Formation of alanine, α-aminobutyrate, acetate, and 2-butanol during cheese ripening by Pediococcus acidilactici FAM18098

There is limited information about the contribution of Pediococcus acidilactici, a nonstarter lactic acid bacteria, to cheese ripening and flavour development. Model Tilsit-type and Gruyère-type cheeses were produced using P. acidilactici FAM18098 as an adjunct. The adjunct did not influence the cheese manufacturing processes. The pediococcal log counts ranged from 7.0 to 8.0 cfu g-1 after 90 and 120 days of ripening. P. acidilactici produced ornithine, a result of arginine metabolism by the arginine deiminase pathway, and a-aminobutyrate and alanine while simultaneously metabolising serine and threonine. The analysis of the volatile compounds in the cheeses showed that higher acetate, 2-butanone, and 2-butanol levels and lower diacetyl levels were present in the cheeses produced with P. acidilactici than in the control cheeses. The study illustrates that P. acidilactici can influence amino acid metabolism in cheese; further, ornithine, a-aminobutyrate, and acetate can serve as indicators for the presence of this species. © 2019 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Serum Metabolites Responding in a Dose-Dependent Manner to the Intake of a High-Fat Meal in Normal Weight Healthy Men Are Associated with Obesity

Although the composition of the human blood metabolome is influenced both by the health status of the organism and its dietary behavior, the interaction between these two factors has been poorly characterized. This study makes use of a previously published randomized controlled crossover acute intervention to investigate whether the blood metabolome of 15 healthy normal weight (NW) and 17 obese (OB) men having ingested three doses (500, 1000, 1500 kcal) of a high-fat (HF) meal can be used to identify metabolites differentiating these two groups. Among the 1024 features showing a postprandial response, measured between 0 h and 6 h, in the NW group, 135 were dose-dependent. Among these 135 features, 52 had fasting values that were significantly different between NW and OB men, and, strikingly, they were all significantly higher in OB men. A subset of the 52 features was identified as amino acids (e.g., branched-chain amino acids) and amino acid derivatives. As the fasting concentration of most of these metabolites has already been associated with metabolic dysfunction, we propose that challenging normal weight healthy subjects with increasing caloric doses of test meals might allow for the identification of new fasting markers associated with obesity

Molecular effects of the consumption of margarine and butter varying in trans fat composition: a parallel human intervention study

BACKGROUND Whereas the dietary intake of industrial trans fatty acids (iTFA) has been specifically associated with inflammation, cardiovascular disease, and type 2 diabetes, understanding the impact of dietary fats on human health remains challenging owing to their complex composition and individual effects of their lipid components on metabolism. The aim of this study is to profile the composition of blood, measured by the fatty acid (FAs) profile and untargeted metabolome of serum and the transcriptome of blood cells, in order to identify molecular signatures that discriminate dietary fat intakes. METHODS In a parallel study, the molecular effects of consuming dairy fat containing ruminant TFA (rTFA) or margarine containing iTFA were investigated. Healthy volunteers (n = 42; 45-69 y) were randomly assigned to diets containing margarine without TFA as major source of fat (wTFA control group with 0.4 g TFA per 100 g margarine), margarine with iTFA (iTFA group with 4.1 g TFA per 100 g margarine), or butter with rTFA (rTFA group with 6.3 g TFA per 100 g butter) for 4 weeks. The amounts of test products were individually selected so that fat intake contributed to 30-33% of energy requirements and TFA in the rTFA and iTFA groups contributed to up to 2% of energy intake. Changes in fasting blood values of lipid profiles (GC with flame-ionization detection), metabolome profiles (LC-MS, GC-MS), and gene expression (microarray) were measured. RESULTS Eighteen FAs, as well as 242 additional features measured by LC-MS (185) and GC-MS (54) showed significantly different responses to the diets (P$_{FDR-adjusted}$ < 0.05), mainly distinguishing butter from the margarine diets while gene expression was not differentially affected. The most abundant TFA in the butter, i.e. TFA containing (E)-octadec-11-enoic acid (C18:1 t11; trans vaccenic acid), and margarines, i.e. TFA containing (E)-octadec-9-enoic acid (C18:1 t9; elaidic acid) were reflected in the significantly different serum levels of TFAs measured after the dietary interventions. CONCLUSIONS The untargeted serum metabolome differentiates margarine from butter intake although the identification of the discriminating features remains a bottleneck. The targeted serum FA profile provides detailed information on specific molecules differentiating not only butter from margarine intake but also diets with different content of iTFAs in margarine. TRIAL REGISTRATION ClinicalTrials.gov NCT00933322

Molecular effects of the consumption of margarine and butter varying in trans fat composition: a parallel human intervention study.

BACKGROUND Whereas the dietary intake of industrial trans fatty acids (iTFA) has been specifically associated with inflammation, cardiovascular disease, and type 2 diabetes, understanding the impact of dietary fats on human health remains challenging owing to their complex composition and individual effects of their lipid components on metabolism. The aim of this study is to profile the composition of blood, measured by the fatty acid (FAs) profile and untargeted metabolome of serum and the transcriptome of blood cells, in order to identify molecular signatures that discriminate dietary fat intakes. METHODS In a parallel study, the molecular effects of consuming dairy fat containing ruminant TFA (rTFA) or margarine containing iTFA were investigated. Healthy volunteers (n = 42; 45-69 y) were randomly assigned to diets containing margarine without TFA as major source of fat (wTFA control group with 0.4 g TFA per 100 g margarine), margarine with iTFA (iTFA group with 4.1 g TFA per 100 g margarine), or butter with rTFA (rTFA group with 6.3 g TFA per 100 g butter) for 4 weeks. The amounts of test products were individually selected so that fat intake contributed to 30-33% of energy requirements and TFA in the rTFA and iTFA groups contributed to up to 2% of energy intake. Changes in fasting blood values of lipid profiles (GC with flame-ionization detection), metabolome profiles (LC-MS, GC-MS), and gene expression (microarray) were measured. RESULTS Eighteen FAs, as well as 242 additional features measured by LC-MS (185) and GC-MS (54) showed significantly different responses to the diets (PFDR-adjusted < 0.05), mainly distinguishing butter from the margarine diets while gene expression was not differentially affected. The most abundant TFA in the butter, i.e. TFA containing (E)-octadec-11-enoic acid (C18:1 t11; trans vaccenic acid), and margarines, i.e. TFA containing (E)-octadec-9-enoic acid (C18:1 t9; elaidic acid) were reflected in the significantly different serum levels of TFAs measured after the dietary interventions. CONCLUSIONS The untargeted serum metabolome differentiates margarine from butter intake although the identification of the discriminating features remains a bottleneck. The targeted serum FA profile provides detailed information on specific molecules differentiating not only butter from margarine intake but also diets with different content of iTFAs in margarine. TRIAL REGISTRATION ClinicalTrials.gov NCT00933322

Influence of a dry fractionation of butterfat on the content of fatty acids including conjugated linoleic acids

There is a growing demand among consumers for food products with natural nutritional-physiological advantages over comparable conventional products. As part of an EU project, a process using dry fractionation is evaluated that enables the targeted lowinput enrichment of conjugated linoleic acids (CLA) in milk fat. Furthermore, the distribution of CLA isomers in the fat fractions was analysed. In the olein fraction for highland butter a CLA enrichment of 15.3% was obtained. The yield of the CLA rich olein fraction was 44.5% of the total amount of olein and stearin. There were significant increases during the first fractionation step of highland butter for the concentration of the CLA isomer cis-9, trans-11 (P £ 0.05) and during the second fractionation step for the concentration of CLA isomers cis-9, trans-11; trans-11, cis-13 (P £ 0.05) and trans-7, cis- 9 (P £ 0.01). Experiments carried out demonstrate that the selected physical separation process enables CLA enrichment but the increase is too minor to achieve any decisive positive impact on human health and therefore too costly as an industrial CLA enrichment process

ACE-inhibitory activity and ACE-inhibiting peptides in different cheese varieties

During the ripening of cheese, a large number of peptides are formed from casein. Some of these peptides have been shown to exert an antihypertensive effect due to their angiotensin-I-converting enzyme (ACE)-inhibitory activity. Recently, several studies have investigated the ACE-inhibiting potential of cheese, and various ACE-inhibiting peptides have been isolated and identified from different cheese varieties. The present review focuses on the occurrence of two tripeptides, Val-Pro-Pro and Ile-Pro-Pro, in cheese. These tripeptides were first described in fermented-milk products and have been demonstrated to exert a blood pressure-lowering effect in humans with mild hypertension. The influence of cheesemaking and ripening on the release of ACE-inhibiting peptides is revealed. Finally, the antihypertensive potential of cheese with high ACE-inhibitory activity is discussed with regard to the bioavailability of the peptides involved

Composition en acides gras du lait de montagne suisse. Variations saisonnières

The influence of typical feeds from five mountain regions of Switzerland (altitude of grass-based feed (GBF) during the summer and winter seasons: 1247 ($\pm$ 465) m and 1136 ($\pm$ 310) m, respectively) on the fatty acid (FA) composition of bovine milk fat was studied over one year (from May 2004 to April 2005). Compared with winter, summer milk had a significantly lower concentration of saturated FA (SFA) (–8.6%) and significantly higher contents of monounsaturated FA (MUFA) (+19.9%), polyunsaturated FA (PUFA) (+21.7%), conjugated linoleic acid (CLA) (+70.1%), and trans FA other than CLA (+56.7%). Summer and winter milk from mountains did not significantly differ with respect to the contents of branched, $n$-3 and $n$-6 FA. However, the content of the main $n$-3 FA ($\alpha$-linolenic acid) was significantly higher in summer than in winter milk and its content was positively correlated with increasing percentages of GBF and altitude.L'influence d'un affouragement typique des régions de montagne suisses (cinq régions ; altitude du fourrage à base d'herbe durant les saisons estivale et hivernale: 1247 ($\pm$ 465) m et 1136 ($\pm$ 310) m, respectivement) sur la composition en acides gras du lait de vache a été étudiée pendant une année (de mai 2004 à avril 2005). Comparée à l'hiver, la matière grasse du lait d'été avait des concentrations significativement plus basses en acides gras saturés (– 8,6 %) et plus élevées en monoinsaturés (+19,9 %), polyinsaturés (+21,7 %), acides linoléiques conjugués (ALC) (+70,1 %) et en acides gras trans (+56,7 %, ALC non inclus). Les concentrations en acides gras ramifiés, $n$-3 et $n$-6 du lait d'été et d'hiver n'étaient pas significativement différentes. Cependant, la concentration de l'acide gras $n$-3 principal de la matière grasse du lait, l'acide $\alpha$-linolénique, était significativement plus élevée dans les laits d'été que dans ceux d'hiver et était positivement corrélée avec le pourcentage de fourrage à base d'herbe et avec l'altitude