Effect of High Temperature Storage Condition on Quality Deterioration of Peanut Oil and Protein

Peanut is an important oilseed crop, susceptible to quality deterioration under harsh storage conditions because of its high oil content. In order to explore the effects of different storage temperatures on peanut quality under normal humidity conditions, in-shell peanuts were stored at 15, 25 or 35 ℃ for up to 30 weeks. Indicators of lipid oxidation: acid value (AV), peroxide value (PV), and malondialdehyde (MDA) content; indicators of protein oxidation: carbonyl, sulfhydryl, disulfide bond contents; and the activities of oxidation-related enzymes: lipase (LPS), lipoxygenase (LOX) and peroxidase (POD) were tested. The results showed that the AV increased from (0.48 ± 0.01) to (1.78 ± 0.02) mg/g and the carbonyl content from (3.19 ± 0.24) to (118.61 ± 6.41) μmol/g over the storage period at 25 ℃. Meanwhile, at the end of storage, the highest lipase and lipoxygenase activities were observed in the sample stored at 35 ℃, which were (59.00 ± 1.70) and (1 287.17 ± 98.45) U/g, respectively; the AV increased from (0.48 ± 0.01) to (3.15 ± 0.10) mg/g, the MDA content from 23.03 to 1 039.63 nmol/g, and the carbonyl content from (3.19 ± 0.24) to (124.86 ± 3.07) μmol/g. At 15 ℃, the highest lipase and lipoxygenase activities were only (41.60 ± 1.23) and (1 036.14 ± 34.49) U/g, respectively and the peroxide and carbonyl contents increased by 18.4 and 17.1 times after 30 days of storage, respectively, reaching much lower levels than those at the other temperatures. In conclusion, storage at normal humidity and at 15 ℃ can effectively suppress the oxidase activity at a low level at all time points, resulting in a low degree of oxidation of peanut oil and protein, while high ambient temperature increases the oxidase activity, and the higher the temperature, the higher the enzyme activity, and the higher the contents of primary and secondary oxidation products in oil, indicating a higher degree of peroxidation. Moreover, protein oxidation also occurs due to the oxidation of amino acid side chains and protein structural damage, ultimately leading to a decline in peanut quality

Photoacoustic Identification of Laser-induced Microbubbles as Light Scattering Centers for Optical Limiting in Liquid Suspension of Graphene Nanosheets

Liquid suspensions of carbon nanotubes, graphene and transition metal dichalcogenides have exhibited excellent performance in optical limiting. However, the underlying mechanism has remained elusive and is generally ascribed to their superior nonlinear optical properties such as nonlinear absorption or nonlinear scattering. Using graphene as an example, we show that photo-thermal microbubbles are responsible for the optical limiting as strong light scattering centers: graphene sheets absorb incident light and become heated up above the boiling point of water, resulting in vapor and microbubble generation. This conclusion is based on direct observation of bubbles above the laser beam as well as a strong correlation between laser-induced ultrasound and optical limiting. In-situ Raman scattering of graphene further confirms that the temperature of graphene under laser pulses rises above the boiling point of water but still remains too low to vaporize graphene and create graphene plasma bubbles. Photo-thermal bubble scattering is not a nonlinear optical process and requires very low laser intensity. This understanding helps us to design more efficient optical limiting materials and understand the intrinsic nonlinear optical properties of nanomaterials

A genetic variation map for chicken with 2.8 million single-nucleotide polymorphisms

We describe a genetic variation map for the chicken genome containing 2.8 million single-nucleotide polymorphisms ( SNPs). This map is based on a comparison of the sequences of three domestic chicken breeds ( a broiler, a layer and a Chinese silkie) with that of their wild ancestor, red jungle fowl. Subsequent experiments indicate that at least 90% of the variant sites are true SNPs, and at least 70% are common SNPs that segregate in many domestic breeds. Mean nucleotide diversity is about five SNPs per kilobase for almost every possible comparison between red jungle fowl and domestic lines, between two different domestic lines, and within domestic lines - in contrast to the notion that domestic animals are highly inbred relative to their wild ancestors. In fact, most of the SNPs originated before domestication, and there is little evidence of selective sweeps for adaptive alleles on length scales greater than 100 kilobases

The Genomes of Oryza sativa: A History of Duplications

We report improved whole-genome shotgun sequences for the genomes of indica and japonica rice, both with multimegabase contiguity, or almost 1,000-fold improvement over the drafts of 2002. Tested against a nonredundant collection of 19,079 full-length cDNAs, 97.7% of the genes are aligned, without fragmentation, to the mapped super-scaffolds of one or the other genome. We introduce a gene identification procedure for plants that does not rely on similarity to known genes to remove erroneous predictions resulting from transposable elements. Using the available EST data to adjust for residual errors in the predictions, the estimated gene count is at least 38,000–40,000. Only 2%–3% of the genes are unique to any one subspecies, comparable to the amount of sequence that might still be missing. Despite this lack of variation in gene content, there is enormous variation in the intergenic regions. At least a quarter of the two sequences could not be aligned, and where they could be aligned, single nucleotide polymorphism (SNP) rates varied from as little as 3.0 SNP/kb in the coding regions to 27.6 SNP/kb in the transposable elements. A more inclusive new approach for analyzing duplication history is introduced here. It reveals an ancient whole-genome duplication, a recent segmental duplication on Chromosomes 11 and 12, and massive ongoing individual gene duplications. We find 18 distinct pairs of duplicated segments that cover 65.7% of the genome; 17 of these pairs date back to a common time before the divergence of the grasses. More important, ongoing individual gene duplications provide a never-ending source of raw material for gene genesis and are major contributors to the differences between members of the grass family

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead