make up 95% total lipids of Iranian pistachio kernels were identified as sterols and their esters; mono‐, di‐ and tri‐glycerides; and free fatty acids while the complex lipids were sterolglycosides; mono‐ and di‐galactosyldiglycerides; cardiolipin, phosphatidyl‐choline, ‐ethanolamine, ‐serine and ‐inositol; sphingolipid and phosphatidic acid. After salting and roasting, there was an increase in free fatty acids and in phosphatidic acid. Total fatty acids made up of C14:0, C16:0, C18:1, C18:2, C18:3 and C20:O were not significantly altered after roasting, nor was the iodine value, nor the malonaldehyde content. However, the peroxide value was increased.

The Structure of the glycerides of pistachio kernel oil

AbstractPistachio kernel oil has been analyzed by separating the triglycerides according to their degree of unsaturation by means of thin layer chromatography on silica gel plates impregnated with silver nitrate. The total fatty acids and the fatty acid on position 2 of each individual triglyceride were determined. The distribution of oleic acid on the different positions of triglycerides varies according to the unsaturation of these triglycerides. Oleic acid in the case of the less unsaturated triglycerides locates in the 2‐position, and, as the degree of unsaturation increases due to linolenic or linoleic acids, it tends to be on external positions. Linoleic and linolenic acids usually are esterified in the middle position.

COMPOSITION OF PISTACHIO KERNELS OF VARIOUS IRANIAN ORIGINS

ABSTRACTIn order to establish the composition of pistachio kernels of various Iranian cultivars, nine samples from different origins were studied. The amounts of the constituents in 100g kernel were within the following ranges: moisture 2.5–4.1%; ash 2.2–2.5%; oil 55.2–60.5%; fiber 1.7–2.0%; protein 15.0–21.2%; carbohydrate 14.9–17.7%; Na 4.0–7.0 mg; K 1048–1142 mg; Ca 120–150 mg; P 494.0–514.5 mg; Fe 5.8–11.4 mg; Cu 1.0–1.4 mg; Mg 157.5–165.0 mg. The differences in values of different samples were not appreciable.

Fatty acid, carbohydrate and amino acid composition of pistachio (pistacia vera) Kernels

The fatty acid, carbohydrate and amino acid composition of dried pistachio kernels was determined. On a dry weight basis they contained about 55% oil. The unsaturated fatty acids oleic and linoleic constituted about 80% of this oil. Carbohydrate analysis of a hydrolysed sample showed the predominant sugar to be glucose followed by galactose and mannose with traces of fucose, arabinose and xylose. The total amino acid content was about 25% by weight. Nine essential amino acids were present with only cystine in a limiting amount and with a high level of lysine.

Characteristics of pistachio kernel oils from Iranian cultivars

AbstractTen pistachio samples from various Iranian cultivars were examined for some botanical features of their nuts and oil characteristics of their kernels. The wt of 100 nuts varied from 78.5 to 136.9 g. The nuts contained 44.1–58.9% kernel. Moisture of the kernels was low, 2.5–4.1%, and the kernels contained 55.2–60.5% oil. Unsaponifiable matter (0.72–0.96%), saponification value (189.0–193.6), refractive index (1.4635–1.4643), and iodine value (98.1–100.5) showed little differences in various samples. Fatty acids detectable by gas chromatographic analysis were: traces of myristic; 9.2–13.4%, palmitic; 0.5–1.1%, stearic; traces of arachidic; 0.5–1.0%; palmitoleic; 56.1–64.0%, oleic; 22.6–31.0%, linoleic; and 0.1–0.4%, linolenic. There were no significant differences due to origin and/or cultivar of the samples.