Chemical composition of home-made goats’ milk cake

Abstract

Goats’ milk cake is a fresh cheese-like product, traditionally produced and consumed for centuries in Yunnan, a south-western province of China. It is made by acidifying the milk using acidulant extracted from the plant Marsdenia tenacissima. Nine goats’ milk cake (GMC) and four cows’ milk cake (CMC) samples collected from different households in Yunnan province were analysed for gross composition, minerals, protein profiles and fatty acid profiles. The pHs of GMC and CMC samples were 5.01±0.96 and 5.59±0.85, total solids 48.44±1.56 and 46.59±3.85, fat 23.08±1.61 and 22.49±3.63, protein 20.41±1.15 and 19.29±1.48, ash 1.91±0.08 and 1.79±0.10 and lactose 3.03±1.23 and 3.02±1.61%, respectively. The average contents of calcium, phosphorous, potassium, and sulphur of GMC were 0.60±0.07, 0.52±0.05, 0.13±0.02, and 0.17±0.01 g/100 g and those of CMC were 0.54±0.11, 0.46±0.05, 0.10±0.03, and 0.16±0.00 g/100 g, respectively. The major protein fraction in GMC samples was β-casein whereas that in CMC samples was αs-casein. The major fatty acids present in GMC and CMC were saturated. The only unsaturated fatty acid present in GMC in significant quantity was oleic acid (6.48±1.02%). Variations in chemical composition of these goats’ milk cakes might be due to lack of manufacturing standards, which may require further studies.

Download

Stereochemistry of erythro- and threo-syringylglycerol-8-O-4΄- (sinapyl alcohol) ethers and their enzymatic formation with optical activity in Eucommia ulmoides

Abstract

In this study an enzymatic system, horseradish peroxidase (HRP)-hydrogen peroxide was used as catalysts for the enzymatic formation of enantiospecific syringulglycerol-8-O-4′ (sinapyl alcohol) ethers (SGSEs) from enzyme preparations of Eucommia ulmoides with sinapyl alcohol (SA) as a monolignol precursor. Reversed phase HPLC analysis of the erythro- and threo-SGSE showed that the ratio of erythro: threo was 47: 53. Both isomers were isolated by HPLC and their structural confirmation was done by 1H NMR spectra. Chiral column HPLC analysis of the erythro- and threo-SGSE showed that their enantiomeric compositions were as follows: (+)- erythro: (-)-erythro = 46.7:53.3 (6.6% e.e), and (+)-threo: (-)-threo = 45.2: 54.8 (9.6% e.e). To elucidate the stereochemistry of erythro and threo- SGSEs, we have determined absolute configurations of the four stereoisomers, (+)-erythro-, (-)-erythro-, (+)-threo-, and (-)-threo- SGSEs as (7R, 8S), (7S, 8R), (7S, 8S), and (7R, 8R), respectively, by Mosher’s method through the 1H NMR spectroscopy of (+)-(R)-α-methoxy- α- trifluoromethylphenylacetate (MTPA) esters of α, γ and γ’ positions.

Download

Isolation and functional characterization of a Xoral tissue-speciWc R2R3 MYB regulator from tobacco

Abstract:

Tobacco is a commonly used heterologous system for studying combinatorial regulation of the Xavonoid biosynthetic pathway by the bHLH–MYB transcription factor (TF) complex in plants. However, little is known about the endogenous tobacco bHLH and MYB TFs involved in the pathway. Ectopic expression in tobacco of heterologous bHLH TF genes, such as maize Lc, leads to increased anthocyanin production in the reproductive tissues, suggesting the presence of a reproductive tissue-specific MYB TF that interacts with the Lc-like bHLH TFs. We isolated a gene (NtAn2) encoding a R2R3 MYB TF from developing tobacco Xowers. NtAn2 shares high sequence homology with other known Xavonoid-related MYB TFs and is mostly expressed in developing Xowers. Constitutive ectopic expression of NtAn2 induces whole-plant anthocyanin

production in tobacco and Arabidopsis. In transgenic tobacco and Arabidopsis expressing NtAn2, both subsets of early and late Xavonoid pathway genes are up-regulated. Suppression of NtAn2 by RNAi in tobacco resulted in a white-Xowered phenotype and the inhibition of the late pathway genes. Yeast two-hybrid assays demonstrated that NtAn2 can interact with Wve heterologous bHLH TFs known to induce anthocyanin synthesis in other species including maize, perilla, snapdragon and Arabidopsis. Bimolecular Xuorescent complementation using split YFP demonstrated that NtAn2 interacts with Lc in tobacco cells

and that the complex is localized to nuclei. Transient co-expression of NtAn2 and Lc or Arabidopsis TT8 in

tobacco protoplasts activated the promoters of two key Xavonoid pathway genes, chalcone synthase and dihydroXavonol reductase. These results suggest that NtAn2 is a key gene controlling anthocyanin production in reproductive tissues of tobacco.

Download