The Antioxidant Inhibition of Clove Effective Fraction on Lipid, Protein and Spectra Variation of LDL.

Oxidation of low density lipoprotein (LDL) has been considered as the critical factor which led to atherosclerosis (AS). Lipid and protein in LDL were oxidized to cause change of spectra during oxidation. Clove has been demonstrated to possess the strongest antioxidant capacity among 87 both medical and edible plants proclaimed by China. However, whether LDL oxidation is inhibited by clove? If so, whether it inhibits the oxidation of lipid and protein in LDL, and how does spectral characteristic of LDL change during oxidation when clove was added into LDL. Currently, these questions are still unclear. Therefore, the inhibition efficiency of the effective fraction from clove (EFC) on oxidation of LDL was studied by UV-Visible spectra and fluorescence spectra. The results indicated that EFC might effectively delay propagation of conjugated diene (CD) during LDL oxidation and postpone reaching maximum of its content. Likewise, it might inhibit cholesterol degradation, tryptophan (Trp) fluorescence quenching, lysine (Lys) residues from being modified, and lipofuscins from being generated in peroxidatic reaction among lipid and protein. Besides, EFC also might affect variation of UV-Visible spectra of LDL during oxidation. This study provides reference for future research and development of clove functional food inhibiting AS.

Hydrogen sulfide extends the postharvest life and enhances antioxidant activity of kiwifruit during storage.

BACKGROUND: Exogenous hydrogen sulfide (H2S) treatment can prolong the postharvest life of cut flowers and strawberries. Little work has been done to explore the effects of H2S on respiratory climacteric fruits such as kiwifruits during storage. Therefore the aim of the present study was to evaluate the effects of H2S treatment at concentrations of 15­1000 µmol L⁻¹ on the postharvest life of kiwifruit during 25 °C storage and the role of H2S in regulating the antioxidant defensive system of kiwifruit. RESULTS: Treatments with 45 and 90 µmol L⁻¹ H2S significantly inhibited the increase in soluble sugar content and the decrease in vitamin C (Vit C), chlorophyll content and firmness, inhibited ethylene production and both superoxide production rate (O(·2)⁻) and hydrogen peroxide content. Kiwifruits with 45 and 90 µmol L⁻¹ H2S exhibited significantly higher activities of superoxide dismutase, catalase and peroxidase. Treatment with 180 µmol L⁻¹ H2S promoted the ripening of kiwifruits. CONCLUSION: Treatments with 45 and 90 µmol L⁻¹ H2S could delay the maturation and senescence of kiwifruits and maintain higher titratable acid (TA) and Vit C during eating-ripe storage by inhibiting ethylene production, improving protective enzyme activities and decreasing the accumulation of reactive oxygen species to protect the cell membrane during storage.

Active pullulan-based coatings incorporated with Auricularia auricular extracts for preserving potato fresh-cuts.

In the present study, Auricularia auricular polysaccharides (AAP) and Auricularia auricular proteins (AAPR) obtained from the waste products of Auricularia auricular were incorporated into pullulan (PUL) to obtain active packaging films/coatings. Results showed that incorporating AAP/AAPR into PUL-based films decreased their transparency, but increased the compactness, thermal stability, antioxidant, and antimicrobial properties. Adding 2% PUL films with 10%:10% of AAP/AAPR exhibiting good mechanical properties were applied to fresh-cut potatoes to avoid spoilage during eight days of storage, with significantly decreased in browning index, weight loss, microbial growth prevention and the total soluble solids was maintained. These results substantiated that pullulan containing AAP/AAPR as an active film/coating with antioxidant and antimicrobial properties has significant potential for maintaining safety and quality of fresh-cut potatoes and extending their shelf life.

Structural and functional properties of Maillard-reacted casein phosphopeptides with different carbohydrates.

This study used glucose, fructose, maltose and dextran to explore the effects of different carbohydrates on the Maillard reaction of casein phosphopeptides (CPP). The color parameter results showed that heating time from 1 to 5 h led to brown color, which was consistent with the observed increased in browning intensity. Fourier transform infrared spectroscopy results verified that four carbohydrates reacted with CPP to produce Maillard conjugates. Fluorescence spectroscopy showed that the Maillard reaction changed the tertiary structure of CPP by decreasing the intrinsic fluorescence intensity and surface hydrophobicity compared with the CPP-carbohydrate mixture. At the same time, the Maillard reaction effectively improved the emulsifying properties, reducing power and DPPH radical scavenging activity of CPP. Furthermore, this study also found that glucose and fructose improved CPP more than maltose and dextran. Therefore, monosaccharides have good potential in modifying CPP via the Maillard reaction.

Hydrogen sulfide enhances kiwifruit resistance to soft rot by regulating jasmonic acid signaling pathway.

As the third active gas signal molecule in plants, hydrogen sulfide (H2S) plays important roles in physiological metabolisms and biological process of fruits and vegetables during postharvest storage. In the present study, the effects of H2S on enhancing resistance against soft rot caused by Botryosphaeria dothidea and the involvement of jasmonic acid (JA) signaling pathway in kiwifruit during the storage were investigated. The results showed that 20 µL L-1 H2S fumigation restrained the disease incidence of B. dothidea-inoculated kiwifruit during storage, and delayed the decrease of firmness and the increase of soluble solids (SSC) content. H2S treatment increased the transcription levels of genes related to JA biosynthesis (AcLOX3, AcAOS, AcAOC2, and AcOPR) and signaling pathway (AcCOI1, AcJAZ5, AcMYC2, and AcERF1), as well as the JA accumulation. Meanwhile, H2S promoted the expression of defense-related genes (AcPPO, AcSOD, AcGLU, AcCHI, AcAPX, and AcCAT). Correlation analysis revealed that JA content was positively correlated with the expression levels of JA biosynthesis and defense-related genes. Overall, the results indicated that H2S could promote the increase of endogenous JA content and expression of defense-related genes by regulating the transcription levels of JA pathway-related genes, which contributed to the inhibition on the soft rot occurrence of kiwifruit.

An Antifungal Role of Hydrogen Sulfide on Botryosphaeria Dothidea and Amino Acid Metabolism Involved in Disease Resistance Induced in Postharvest Kiwifruit.

Botryosphaeria dothidea is a major pathogen responsible for postharvest kiwifruit soft rot. This study aimed to determine the influence of hydrogen sulfide (H2S) on postharvest resistance to kiwifruit soft rot and the antifungal role of H2S against B. dothidea. The results indicated that H2S (20 µl L-1) restricted the lesion area following inoculation with B. dothidea. H2S enhanced the production of shikimic acid, tyrosine, tryptophan, and phenylalanine while also increasing the total phenols, flavonoids, and lignin. H2S upregulated the expression of AcDHQS, AcSDH, AcSK, AcPAL, AcCAD, and AcCHS. Additionally, sodium hydrosulfide (NaHS)-released H2S inhibited mycelial growth. NaHS concentrations of 20 and 40 mmol L-1 significantly decreased the mycelial weight and malondialdehyde content (MDA) content while increasing cell membrane conductivity and membrane leakage. The results indicate that H2S induces resistance in kiwifruit via a microbicidal role and amino acid metabolism involved in postharvest kiwifruit disease resistance.