Recovery of n-3 polyunsaturated fatty acids and conjugated linoleic acids in ripened cheese obtained from milk of cows fed different levels of extruded flaxseed

The aim of the study was to investigate whether the addition of extruded flaxseed (EF) in dairy cow diets had an effect on milk fat and individual fatty acids (FA) recovery in cheese after 90 d of ripening. Eighteen Holstein-Friesian cows, divided into 3 experimental groups (6 cows/group), were fed 3 isonitrogenous and isoenergetic diets with 0 (CTR), 500 (EF500), or 1,000 g/d (EF1000) of EF in 3 subsequent periods (2 wk/each), following a 3 × 3 Latin square design. Dry matter intake (DMI) and milk yield were recorded daily. Individual milk samples were collected on d 7 and 13 of each period to determine proximate and FA composition. Eighteen cheese-making sessions (2 for each group and period) were carried out, using a representative pooled milk sample obtained from the 6 cows of each group (10 L). At 90 d of ripening, cheeses were analyzed for proximate and FA composition. Cheese yield was computed as the ratio between the weights of ripened cheese and processed milk. Recoveries of fat, individual FA, and grouped FA were computed as the ratio between the corresponding weights in cheese and in milk. Inclusion of EF did not affect DMI, milk yield, or milk composition. Compared with CTR, the 2 diets containing EF increased the proportion of C18:3n-3 and total n-3 FA, in both milk and cheese. Cheese yield and cheese fat percentage did not differ among diets. Likewise, milk fat recovery in cheese was comparable in the 3 treatments and averaged 0.85. The recoveries of individual FA were, for the most part, not dissimilar from fat recovery, except for short-chain saturated FA (from 0.38 for C4:0 to 0.80 for C13:0), some long-chain saturated FA (0.56 and 0.62 for C20:0 and C21:0, respectively), and for C18:3n-6 (1.65). The recovery of saturated FA was lower than that of monounsaturated FA, whereas recovery of polyunsaturated FA was intermediate. Compared with medium- and long-chain FA, short-chain FA were recovered to a smaller extent in cheese. No differences in recovery were found between n-6 and n-3 FA. In conclusion, FA have different recoveries during cheese-making, with lower values for the short-chain compared with long-chain FA, and for saturated FA compared with unsaturated FA. The addition of EF in dairy cow diets did not influence cheese yield or fat recovery in cheese, irrespective of the inclusion level. The experiment confirmed that feeding cows with EF represents a successful strategy for improving the FA profile of dairy products, through an increase of n-3 FA.     

Physicochemical properties of steamed bread fortified with ground linseed (Linum usitatissimum)

Chinese steamed bread (CSB) is a staple food among Asian populations. Linseed (Linum usitatissimum) is an emerging ‘healthy’ food ingredient rich in a range of bioactive components. Ground linseeds were incorporated in northern style CSB formulation up to 20%. Various physico-chemical, nutritional and sensory properties of the resulting CSB were studied. Linseed addition decreased the specific volume and spread ratio of CSB, while increasing the hardness and chewiness in a dose-dependent manner. Linseed addition up to 15% little affected the overall sensory acceptability of CSB. Nutritionally, linseed addition increased the in vitro antioxidant activities of CSB, while decreasing in vitro starch digestibility and expected glycaemic index. It may be concluded that linseed has the potential to enhance the nutritional quality of CSB without negatively affecting the eating quality.     

Antioxidant and antibacterial activities of peptide fractions from flaxseed protein hydrolysed by protease from Bacillus altitudinis HK02

Flaxseed protein (FP) hydrolysates by crude protease of strain Bacillus altitudinis HK02 were further separated into five fractions by ultrafiltration membranes with a molecular weight cut‐off of 10, 5, 3 and 1 kDa for the analysis of antioxidant activities and antibacterial ability. The results demonstrated that the fraction of 1‐ to 3‐kDa peptides exhibited higher antioxidant activities on the free radical‐scavenging ability and the reducing power than those of Vit C, Vit E, BHA and other fractions. The fraction with a low molecular weight (<1 kDa) of peptides demonstrated the highest ferrous ion‐chelating ability and a higher inhibition of lipid peroxidation than BHA and other fractions. Moreover, it also exhibited the best growth inhibition of Pseudomonas aeruginosa and Escherichia coli. The results, including the concentration‐dependent effect of peptides fractions, demonstrated that it is feasible to derive functional ingredients of natural antioxidants along with antimicrobial activity from FPs hydrolysed by protease from B. altitudinis HK02.     

溶剂法提取亚麻籽木脂素(SDG)工艺优化研究

研究了溶剂法提取亚麻籽中木脂素的工艺,确定了单因素试验的最佳溶剂系统为70%的乙醇,提取温度为室温,时间为24 h。以木脂素得率为指标,采用二次正交旋转回归试验对溶剂法提取亚麻籽木脂素提取工艺进行优化,求得了二次正交旋转回归方程,确定了影响溶剂法木脂素得率的各因素的主次顺序依次为:提取时间、提取温度、乙醇浓度。用统计寻优方法进行方案寻优,可得乙醇浓度为70%、提取时间为28 h、提取温度为40℃时,木脂素得率最高为9.25%。     

Metal binding novel flaxseed peptides (linusorbs)

Linusorbs (LOs; a.k.a. cyclolinopeptides) are naturally occurring orbitides derived from flaxseed. These compounds consist of 8–10 amino acid residues, which are linked via an N ‐ to C‐terminal peptide bond with molecular masses of approximately 1 kDa. The LO circular structure makes them candidates for metal binding studies. Flaxseed extracts are known to suppress Pb and Cd toxicity. Hence, four metal salts surveyed include Zn(CH₃COO)₂, ZnSO₄, Pb(CH₃COO)₂ and Cd(NO₃)₂ with pure LOs 1–5 . Proton NMR spectra indicated interaction of LOs with metal salts in solution and were used to determine impacts of methionine oxidation on interactions with metal ions. The methyl group of methionine S,S ‐ dioxide of related LOs did not show the same shift in the presence of Zn(CH₃COO)₂ and Pb(CH₃COO)₂ observed in their methionine S ‐ oxide analogues. Metal complexes were observed forming at 10^?2 m to 10^?4 m but not at lower concentrations (10^?5 m to 10^?8 m ). Mass spectrometry data confirmed that metal binding strength varied by metal in the order Zn(CH₃COO)₂<Pb(CH₃COO)₂<ZnSO₄<Cd(NO₃)₂.     

脱毒亚麻籽粕粉对面包品质影响的研究

将脱毒亚麻籽粕粉按一定比例添加到高筋粉中,探讨其对面团流变学特性、面团微观结构、面包烘焙特性及面包贮存过程中老化程度的影响.结果表明,挤压处理使有毒成分生氰糖苷含量显著减少;随着亚麻籽粕粉添加量的增加,面团吸水率、弱化度增加,面团形成时间、稳定时间、粉质评价值降低,面团韧性、抗延伸阻力、延伸性、粉力降低;面团的微观结构发生破坏;添加1%-5%的亚麻籽粕粉提高面包的感官评分和比容,同时具有抗老化作用,面包的硬度和弹性没有明显变化,延长了产品的货架寿命.     

亚麻籽面包的制作

本文研究了添加亚麻籽粉、亚麻籽壳、亚麻籽仁的营养面包的研制,通过实施确定了亚麻籽粉、亚麻籽壳、亚麻籽仁的添加方式和最佳添加比例。     

油料种子中的抗氧化活性成分

本文围绕五种油料作物的种子，主要对它们中抗氧化活性物质的种类、含量、分布及应用的研究情况作了概述。它们的加工副产物町作为天然抗氧化物质的来源加以开发应用。