Peanut Cotyledons Research Articles

Interrelationship between stilbene producing ability and Aspergillus colonization on selected peanut (Arachis hypogaea L.) genotypes

ABSTRACT Stilbenes are phytoalexins expressed by plants to avoid/resist certain biotic and abiotic stresses. This study was envisioned to determine the interrelationship between stilbenes producing ability of peanut genotypes and Aspergillus colonization level. Stilbenes were induced in peanut cotyledon in vitro by soaking in water, cutting them into thin slices, and subsequently challenging them with Aspergillus flavus. Fungal colonization was then measured in the cotyledon slices. The results showed major differences in fungal colonization levels between the control (seed without stilbene induction) and stilbenes-induced seeds. This finding was further validated using twenty peanut genotypes to ensure the relationship between stilbenes producing ability of the seed and fungal colonization level. The result showed that of the 20 genotypes tested, seeds of genotypes K1504, K1620 and K1632 showed minimal fungal colonization compared to control seed (without stilbenes induction), while genotypes DRT40, Kadiri-7, Narayani, DRT43 and Tirupati-3 showed no fungal colonization. The differences in stilbenes content and composition of cotyledon slices was determined by HPLC to assess genetic differences in their stilbenes producing ability. Comparative evaluation of these data showed that the genotypes that showed no fungal colonization expressed significantly higher amounts of stilbenes compared to genotypes which expressed relatively lower amounts of stilbenes. Overall, these data suggest that the genotypes expressing high amounts of stilbenes were able to mitigate fungal colonization while the genotypes expressing relatively lower amounts of stilbenes sustained fungal colonization, which indicates that this technique may be useful for screening breeding population to identify genotypes capable of avoiding Aspergillus colonization and aflatoxin contamination.

Using Short‐Wave Infrared Radiation to Improve Aqueous Enzymatic Extraction of Peanut Oil: Evaluation of Peanut Cotyledon Microstructure and Oil Quality

In this study, the effects of short‐wave infrared radiation (SIR) on enzyme‐assisted aqueous extraction process (EAEP) of peanut oil (PO) are investigated, including peanuts cotyledon cells mircrostructure and yield as well as quality of extracted PO. GC‐flash electronic nose (EN) combined with principal components analysis (PCA) is applied to select conditions for SIR process. The appropriate roasting condition based on the overall flavor is determined as 150 °C for 55 min. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are used to investigate the effects of SIR on cotyledon microstructure. The results demonstrated that SIR damaged the cell microstructure and oil body membrane, and the extraction of oil is facilitated. Accordingly, the oil yield increased significantly by 8.74% compared to that of the control (p < 0.05). Further analysis on the quality properties of PO revealed that the content of polyphenols of oil extracted from SIR roasted peanuts (2.79 ± 0.05 mg GAE kg−1) is 62.21% higher than that from the control. It is in consistent with the significantly enhanced oxidation stability of oil in the present study (p < 0.05). Furthermore, the variety and relative content of volatile compounds which contributed to a better overall flavor are greatly increased.Practical Applications: SIR as a mild and efficient roasting method could enhance the oil extraction yield in EAEP and improve the oxidation stability of the extracted oil. With the appropriate pre‐roasting of peanuts by SIR, the overall flavor of EAEP extracted peanut oil was improved. Its volatiles pattern was close to that of the commercial hot‐pressed PO. It was confirmed that SIR is a novel choice for roasting processing, as well as a potential and available pre‐roasting method of peanuts to improve the EAEP technology.In order to improve the enzyme‐assisted aqueous extraction process (EAEP) of peanut oil, short‐wave infrared radiation (SIR) to roast peanuts before the extraction process is used. SEM and TEM are employed to evaluate the roasting effects on cotyledon microstructure. Some chemical properties, the content of antioxidant compounds, and the flavor of extracted oil are assessed to show the effects on oil quality. The oil yield is also evaluated to explain the roasting effects together with the changes of the microstructure.

A comparative study on anthocyanin, saponin, and oil profiles of black and red seed coat peanut (Arachis hypogacea) grown in China

ABSTRACTThe objective of the current study was to investigate the chemical profiles among red and black peanut cultivars grown in China. Boiled peanut seeds lost colour values due to the loss of water-soluble pigments into the boiling water. The oil contents of eight out of ten cultivars are over 49 g/100g on dry weight basis. Peanut seed coat had much higher saponin compared with peanut cotyledon and the boiled peanut. Zhonghua No. 16 peanut had the highest saponin content in both seed coat (381.5 mg/g) and cotyledon (10.6 mg/g). Anthocyanin was comparatively higher in the black peanuts. It was also observed that the anthocyanin content had a close relationship with the colour of the peanuts. Cyanidin-3-O-sambubioside was one of the main anthocyanins present in black peanut cultivars. Seed coat was found to be the most nutritive part in the entire peanut kernel. It could also be considered as a potential source of nutraceuticals.

Peanut regeneration by somatic embryogenesis (SE), involving bulbil-like body (BLB), a new type of SE structure

Using cotyledons as explants a new method of peanut regeneration was established via somatic embryogenesis (SE), involving a kind of first-observed SE structure that was shaped like bulbil and therefore named bulbil-like body (BLB). On Murashige and Skoog (MS) media containing a higher concentration of 2,4-D (20.0 mg/L) and incubated in the dark, all the inoculated cotyledon explants formed BLBs with a high frequency of average 26 BLBs per cotyledon explant, and 100.00 % of the formed BLBs spontaneously developed into multiple shoots (3–5 shoots per BLB) without changing induction and incubation conditions. On average, about 103 shoots can be induced from an individual cotyledon explant. On MS media supplemented with 1.0 mg/L NAA all the separated shoots formed normal roots to develop into plantlets. The morphological and histological analyses of BLBs at different development stages revealed that BLB was a special kind of SE structure originated from cortex cells of peanut cotyledon explants, and each individual BLB was composed of multiple embryoids further developing into multiple shoots. To our knowledge, BLB is a novel type of SE structure in peanut different from the known SE structures because of its special shape, induction conditions, somatic embryogenic nature, and multiple-embryoid characteristics.

The influence of amino acid analogues on the development of isocitritase activity in peanut cotyledons

The influence of amino acid analogues on the development of isocitritase activity in peanut cotyledons

Some 2S albumin from peanut seeds exhibits inhibitory activity against Aspergillus flavus

A crude 2S albumin fraction was separated from peanut (Arachis hypogaea L.) cotyledons. Untreated 2S albumin had little inhibitory activity against trypsin, spore germination, or hyphal growth of Aspergillus flavus. However, following treatment of 2S albumin with SDS, increased inhibitory activity was demonstrated. We further purified 2S albumin using Sephadex G-100 and DEAE cellulose (DE-32) chromatography. HPLC analysis showed that the partially pure 2S albumin consisted of two polypeptides, whereas SDS-PAGE analyzes exhibited six polypeptides. One of the polypeptides, 2S-1, was found to contain the same molecular weight and enzymatic properties as the peanut protease inhibitor (PI); however, the N-terminal amino acid sequence of 2S-1 differed from that of PI. An NCBI database search revealed that the 2S-1 polypeptide is homologous to the pathogenesis-related proteins from soybean, cowpea, chickpea, and Lupinus luteus. We hypothesize that the 2S-1 polypeptide might represent a novel antifungal protein.

Proteomic Analysis Reveals an Aflatoxin-Triggered Immune Response in Cotyledons of Arachis hypogaea Infected with Aspergillus flavus

An immune response is triggered in host cells when host receptors recognize conserved molecular motifs, pathogen-associated molecular patterns (PAMPs), such as β-glucans, and chitin at the cell surface of a pathogen. Effector-triggered immunity occurs when pathogens deliver effectors into the host cell to suppress the first immune signaling. Using a differential proteomic approach, we identified an array of proteins responding to aflatoxins in cotyledons of peanut (Arachis hypogaea) infected with aflatoxin-producing (toxigenic) but not nonaflatoxin-producing (atoxigenic) strains of Aspergillus flavus. These proteins are involved in immune signaling and PAMP perception, DNA and RNA stabilization, induction of defense, innate immunity, hypersensitive response, biosynthesis of phytoalexins, cell wall responses, peptidoglycan assembly, penetration resistance, condensed tannin synthesis, detoxification, and metabolic regulation. Gene expression analysis confirmed the differential abundance of proteins in peanut cotyledons supplemented with aflatoxins, with or without infection with the atoxigenic strain. Similarly, peanut germination and A. flavus growth were altered in response to aflatoxin B1. These findings show an additional immunity initiated by aflatoxins. With the PAMP- and effector-triggered immune responses, this immunity constitutes the third immune response of the immune system in peanut cotyledon cells. The system is also a three-grade coevolution of plant-pathogen interaction.

Efficient production of Agrobacterium rhizogenes-transformed roots and composite plants in peanut (Arachis hypogaea L.)

Recalcitrance of most large-seeded legumes, such as peanut, to regeneration and genetic transformation has hampered studies on gene function and efforts for genetic improvement. Agrobacterium rhizogenes-mediated transformation provides a system for rapid and efficient transformation of plant tissues. In this study, embryonic axes along with cotyledons of peanut were injected with a suspension culture of A. rhizogenes using microliter syringes. The influence of several factors such as plant genotype, A. rhizogenes culture stage, co-culture period of A. rhizogenes, and acetosyringone concentration in the co-cultivation medium have been evaluated. It is found that A. rhizogenes-mediated transformation of peanut is genotype-independent. Up to 61% transformation was recorded when embryonic axes were co-cultivated with 5 × 107 A. rhizogenes cells from logarithmic phase for 2 days on co-culture medium containing 50 μmol l−1 acetosyringone. Composite plants with transgenic roots were harvested after 45 days of treatment. Furthermore, this method was applied to assess the insecticidal activity of a synthetic cry8Ea1 gene against Holotrichia parallela in transgenic roots of peanut.

Oleosin Is Bifunctional Enzyme That Has Both Monoacylglycerol Acyltransferase and Phospholipase Activities

In plants, fatty oils are generally stored in spherical intracellular organelles referred to as oleosomes that are covered by proteins such as oleosin. Seeds with high oil content have more oleosin than those with low oil content. However, the exact role of oleosin in oil accumulation is thus far unclear. Here, we report the isolation of a catalytically active 14 S multiprotein complex capable of acylating monoacylglycerol from the microsomal membranes of developing peanut cotyledons. Microsomal membranes from immature peanut seeds were solubilized using 8 m urea and 10 mm CHAPS. Using two-dimensional gel electrophoresis and mass spectrometry, we identified 27 proteins in the 14 S complex. The major proteins present in the 14 S complex are conarachin, the major allergen Ara h 1, and other seed storage proteins. We identified oleosin 3 as a part of the 14 S complex, which is capable of acylating monoacylglycerol. The recombinant OLE3 microsomes from Saccharomyces cerevisiae have been shown to have both a monoacylglycerol acyltransferase and a phospholipase A(2) activity. Overexpression of the oleosin 3 (OLE3) gene in S. cerevisiae resulted in an increased accumulation of diacylglycerols and triacylglycerols and decreased phospholipids. These findings provide a direct role for a structural protein (OLE3) in the biosynthesis and mobilization of plant oils.

Tracheobronchial foreign bodies in infants

Objective Tracheobronchial foreign body aspiration (FBA) is a common cause of respiratory distress between 1 and 3 years of age. Literature on airway foreign bodies in this age group is abundant; however no study has addressed this problem in infants exclusively. This study aimed to review the clinical presentation, management and outcome of infants with tracheobronchial foreign bodies at a referral tertiary care hospital over a decade. Methods 102 infants who underwent bronchoscopy for suspected FBA from 1997 to 2007 were retrospectively reviewed. Details of demographic data, clinical features, radiologic and bronchoscopic findings, postbronchoscopy events and eventual outcome were analysed. Results The mean age was 10.5 months. 8 (7.8%) were 0–6 months of age, the youngest being 2 months. Males outnumbered (72:30) females. 10 (9.8%) presented secondarily after treatment elsewhere, 6 of them were initially misdiagnosed. The onset-presentation interval ranged from 1 day to 3 months, 41 (40.2%) reporting within a day and 19 (18.6%) a week after onset. 20 (19.6%) had no history suggestive of FBA but harboured airway FBs at bronchoscopy. The clinical triad of cough, respiratory distress and stridor was highly predictive of FBA. 8 (7.84%) had no abnormal physical findings while 8 (10.81%) had grossly normal chest radiographs. All the patients underwent emergency/elective rigid bronchoscopy (Karl Storz system) under general anesthesia as in-patients. The physical findings did not always correlate with radiology or bronchoscopic location of the FB. A peanut cotyledon was the commonest FB retrieved across infancy; in 5 (4.9%) no FB was found/identifiable. 2 required postbronchoscopy mechanical ventilation and 1 a repeat bronchoscopy. There were 6 complications but no mortality in the series. The average hospital stay was 1.4 days. At a week's follow-up, all were asymptomatic and well. Conclusions The clinical presentation, diagnosis and management of FBA in 102 infants are presented and certain peculiar features are described. A high index of suspicion coupled with a combination of history, physical signs and radiology is more conclusive than any of them in isolation. Availability of expertise and endoscopic equipment ensures a favourable outcome without significant morbidity and mortality.

A Non-destructive Seed Sampling Method for PCR-based Analyses in Marker Assisted Selection and Transgene Screening

Extraction of quality DNA from peanut (Arachis hypogaea L.) generally requires extensive manipulation in order to remove numerous phenolic compounds and polysaccharides. To reduce the amount of problematic compounds present, routine purification of peanut DNA is normally performed on young leaf tissue which requires time and space for seed germination and growth of the peanut plant for at least two to four weeks. Here, we describe a simple, non-destructive method for extracting genomic DNA from a mature dry peanut seed that is of suitable quality for PCR-based molecular analysis. The method we developed requires only 0.02 g of peanut cotyledon tissue taken directly from the distal end of the mature dry seed and provides 30–46 µg of DNA suitable for use in restriction digests, PCR, SCAR and SSR analyses. This method is the first of its kind developed for DNA extraction from peanut seed. Since this method is non-destructive, seed can be subsequently germinated to produce healthy mature plants, making this technique a useful tool for the application of marker assisted selection in screening segregating populations of putative transgenic seed and in the advancement of breeding populations.

Cytosolic Triacylglycerol Biosynthetic Pathway in Oilseeds. Molecular Cloning and Expression of Peanut Cytosolic Diacylglycerol Acyltransferase

Triacylglycerols (TAGs) are the most important storage form of energy for eukaryotic cells. TAG biosynthetic activity was identified in the cytosolic fraction of developing peanut (Arachis hypogaea) cotyledons. This activity was NaF insensitive and acyl-coenzyme A (CoA) dependent. Acyl-CoA:diacylglycerol acyltransferase (DGAT) catalyzes the final step in TAG biosynthesis that acylates diacylglycerol to TAG. Soluble DGAT was identified from immature peanuts and purified by conventional column chromatographic procedures. The enzyme has a molecular mass of 41 +/- 1.0 kD. Based on the partial peptide sequence, a degenerate probe was used to obtain the full-length cDNA. The isolated gene shared less than 10% identity with the previously identified DGAT1 and 2 families, but has 13% identity with the bacterial bifunctional wax ester/DGAT. To differentiate the unrelated families, we designate the peanut gene as AhDGAT. Expression of peanut cDNA in Escherichia coli resulted in the formation of labeled TAG and wax ester from [14C]acetate. The recombinant E. coli showed high levels of DGAT activity but no wax ester synthase activity. TAGs were localized in transformed cells with Nile blue A and oil red O staining. The recombinant and native DGAT was specific for 1,2-diacylglycerol and did not utilize hexadecanol, glycerol-3-phosphate, monoacylglycerol, lysophosphatidic acid, and lysophosphatidylcholine. Oleoyl-CoA was the preferred acyl donor as compared to palmitoyl- and stearoyl-CoAs. These data suggest that the cytosol is one of the sites for TAG biosynthesis in oilseeds. The identified pathway may present opportunities of bioengineering oil-yielding plants for increased oil production.

Isolation of peanut genes encoding arachins and conglutins by expressed sequence tags

Seed storage proteins commonly comprise various groups of multiple isoforms encoded by different gene families. Arachin (11S globulin), conarachin (7S globulin) and conglutin (albumin) are the three major storage proteins in peanut ( Arachis hypogaea L.). In order to isolate peanut seed storage protein genes, we sequenced and analyzed more than 400 randomly selected clones from a cDNA library derived from mid-maturation stage cotyledons of peanut. Our analysis indicated that arachin isoform precursors were encoded by at least five genes, whereas conglutins were encoded by more than six genes. The full-length cDNAs that encode isoforms of five arachin and six conglutin precursors were obtained. Among these cDNA clones, the deduced polypeptide of Ara 1 has about 99% similarity to that of peanut allergen Ara h 3. In addition, the deduced amino acid sequences of three conglutins, AhCONG 1, AhCONG 2 and AhCONG 5, are identical to those of peanut allergens Ara h 2.02, Ara h 2 and Ara h 6, respectively. Our study identified four new members (Ara 2 to Ara 5) of arachin family and two new members (AhCONG 3 and AhCONG 6) of conglutin family in peanut.

Cloning and sequencing of the gene Ahy-β encoding a subunit of peanut conarachin

A cDNA expression library of mid-maturation cotyledons of peanut ( Arachis hypogaea L. Shanyou 523) was constructed to clone the genes of peanut seed storage proteins. Six clones of cDNA were obtained by immunoscreening with a polyclonal antibody against a 65 kD subunit of conarachin from peanut seeds. The six cDNA clones could be divided into two groups, Ahy- α and Ahy-β. Furthermore, a complete cDNA sequence of Ahy- β was determined by using rapid amplification of cDNA ends (RACE). Northern blot analysis showed that Ahy- β was expressed only in developing peanut embryos. Sequence analysis revealed that the Ahy- β gene with 2507 bp was composed of four exons with 703, 176, 81 and 882 bp and three introns with 71, 72 and 73 bp. The deduced amino acid encoded a protein with 614 residues. Several well characterized elements for promoter were observed in the 342 bp promoter region of Ahy-β and included two TATA-boxes, four CAAT-boxes, a vicilin-box, a G-box, a RY-1 element, two RY-2 elements and a P-element, while a poly-A signal and two additional stop codons existed in the 3′UTR.

Purification and properties of iminopeptidase from peanut seeds

Proline iminopeptidase (EC 3.4.13.8-9) is an aminopeptidase which can release specifically an amino-terminal proline residue from short peptides. We purified and characterized an iminopeptidase from cotyledons of peanuts by saline precipitation, ionic exchange in DEAE–Sepharose at pH 6.2 and 7.4, and preparative electrophoresis. The purified enzyme had a molecular weight of about 220 kDa by gel filtration. By sodium dodecyl sulfate–polyacrylamide gel electrophoresis, only a band of molecular weight of about 55 kDa was obtained, suggesting the oligomeric nature of iminopeptidase. An antiserum raised against the whole enzyme recognized a coincident single band on nitrocellulose-blots following denaturating gel electrophoresis of peanut cotyledons protein, supporting the hypothesis that this polypeptide is a subunit of enzyme. Optimal activity of the purified enzyme with l-proline– p-nitroanilide was observed at pH 8. The enzyme was inhibited by p-hydroxymercuribenzoate and N-ethylmaleimide, but was also inhibited by Phenylmethanesulphonyl fluoride and diisopropyl fluorphosphate. These results suggest that the enzyme cysteine and serine residues may participate in the enzyme activity. Twelve aminoacyl-β-naphtylamides were tested as substrates. Iminopeptidase hydrolyzed preferentially pro-β-naphtylamide but shows significant activity also against the derivatives of leu, met and ala. Short peptides with amino-terminal proline were hydrolyzed by the enzyme with variable intensity, but significant hydrolysis of salmine, a protein with the same N-terminus, was not detected.

Histochemical Localization of Amino Acids and Sugars in Peanut Cotyledons for Light Microscopy1

Abstract Light microscopy staining methods for amino acids and sugars were adapted for glutaraldehyde vapor-fixed, freeze dried, plastic embedded tissue of peanut cotyledons (Arachis hypogaea L.). These methods revealed the locale of amino acids and sugars, which are regarded as precursors of roasted peanut flavor compounds. Amino acids were localized in the protein bodies and cytoplasmic network by Coomassie Brilliant Blue G-250, Orange G, and diacetylbenzene. Sugars were localized in the protein bodies and cytoplasmic network by Alcian Blue - PAS procedure and an adaptation of the Okamoto method for sugars. Localization of the amino acids and sugars provide further evidence to the importance of the protein bodies in the cotyledon in the production of roasted peanut flavor.

Isolation of lysophosphatidic acid phosphatase from developing peanut cotyledons.

The soluble fraction of immature peanut (Arachis hypogaea) was capable of dephosphorylating [(3)H]lysophosphatidic acid (LPA) to generate monoacylglycerol (MAG). The enzyme responsible for the generation of MAG, LPA phosphatase, has been identified in plants and purified by successive chromatography separations on octyl-Sepharose, Blue Sepharose, Superdex-75, and heparin-agarose to apparent homogeneity from developing peanuts. This enzyme was purified 5,048-fold to a final specific activity of 858 nmol min(-1) mg(-1). The enzyme has a native molecular mass of approximately 39 kD determined by gel filtration and migrates as a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with a subunit molecular mass of 39 +/- 1.5 kD. The K(m) values for oleoyl-, stearoyl-, and palmitoyl-sn-glycerol-3-phosphate were determined to be 28.6, 39.3, and 47.9 microM, respectively. The LPA phosphatase was specific to LPA and did not utilize any other substrate such as glycerol-3-phosphate, phosphatidic acid, or p-nitrophenylphosphate. The enzyme activity was stimulated by the low concentrations of detergents such as Triton X-100 and octylglucoside. Cations had no effect on the enzyme activity. Fatty acids, sphingosine, and sphingomyelin at low concentrations stimulated the enzyme activity. The identification of LPA phosphatase in plants demonstrates the existence of MAG biosynthetic machinery in plants.

Transgenic peanut plants obtained by particle bombardment via somatic embryogenesis regeneration system.

After pre-culture and treatment of osmosis, cotyledons of immature peanut (Arachis hypogaea L.) zygotic embryos were transformed via particle bombardment with a plasmid containing a chimeric hph gene conferring resistance to hygromycin and a chimeric intron-gus gene. Selection for hygromycin resistant calluses and somatic embryos was initiated at 10th d post-bombardment on medium containing 10-25 mg/L hygromycin. Under continuous selection, hygromycin resistant plantlets were regenerated from somatic embryos and were recovered from nearly 1.6% of the bombarded cotyledons. The presence and integration of foreign DNA in regenerated hygromycin resistant plants was confirmed by PCR (polymerase chain reaction) for the intron-gus gene and by Southern hybridization of the hph gene. GUS enzyme activity was detected in leaflets from transgenic plants but not from control, non-transformed plants. The production of transgenic plants are mainly based on a newly improved somatic embryogenesis regeneration system developed by us.

Identification, Purification, and Characterization of Monoacylglycerol Acyltransferase from Developing Peanut Cotyledons

Biosynthesis of diacylglycerols in plants occurs mainly through the acylation of lysophosphatidic acid in the microsomal membranes. Here we describe the first identification of diacylglycerol biosynthetic activity in the soluble fraction of developing oilseeds. This activity was NaF-insensitive and acyl-CoA-dependent. Diacylglycerol formation was catalyzed by monoacylglycerol (MAG) acyltransferase (EC ) that transferred an acyl moiety from acyl-CoA to MAG. The enzyme was purified by successive chromatographic separations on octyl-Sepharose, blue-Sepharose, Superdex-75, and palmitoyl-CoA-agarose to apparent homogeneity from developing peanut (Arachis hypogaea) cotyledons. The enzyme was purified to 6,608-fold with the final specific activity of 15.86 nmol min(-1) mg(-1). The purified enzyme was electrophoretically homogeneous, and its molecular mass was 43,000 daltons. The purified MAG acyltransferase was specific for MAG and did not utilize any other acyl acceptor such as glycerol, glycerol-3-phosphate, lysophosphatidic acid, and lysophosphatidylcholine. The K(m) values for 1-palmitoylglycerol and 1-oleoylglycerol were 16.39 and 5.65 micrometer, respectively. The K(m) values for 2-monoacylglycerols were 2- to 4-fold higher than that of the corresponding 1-monoacylglycerol. The apparent K(m) values for palmitoyl-, stearoyl-, and oleoyl-CoAs were 17.54, 25.66, and 9.35 micrometer, respectively. Fatty acids, phospholipids, and sphingosine at low concentrations stimulated the enzyme activity. The identification of MAG acyltransferase in oilseeds suggests the presence of a regulatory link between signal transduction and synthesis of complex lipids in plants.

NMR stray-field analysis of oil drop size distribtuion in peanut cotyledons.

The technique of stray-field NMR has been applied to the study of an oil-bearing seed. It is found to provide additional information about the smallest size of oil drops within the cotyledon not easily measurable by other methods. A peanut was chosen as a convenient seed to investigate so as to allow comparison with previously published NMR pulsed field gradient data. We find a broad distribution of oil drop sizes ranging from a lower limit of order 0.26 microm up to a maximum of approximately 1.3 microm.