Quantitative assessment of lactate and progerin production in normal human cutaneous cells during normal ageing: effect of an Alaria esculenta extract

Anti-ageing products are of a great importance in cosmetic fields. However, even if numerous strategies have been proposed to fight against skin ageing or to minimize its aesthetic impact since the beginning of the 'scientific cosmetology' era, the products basing their efficacy on the observation of pathological situations are rare. The most obvious pathology linked to the ageing of skin (notably) consists in the Hutchinson-Gilford Progeria Syndrome (HGPS), a rare disorder characterized by accelerated ageing and early death. In this disease the lamin A, a protein participating (with others lamins) in the formation of the nuclear lamina and implicated in nuclear stability, chromatin structure and gene expression, is present in a truncated version called progerin. In this study, we have examined the lactate and the progerin production of human normal cutaneous cells issued from subjects of different ages. Using a sensitive and specific progerin ELISA assay developed in house, we so provide the first quantitative demonstration of an increased progerin expression and lactate production in skin during ageing. Moreover, we have also demonstrated that in the selected experimental conditions, it was possible to down-regulate the progerin production of aged cells by using an algae extract. As this extract, an Alaria esculenta extract, could be used in cosmetic formulations, we suggest that a better understanding of the skin pathologies could be a useful tool in developing efficient active compounds, attractive for but not limited to cosmetic purposes.     

Control of Listeria monocytogenes in ready-to-eat meats containing sodium levulinate, sodium lactate, or a combination of sodium lactate and sodium diacetate

ABSTRACT:  This study investigated the use of sodium levulinate to prevent outgrowth of Listeria monocytogenes in refrigerated ready-to-eat (RTE) meat products. Turkey breast roll and bologna were formulated to contain 1%, 2%, or 3% (w/w) sodium levulinate, 2% sodium lactate, a 2% combination of sodium lactate and sodium diacetate (1.875% sodium lactate and 0.125% sodium diacetate), or no antimicrobial (control). Samples of the RTE products were sliced, inoculated with 10² to 10³ CFU/cm² of a 5-strain cocktail of L. monocytogenes , vacuum packaged, and stored at refrigeration temperature for 0 to 12 wk. Counts reached 10⁸ CFU/cm² on control turkey roll product after 8 wk, and over 10⁷ CFU/cm² on control bologna after 12 wk. Addition of 2% or more sodium levulinate to turkey roll and 1% or more sodium levulinate to bologna completely prevented growth of L. monocytogenes during 12 wk of refrigerated storage. A consumer taste panel with pathogen-free samples found no differences in the overall liking among the preparations of turkey roll or among preparations of bologna. These results show that sodium levulinate is at least as effective at inhibiting outgrowth of L. monocytogenes in RTE meat products as the current industry standards of lactate or lactate and diacetate, and levulinate addition does not alter the overall liking of the RTE meat products.     

Minimum inhibitory concentration (MIC) of sodium lactate for pathogens and spoilage organisms occurring in meat products

Pathogens and spoilage organisms occuring in meat products were screened in laboratory media, according to a method of Eklund (1983), in order to determine the specific inhibitory effect of lactate on growth of these microorganisms under optimum growth conditions (pH 6.5, 20°C). In general, Gram-positive bacteria were more sensitive towards lactate than Gram-negative bacteria. It was shown especially, that strains that were able to grow at water activities of 0.95 and below in the presence of NaCl (Staphylococcus aureus, Listeria monocytogenes, Brochothrix thermosphacta) were inhibited by sodium lactate (NaL). It appeared, that yeasts were resistant to large amounts of NaL (> 10% w/v). However, NaL had a specific inhibitory effect on growth of these organisms when compared to the effect of NaCl. These results indicate that lactate addition to food products with a pH near neutrality offers good prospects for shelf life prolongation.     

小曲白酒生产中乙酸乙酯、乳酸乙酯影响因素的探讨

为了提高小曲白酒的质量和产量，对小曲白酒生产中乙酸乙酯、乳酸乙酯的影响因素进行了跟踪分析。结果表明，主要影响因素有：(1)培菌温度，应坚持低温培菌，控制出箱温度不超过38℃；(2)糖化醅水分，要求水分为53％～61％；(3)糖分，要求为2％～4％；(4)入池温度，控制在21～22℃之间；(5)发酵升温，前期发酵温度不能上升过快。(小雨)     

乳酸盐通量及其控制分析:食品功能的定量化评价方法

目的:食品对机体的影响主要表现为对代谢和代谢网络的影响,本实验旨在研究食品对机体代谢作用的定量化评价方法。方法:通过对志愿者外周血采样,首先研究4 种生理状态(基础状态、学习状态、运动状态和发烧状态)下,乳酸盐代谢通量的变化,同时研究中心代谢途径中的15 种酶对乳酸盐代谢通量的控制作用;采用相关分析和主成分分析相结合的方法,研究酶的表达(或合成)量对乳酸盐代谢通量的作用,确定主成分及各种酶的控制系数。另招募健康志愿者,采集其食用大米变性淀粉前后的外周血样,运用已建立的代谢通量模型及控制分析方法对变性淀粉的功能性进行评价。结果:4种状态下乳酸盐代谢通量各不相同,由小到大依次为:基础状态、学习状态、运动状态和发烧状态,4种生理状态下机体内的分解代谢依次增强,可见乳酸盐代谢通量实质上反映了机体分解代谢(氧化磷酸化供能)的强弱。丙酮酸激酶(pyruvate kinase,PK,Cp PK=0.221 6),丙酮酸脱氢酶复合物(pyruvate dehydrogenase complex,PDHC,Cp PDHC=0.206 4),乳酸脱氢酶(lactate dehydrogenase,LDH,Cp LDH=0.162 6),转酮酶(transketolase,TKL,Cp TKL=0.206 0)对乳酸盐代谢通量起到主要作用,其中,PK的控制作用最强。志愿者食用变性淀粉后,乳酸盐通量增强,分解代谢增强而合成代谢减弱;PK的基因表达(合成)量显著增加(P=0.010.05),PDHC的基因表达(合成)量极显著降低(P=0.0030.01),说明所测酶的表达量与所预测的乳酸盐通量之间的拟合程度较好。结论:本实验建立的评价方法可以通过采集适量的外周血对食用食品后的人体代谢作用进行定量化评价。     

Microbiological and Sensory Changes in Minced Beef Treated with Potassium Lactate and Sodium Diacetate during Refrigerated Storage

The effect of potassium lactate and sodium diacetate on the microbiological changes and sensory properties of vacuum-packaged minced beef was investigated. The meat samples both with a preservative (in the amounts 0.65% and 1.3%) and without were stored at temperatures of 0–1°C and 5–6°C. The influence of storage time on changes in total bacteria count (TBC), lactic acid bacteria (LAB), Brochothrix thermosphacta, and the microbes of the Enterobacteriaceae family was investigated, as well as changes in pH and sensory quality. It was found that the addition of the preservative to the minced meat caused a significant extension (p < 0.05) of the lag phase and an inhibition of microbial growth rate, depending on temperature, storage time, and its concentration. The antibacterial effect was significantly higher (p < 0.05) at a temperature of 0–1°C than at 5–6°C and most susceptible to it were the bacteria belonging to the Enterobacteriaceae. The study results showed that the minced beef containing the preservative which had been vacuum stored at 0–1°C, presented a better sensory quality and had a shelf-life of about 6 days longer, in relation to the quality and shelf-life of the control samples. For each of the refrigeration storage temperatures however, there was no statistically significant change (p < 0.05) in the pH for the various storage periods and preservative quantities present.     

Antibacterial Action of Haw Pectic Oligosaccharides

Haw pectic oligosaccharides, lactic acid, sodium lactate, and tea polyphenol showed dose and pH dependent antibacterial activity against E. coli. The activity of haw pectic oligosaccharides could be enhanced by combination with lactic acid, sodium lactate, or tea polyphenol. However, combination of haw pectic oligosaccharides with nisin resulted in no significant enhancement of antibacterial activity against E. coli. These results revealed that haw pectic oligosaccharides is valuable as a food preservative, and lactic acid or sodium lactate could be used to enhance its antibacterial activity, allowing for further improvement in its efficiency, likely leading to a reduction in the dosage necessary for food preservation.     

以红曲霉酯化酶催化合成乳酸乙酯

利用自汾酒大曲中分离获得的产酯能力较高的红曲霉菌株,采用正交试验法,以酯化酶活性为检测指标,优化了发酵培养基配方和培养条件,确定了最佳发酵培养基成分质量配比为麸皮:水=1:1;最佳发酵条件为:红曲霉接种量为1%,发酵温度为30℃,发酵4 d,制得酯化酶酶制剂。在此基础上,采用响应面优化法对其酯化酶的催化条件进行了优化,确定了最佳催化条件为:乙醇和乳酸的摩尔比为6,加酶量1.5%,反应时间60h,反应温度30℃,乳酸乙酯生成量可达到3.38 g/L。     

The effect of NaCl-free processing and high pressure on the fate of Listeria monocytogenes and Salmonella on sliced smoked dry-cured ham

NaCl is an important multifunctional ingredient applied in dry-cured ham elaboration. However, its excessive intake has been linked to serious cardiovascular diseases causing a recent increase in the development of reduced salt products. In the present study Listeria monocytogenes and Salmonella, food-borne pathogens which can cross-contaminate post processed products, were spiked with < 100 CFU/g on slices of both standard (S) and NaCl-free processed (F) (elaborated with KCl + potassium lactate instead of NaCl) smoked dry-cured ham. Although L. monocytogenes and Salmonella counts decreased faster in S ham, pathogens were present in both types of non-pressure treated ham during the entire refrigerated storage period (112 days). Pressurisation at 600 MPa for 5 min caused the elimination of both pathogens in S ham after 14 days. In contrast, Salmonella and L. monocytogenes were present in F ham until days 28 and 56, respectively, indicating that the NaCl-free processed dry-cured ham had lower stability than standard smoked dry-cured ham.