Daniel Wechsler

Effect of dietary alpine butter rich in conjugated linoleic acid on milk fat composition of lactating sows

Multiparous sows (n 17) were included in a controlled cross-over-study in order to investigate the influence of a natural source of conjugated linoleic acid (CLA) (alpine butter) on the milk fatty acid composition of lactating sows (as an animal model for lactating women) and on the growth performance of their progeny. The usual fat source of a standard lactation diet was replaced by either CLA-rich alpine butter or margarine (control diet). Compared with the margarine diet, feeding the alpine butter-supplemented diet increased (P 0.05) affected. Growth performance of the progeny was similar for both dietary treatments. In summary, the findings show that adding alpine butter to the diet does not provoke a milk fat depression and does not alter the composition of total SFA, MUFA and PUFA in sow milk but increases its CLA concentration.

The Histidine Decarboxylase Gene Cluster of Lactobacillus parabuchneri Was Gained by Horizontal Gene Transfer and Is Mobile within the Species

Histamine in food can cause intolerance reactions in consumers. Lactobacillus parabuchneri (L. parabuchneri) is one of the major causes of elevated histamine levels in cheese. Despite its significant economic impact and negative influence on human health, no genomic study has been published so far. We sequenced and analyzed 18 L. parabuchneri strains of which 12 were histamine positive and 6 were histamine negative. We determined the complete genome of the histamine positive strain FAM21731 with PacBio as well as Illumina and the genomes of the remaining 17 strains using the Illumina technology. We developed the synteny aware ortholog finding algorithm SynOrf to compare the genomes and we show that the histidine decarboxylase (HDC) gene cluster is located in a genomic island. It is very likely that the HDC gene cluster was transferred from other lactobacilli, as it is highly conserved within several lactobacilli species. Furthermore, we have evidence that the HDC gene cluster was transferred within the L. parabuchneri species.

Iodine in Swiss milk depending on production (conventional versus organic) and on processing (raw versus UHT) and the contribution of milk to the human iodine supply

The iodine content in milk depends on various factors, including the season, production system, and location of milk production. The aim of this study was 1) to obtain data on the iodine concentration of conventional and organically produced milk and according to seasons; 2) to compare these actual data with previous measurement data; 3) to study the influence of UHT treatment on the iodine content and 4) to estimate the contribution of organic and conventional milk to the consumers iodine intake. A total of 110 samples of conventional and organic ultra-heat treated (UHT) whole milk were collected in the period between 1 May 2013 and 30 April 2014 from two large-scale companies, processing milk from two regions in Switzerland. The iodine concentration in organic milk (average 71 ± 25 μg/l) was significantly lower than in conventional milk (average 111 ± 26 μg/l) and varied between suppliers. Milk iodine concentration varied according to the month of collection in organic and conventionally produced milk, with lowest values between August and October (organic milk 42 μg/l; conventional milk 75 μg/l) and highest values in January (organic milk 99 μg/l; conventional milk 145 μg/l). Heat treatment did not influence iodine concentration. Since milk and dairy products are significant source of food-related iodine intake in Switzerland, consumers who prefer organic milk and dairy products are likely to have an inferior iodine status.

Validated method for the determination of propane-1,2-diol, butane-2,3-diol, and propane-1,3-diol in cheese and bacterial cultures using phenylboronic esterification and GC–MS

A simple, fast, sensitive, and robust gas chromatography-mass spectrometry (GC-MS) method for the simultaneous determination of propane-1,2-diol, butane-2,3-diol, and propane-1,3-diol in cheese and bacterial cultures was developed. Target analytes were extracted and transformed into their phenylboronic esters prior to analysis. The method showed good sensitivity, without carryover between the samples. The detection limits for propane-1,2-diol, butane-2,3-diol, and propane-1,3-diol in cheese samples were 0.26, 0.02, and 0.11mgkg-1, respectively, and for bacterial culture samples were 1.32, 0.09, and 0.54mgkg-1, respectively. The Horwitz ratio showed good precision for all analytes (<0.45). The calibrated range in cheese for all analytes was very broad, from 0 to 1000mgkg-1, and in bacterial cultures was from 0 to 5000mgkg-1 with R2>0.9991. The results confirm excellent applicability of the proposed method for the determination of the target metabolites in cheese and bacterial culture samples.

Enlightening the Lactate Degradation Processes in Cheese and Bacterial Cultures Using Phenylboronic Esterification and GC-MS

Infoodproduction, fermentationplaysakeyroleforpreserving food. At the same time, the process can be used to achieve the desired qualities of aroma, taste and texture. For example, for various cheeses, the eye formation is important, which is caused by the release of carbon dioxide during the ripening process. The bacteria used for this have a multitude of metabolic activities that can also release other gases. Some of the degradation pathways lead to the formation of diols. Lactobacillus parabuchneri is an interesting example for such a pathway, because it canmetabolize lactate to propane-1,2-diol with simultaneous release of acetate and carbon dioxide. Lactobacillus buchneri, on the other hand, produces propane-1,3-diol during the co-fermentation of carbohydrates and glycerine. The 2,3-butanediol fermentation is a way of breaking down carbohydrates to produce energy under anoxic conditions. The pathways that convert lactate into acetate under anaerobic conditions are not well understood at the molecular level. A sensitive method was therefore developed and validated for the simultaneous quantitative measurement of the metabolites propane-1,2-diol, butane-2,3-diol, and propane1,3-diol in cheese and bacterial cultures. In a first step, the diols are extracted in water and esterified directly in the extract with the aid of phenylboronic acid. After extraction with toluene, the resulting phenylboronic esters are measured directly using GCMS in selected-ion monitoring (SIM) mode with an external calibration using butane-1,2-diol as the internal standard. The method is simple, fast, robust, allows precise measurements in the mg/kg range and can be used in complex matrices due to selective double extraction and is therefore also of interest for plant and non-dairy food fermentation.