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Poupard P Sanoner P Baron A Renard CM Guyot S 《Journal of mass spectrometry : JMS》2011,46(11):1186-1197
Procyanidins (i.e. condensed tannins) are polyphenols commonly found in fruits. During juice and cider making, apple polyphenol oxidase catalyzes the oxidation of caffeoylquinic acid (CQA) into its corresponding o-quinone which further reacts with procyanidins and other polyphenols, leading to the formation of numerous oxidation products. However, the structure and the reaction pathways of these neoformed phenolic compounds are still largely unknown. Experiments were carried out on a model system to gain insights into the chemical processes occurring during the initial steps of fruit processing. Procyanidin B2 was oxidized by caffeoylquinic acid o-quinone (CQAoq) in an apple juice model solution. The reaction products were monitored using high performance liquid chromatography (HPLC) coupled to ultraviolet (UV)-visible and electrospray tandem mass spectrometry (ESI-MS/MS) in the negative mode. Oxidative conversion of procyanidin B2 ([M-H](-) at m/z 577) into procyanidin A2 at m/z 575 was unambiguously confirmed. In addition, several classes of products were characterized by their deprotonated molecules ([M-H](-)) and their MS/MS fragmentation patterns: hetero-dimers (m/z 929) and homo-dimers (m/z 1153 and 705) resulting from dimerization involving procyanidin and CQA molecules; intramolecular addition products at m/z 575, 573, 927, 1151 and 703. Interestingly, no extensive polymerization was observed. Analysis of a cider apple juice enabled comparison with the results obtained on a biosynthetic model solution. However, procyanidin A2 did not accumulate but seemed to be an intermediate in the formation of an end-product at m/z 573 for which two structural hypotheses are given. These structural modifications of native polyphenols as a consequence of oxidation probably have an impact on the organoleptic and nutritional properties of apple juices and other apple-derived foods. 相似文献
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Mohammed Kara Amine Assouguem Omkulthom Mohamed Al kamaly Safa Benmessaoud Hamada Imtara Hamza Mechchate Christophe Hano Abdou Rachid Zerhouni Jamila Bahhou 《Molecules (Basel, Switzerland)》2021,26(18)
Apple vinegar is a natural product widely used in food and traditional medicine as it contains many bioactive compounds. The apple variety and production methods are two factors that play a major role in determining the quality of vinegar. Therefore, this study aims to determine the quality of apple vinegar samples from different varieties (Red Delicious, Gala, Golden Delicious, and Starking Delicious) prepared by three methods using small apple pieces, apple juice, and crushed apple, through determining the physicochemical properties and antibacterial activity of these samples. The antibacterial activity was studied against five pathogenic bacteria: Staphylococcus aureus, Klebsiella pneumonia, Escherichia coli (ATB: 57), Escherichia coli (ATB: 97), and Pseudomonas aeruginosa, using two methods, disk diffusion and microdilution, for determining the minimum inhibitory concentrations and the minimum bactericidal concentrations. The results of this study showed that the lowest pH value was 3.6 for Stark Delicious, obtained by liquid fermentation, and the highest acetic acid values were 4.7 and 4% for the vinegar of Red Delicious and Golden Delicious, prepared by solid fermentation, respectively. The results of the antibacterial activity showed considerable activity of apple vinegar on the tested strains. Generally, the Staphylococcus aureus strain appears less sensitive and Pseudomonas aeruginosa seems to be very sensitive against all samples, while the other strains have distinct sensitivities depending on the variety studied and the method used. A higher antibacterial activity was found in vinegar obtained by the apple pieces method and the Red Delicious variety, with a low MIC and MBC recorded, at 1.95 and 3.90 µL/mL, respectively. This study has shown that the choice of both apple variety and production method is therefore an essential step in determining and aiming for the desired quality of apple vinegar. 相似文献
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采用不同化学屏蔽方法和傅里叶变换红外光谱(FTIR)分析,对灭活酿酒酵母菌吸附展青霉素的机理进行了研究。化学屏蔽法与酿酒酵母菌对展青霉素的吸附结果表明:酿酒酵母菌经过丙酮和NaOH处理后对展青霉素的吸附明显增加,而经过氨基甲基化和羧基酯化处理的酵母菌对展青霉素的吸附能力显著下降,细胞壁上的羧基和氨基参与了吸附过程。红外光谱分析结果表明,吸附前后红外光谱图发生了一些变化,与变化有关的主要是存在于细胞壁蛋白质和糖类上的氨基、羧基和羟基。 相似文献
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María Jesús Lerma‐García Maria Nicoletti Ernesto Francisco Sim‐Alfonso Pier Giorgio Righetti Elisa Fasoli 《Electrophoresis》2019,40(2):266-271
Combinatorial peptide ligand libraries coupled to MS was applied to extensively map the proteome of apple fruit, and to detect its presence in commercial apple juice and cider to evaluate their authenticity and genuineness. Using the Uniprot_Malus database, 96 proteins were detected in apples, among which 30 proteins were specifically captured via combinatorial peptide ligand libraries. Next, three proteins, previously recognized in fruits, were found in apple juice, which were involved in cellular metabolism of fruit maturation and in allergenic reactions. On the other hand, only one Malus allergen was identified in cider beads eluate, demonstrating that the industrial processes did not prevent any negative effects in sensitive subjects. Thus, the present study not only increases the knowledge of the apple proteome but also offers a reliable analytical method to assess quality and genuineness of commercial products, which could be also used to inform consumers about the presence of allergens. 相似文献
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Judy Gopal Vimala Anthonydhason Manikandan Muthu Enkhtaivan Gansukh Somang Jung Sechul Chul 《Natural product research》2019,33(6):906-910
These are the days when one would go online first seeking home remedies before seeing a doctor. Apple cider vinegar (ACV) is one such popular yet scientifically under-validated remedy. Our results prove the unequivocal antimicrobial activity of ACV to be true at full strength concentrations. However, the activity cannot be generalised because although strong antibacterial activity was observed at 25% concentrations, in terms of antifungal activity, yeasts, especially Candida were found to be less susceptible. The antimicrobial/antioxidant properties are ascertained to the total phenolic contents of ACV, as confirmed by our characterisation of the bioactive compounds and antioxidant activity. When checking for its cytotoxicity, ACV exhibited toxicity even at concentrations as low as 0.7%. These results indicate that there is no question of generalising the idea of ACV usage, instead more in vitro and in vivo validations are necessary in order to precisely weigh the pros and cons of ACV. 相似文献
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