Impact of shelf life on content of primary and secondary metabolites in apple (Malus domestica Borkh.)

In this study, we evaluated the changes in apple fruit quality during shelf life. After a month of cold storage, apples of cultivars "Jonagold" and "Golden Delicious" were exposed to ambient temperatures for 21 d, with subsequent sampling every 3 or 4 d. Fruit firmness, changes in amounts of sugars, malic acid, and phenolics were observed during shelf life. Chemical analyses were done with HPLC-PDA system. An interchange between various sugars was noticed, but in general, the sum of sugars remained at the same level. The content of malic acid remained stable or dropped, resulting in sweeter fruit. Levels of phenolics were more constant in the pulp of both cultivars analyzed, while in the peel, the changes were more pronounced. In the pulp, a peak in the content of hydroxycinnamic acids and flavanols was noticed on the 2nd or 3rd sampling and afterwards, the amounts remained constant. In the peel an initial decrease of all analyzed phenolic groups was observed in both cultivars, however it was more pronounced in "Jonagold." It can be concluded that changes in primary and secondary metabolites are not the main reason for the lower quality of fruit exposed to ambient temperatures. On the other hand, fruit firmness might be the limiting factor for shelf life duration.     

Characterization and Implications of Enterobacter cloacae Strains, Isolated from Italian Table Olives "Bella Di Cerignola"

ABSTRACT:  Enterobacter cloacae  can be recovered in the spontaneous fermentations of Italian table olives. In this study, the effects of salt (20 to 100 g/L), temperature (10 to 37 °C), pH (4 to 5 and 8 to 10),  p -coumaric and vanillic acids (0.5 to 2 g/L), and the acidification of the medium through lactic, citric, and ascorbic acids were investigated on 15 strains of  E. cloacae , isolated from Italian table olives "Bella di Cerignola." Finally, a confirmatory experiment in synthetic brine was run. The strains were inhibited only by an NaCl amount of 70 to 80 g/L and by  p -coumaric acid; on the other hand, they showed the ability to grow also at low temperatures (10 to 15 °C). The confirmatory experiment highlighted their ability to survive both at 15 °C and at pH 5.  Enterobacter cloacae  could be a real problem for the fermentation of table olives in southern Italy; some hurdles could be used (salt or brine acidification), but some environmental conditions (for example, the temperature) should be controlled carefully to maintain olive safety at acceptable levels.     

Metabolite profiling of doenjang,fermented soybean paste,during fermentation

BACKGROUND: A fermented soybean paste known as doenjang is a traditional fermented food that is widely consumed in Korea. The quality of doenjang varies considerably by its basic ingredients, species of microflora, and fermentation process. The classification of predefined metabolites (e.g. amino acids, organic acids, sugars and sugar derivatives, and fatty acids) in doenjang samples according to fermentation was performed by using GC‐FID and GC‐MS data sets with the application of a multivariate statistical method. RESULTS: The predominantly produced amino acids included alanine, valine, leucine, isoleucine, proline, glutamine, phenylalanine and lysine, showing remarkable increases in amounts during the later stages of fermentation. Carbonic acid, citric acid, lactic acid and pyrogultamic acid were identified as the major organic acids. Significant amounts of erythrose, xylitol, inositol and mannitol were detected during fermentation. Regarding fatty acids, relatively higher amounts of palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid were found in the doenjang at each fermentation time point. Principal component analysis (PCA) successfully demonstrated changes in composition patterns as well as differences in non‐volatile metabolites according to fermentation period. CONCLUSION: A set of metabolites could be determined representing the quality of doenjang during fermentation, and which might also be correlated with taste ingredients, flavour, nutrition, and physiology activities that are claimed to be dependent on the quality control of commercial doenjang. Copyright © 2010 Society of Chemical Industry     

浅析白酒酒体设计中对酸的认识

介绍了白酒中重要的呈味物质--有机酸的分类、生成途径、特征及有机酸对酒体风味的影响、作用和控制方法。     

Toxicity of Phenolic Compounds Extracted from Bark Residues of Different Ages

In Quebec, Canada, industrial bark wastelands cover several hundred hectares of land. Bark residue that has piled up for decades tends to remain free of vegetation for years. To assess the revegetation potential of such sites, we sought to determine those factors responsible for poor plant growth. Phenolic compounds from fresh to 20-year-old bark residues were extracted with four solvents and quantified by high-performance liquid chromatography (HPLC). We simulated solutions (mixtures of standard phenolic compounds) to evaluate the potential toxic effects of phenolic compounds on the rhizobial growth, germination index, plant growth, nodule number, and nitrogen fixation activity of two legume species under laboratory conditions. The concentration of individual phenolic compounds varied from none detected to 350 μg/g bark residue. The extracted phenolic compounds differed among solvents and bark residues. The highest concentration of total phenolic compounds was from fresh bark; most of these were soluble in water or 0.1 M NaOH. For older bark residues, the total phenolic content depended on solvent strength, generally in the order of 2.0 M NaOH > 0.1 M NaOH = hot water > cold water. The biological activity of the simulated bark extracts was not established with the rhizobial growth inhibition test but with the germination index and rhizobium–legume symbiosis tests. With these, the toxicity of the simulated phenolic extracts decreased from fresh to the older bark residues. Plant dry weight, nodule number, and nitrogen fixation activity of vetch (Vicia sativa L.) were less negatively affected by high concentrations of phenolics than birdsfoot trefoil (Lotus corniculatus L.), although birdsfoot trefoil grew at lower concentrations. The rhizobium–legume symbiosis has potential for revegetating bark wastelands with less than 1 year old and older bark residues.     

Short-Chain Fatty Acids Produced by Ruminococcaceae Mediate α-Linolenic Acid Promote Intestinal Stem Cells Proliferation

Scope : The proliferation and differentiation of intestinal stem cells (ISCs) are the basis of intestinal renewal and regeneration, and gut microbiota plays an important role in it. Dietary nutrition has the effect of regulating the activity of ISCs; however, the regulation effect of α-linolenic acid (ALA) has seldom been reported. Methods and Results : After intervening mice with different doses of ALA for 30 days, it is found that ALA (0.5 g kg^?1) promotes small intestinal and villus growth by activating the Wnt/β-catenin signaling pathway to stimulate the proliferation of ISCs. Furthermore, ALA administration increases the abundance of the Ruminococcaceae and Prevotellaceae, and promotes the production of short-chain fatty acids (SCFAs). Subsequent fecal transplantation and antibiotic experiments demonstrate that ALA on the proliferation of ISCs are gut microbiota dependent, among them, the functional microorganism may be derived from Ruminococcaceae. Administration of isobutyrate shows a similar effect to ALA in terms of promoting ISCs proliferation. Furthermore, ALA mitigates 5-fluorouracil-induced intestinal mucosal damage by promoting ISCs proliferation. Conclusion : These results indicate that SCFAs produced by Ruminococcaceae mediate ALA promote ISCs proliferation by activating the Wnt/β-catenin signaling pathway, and suggest the possibility of ALA as a prebiotic agent for the prevention and treatment of intestinal mucositis.     

A green approach for cohesive recycling and regeneration of electrode active materials from spent lithium-ion batteries

The implementation of the green energy transition by reducing reliance on fossil fuels has fueled the burgeoning demand for lithium-ion batteries in grid-level energy storage systems and electric vehicles. The growth of portable electronic devices has also contributed to this exponential demand, creating both logistical and environmental challenges in the supply of raw materials such as lithium and the management of end-of-life batteries. Current recycling methods for spent batteries are both energy-intensive and inefficient. To address these issues, a green approach using organic acid mixtures has been proposed to reclaim lithium from spent cathodes and recover and purify graphite from spent anodes, while also regenerating its structure. The effectiveness of this method is demonstrated through the use of organic acid mixtures to leach and reclaim lithium from NCM 622 batteries. On the anode side, a curing–leaching strategy using organic acids is employed to purify spent graphite, which is subsequently calcined to enhance its interlayer structure conducive to better intercalation of Li⁺ and improve electrochemical performance. Additionally, recovered graphite is tailored with carbon using water bath carbonization to repair structural defects caused by lithium intercalation and improve electrochemical performance while augmenting the regenerated graphite's quality, equipping it to be reused in batteries or upcycled applications.     

CO2 absorption kinetics and equilibrium solubility measurements in potassium salts of renewable amino acids from plant- and animal-protein

Aqueous solutions containing alkaline salts of natural amino acids, such as those from protein in plant seeds or high protein animal-based waste, are green CO₂-separation solvents. In the present work, potassium salts of nine such amino acids were chosen for an in-depth study: alanine, arginine, aspartic acid, glutamic acid, glycine, leucine, proline, serine, and valine. The kinetics of CO₂ absorption in aqueous solutions of these salts was studied using a stirred cell. From the measurements of the absorption rate at different salt concentrations (molarity 0.1 and higher), CO₂ partial pressures (5–25 kPa), and temperatures (298–308 K), values of the reaction order, rate constant, and activation energy were determined. Additionally, the liquid-side mass transfer coefficient (0.005 cm/s) was also found. Potassium salts of proline, glycine, and arginine were most reactive and, hence, were chosen for equilibrium study. The loading capacity of these salts was measured at 308 K in a vapour–liquid equilibrium setup at near-ambient pressure. On the contrary, the other chosen acids were comparatively less reactive with CO₂.     

冻干银鱼的营养价值与初步的感官评价

将新鲜银鱼-70℃速冻后冷冻干燥处理48 h,研究冻干过程中银鱼含水量的变化、冻干银鱼的外观及复水时间,比较冻干银鱼与烘干银鱼的氨基酸组成、粗多糖和4种微量元素的含量.结果显示:冻干银鱼的平均含水量为8.61%,外形、颜色与新鲜银鱼相近,复水性能比烘干银鱼好.冻干银鱼的总必需氨基酸、总氨基酸含量和必需氨基酸指数高于烘干银鱼.冻干银鱼的粗多糖得率低于烘干银鱼,但纯度较高.Fe、Cu、Mn、Zn 4种微量元素的含量没有明显差别.上述结果表明:冷冻干燥法加工的银鱼营养成分与烘干银鱼没有显著差别,但外形、颜色和复水性能明显优于烘干法加工的银鱼,是一种值得深入研究和推广的银鱼加工方法.     

气相色谱-质谱法测定人造奶油中的脂肪酸

采用氯仿、甲醇混合溶剂萃取人造奶油中的脂肪,并用氢氧化钾-甲醇法甲酯化,通过气相色谱-质谱法分析其脂肪酸成分,鉴定出12种化合物,其中主要以油酸(30.918%)、棕榈酸(53.456%)为主,占人造奶油总脂肪酸量的84.374%,亚油酸的含量已降低至7.817%.