Volatile fraction of commercial thyme honeys produced in Mediterranean regions and key volatile compounds for geographical discrimination: A chemometric approach

The aim of the present study was to investigate the volatile fraction and discriminate 34 commercial thyme honeys from Morocco, Egypt, Spain, and Greece according to geographical origin, using key volatile compounds in combination with chemometrics. Sixty-two volatile compounds belonging to different classes were identified and semi-quantified using headspace solid phase micro-extraction coupled to gas chromatography/mass spectrometry (HS-SPME-GC/MS). Applying chemometric analyses to 17 volatiles (p < 0.05), honeys were successfully discriminated according to geographical origin. Correct classification rate was 88.2% using the cross-validation method. Volatile compounds proved to be a powerful tool for discriminating commercial thyme honeys from different countries.     

Degradation Kinetics and Storage Stability of Vacuum Spray-Dried Micro Wet-Milled Orange Juice (<Emphasis Type="Italic">Citrus unshiu</Emphasis>) Powder

The aim of this work was to evaluate the degradation kinetics and stability of micro wet milled orange juice powders obtained by vacuum spray drying, using maltodextrin as a carrier agent. Powders were produced with four combinations of orange juice solids/maltodextrin solids 60:40, 50:50, 40:60, and 30:70 by weight. Ascorbic acid degradation, color, and antioxidant activity of powders were evaluated throughout 90 days. Powders were stored at 10, 25, and 35 °C and relative humidity of 33%. Temperature and storage time negatively influenced the stability of ascorbic acid and color, whereas antioxidant activity increased at the beginning of storage at a higher temperature then decreased slightly after 60 days. For stability study, powders were stored at different water activities (0.11 to 0.84) in order to determine the plasticizing effects of water on glass transition temperature. Both water activity and glass transition temperature were used to predict the critical conditions for storage. Vacuum spray dried powder produced with a ratio of 30:70 (orange juice solids/maltodextrin solids) was considered as the most stable, since it showed highest critical water activity (a_w?=?0.61) and lowest moisture content (0.11 g water/g of dry solid) among the four powders. Vacuum spray drying using superheated steam as the heating medium was proven to be an effective way of producing orange juice powders with minimum loss of nutrients.     

Effects of dietary physically effective neutral detergent fiber content on the feeding behavior,digestibility, and growth of 8- to 10-month-old Holstein replacement heifers

The objective of this study was to evaluate the effects of dietary physically effective neutral detergent fiber (peNDF) content on the feeding behavior, digestion, ruminal fermentation parameters, and growth of 8- to 10-mo-old dairy heifers and to predict the adequacy of dietary fiber in growing dairy heifers. Twenty-four Holstein dairy heifers (245 ± 10.8 d of age, 305.6 ± 8.5 kg initial live weight) were randomly divided into 4 treatments with 6 replicates as a completely randomized design. During the 60-d period with a 10-d adaptation, heifers were offered 1 of 4 diets, which were chemically identical but included different peNDF_8.0 (particle size is >8 mm and <19 mm) content (% DM): 10.8, 13.5, 18.0, or 19.8%, which was achieved by chopping forage into different lengths (fine = 1 cm, short = 3 cm, medium = 5 cm, and long = 7 cm). The concentrate and silage were mixed and fed restrictedly and exclusive of forage (Chinese ryegrass hay) were offered ad libitum. The body weight and frame size of the heifers were measured every 15 d during the experimental period. Samples of the rumen content (2 h after the morning feeding) were taken for pH, ammonia, and volatile fatty acid determination. The dry matter intake and average daily gain of the heifers were not significantly affected by peNDF_8.0 content. The body frame size (including withers height, body length, and heart girth) of the heifers was not increased significantly by enhanced peNDF_8.0 content. Ruminal pH and ammonia concentration were both increased with increasing dietary peNDF_8.0 content. The ruminal total volatile fatty acid concentration and percentage of acetate and butyrate profiles were not significantly affected by dietary peNDF_8.0 content. However, the enhanced peNDF_8.0 content led to a decrease in the propionate percentage. The ratio of acetate to propionate in the 13.5% treatment was highest among the treatments. Increasing the particle size and dietary peNDF_8.0 content resulted in increased eating and chewing time but had no effect on rumination time. Heifer total eating and chewing time and eating and chewing time per kilogram of dry matter intake were increased with increasing dietary peNDF_8.0 content. The apparent digestibility of acid detergent fiber and crude protein was improved with an increasing content of dietary peNDF_8.0. The results suggest that an optimal or advisable dietary particle size and peNDF_8.0 content improves chewing activity, rumen fluid pH, and ruminal fermentation. The data based on feeding behavioral and growth responses of heifers as well as rumen fermentation and digestion by improving total eating and chewing time indicate that 18.0% dietary peNDF_8.0 content is the most suitable for 8- to 10-mo-old Holstein heifers.     

Effects of Saccharomyces cerevisiae fermentation products on dairy calves: Performance and health

The aim of the study was to evaluate the effects of Saccharomyces cerevisiae fermentation products (SCFP) on performance and health of calves during the first 63 d of age. Sixty Holstein calves (30 males and 30 females) at 2 d of age were blocked by sex and date of birth then randomly assigned within blocks to 1 of 3 treatments. A texturized calf starter was fed ad libitum containing 0 (control), 0.5, or 1% SCFP (Original XPC, Diamond V, Cedar Rapids, IA) of DM. In addition, the supplemented calves were fed 1 g/d SCFP (SmartCare, Diamond V) in milk until d 30. All calves were fed 4 L of colostrum within 1 h of birth and were subsequently fed milk twice daily until weaned at 56 d of age. Male calves were harvested on d 56. Performance and health of weaned female calves were monitored until 63 d of age to determine the effect of preweaning treatment of SCFP on weaning stress. Starter intake, fecal scores, and medical treatments were recorded daily. Body weight measures and blood samples were collected on d 2, 28, 56, and 63. Serum was analyzed for blood urea nitrogen, fatty acids, insulin-like growth factor-1, glucose, and total protein. Oxidative biomarkers and total antioxidant capacity were also evaluated in the serum. Body weight, DMI, blood parameters, and oxidative biomarkers did not differ among treatments. Supplementation of SCFP lowered fecal scores in the pre- and postweaning periods. Saccharomyces cerevisiae fermentation products can be used to reduce the diarrhea in calves grown under normal commercial conditions.     

Antialcoholic liver activity of whey fermented by Lactobacillus casei isolated from koumiss

Whey fermented liquid (WFL) was studied for its hepatoprotective effects by using chronic alcohol-induced mice. Whey fermented liquid, prepared by inoculating whey with 4% (vol/vol) Lactobacillus casei and then incubating at 41°C for 8 h, was used to orally treat alcohol-induced mice at 3 dosages for 5 wk. Ethanol consumption significantly reduced the activity of superoxide dismutase and glutathione peroxidase, while lowering glutathione content and increasing levels of aspartate aminotransferase, alanine aminotransferase, total triglyceride, malondialdehyde, and cytochrome P450 2E1. Treatment with WFL significantly attenuated the increased levels of alanine aminotransferase, aspartate aminotransferase, triglyceride, and cytochrome P450 2E1, while decreasing superoxide dismutase, glutathione peroxidase, malondialdehyde, and glutathione levels. Pathological changes in the livers of mice who had ingested alcohol were improved by the administration of WFL. These results suggest that WFL may exert a protective effect against alcoholic liver disease by increasing antioxidant activity, which supports the use of WFL as an antialcoholic liver disease treatment.     

Research progress on chemical modification of silk fibroin and its applications北大核心CSCD

Mulberry silk is composed of the two major parts of two triangle-like silk fibroin fibers and sericin covering the fibers and a few lipids. After removing the sericin on the raw silk what is left is the silk fibroin fiber. Silk fibroin is the main part of silk accounting for about 75% of the total weight. Silk fibroin contains 18 natural amino acids such as glycine Gly alanine Ala serine Ser serine aspartic acid Asp and tyrosine Tyr . The secondary structure of silk fibroin has three main conformations α-helix β-fold and random coil. Under certain conditions the three conformations can transform into each other and change the mechanical properties of the silk fibroin material. Silk fibroin extracted from silk fiber is a natural polymer with biocompatibility and biodegradability. It can be further processed into different forms of materials nanoparticles films hydrogels sponges etc. It has been applied in many fields such as biomedicine and cosmetics. In order to meet the needs of different fields researchers have conducted further chemical modification treatment based on the original excellent properties of silk fibroin. Meanwhile the active groups on various amino acid residues in silk fibroin also provide chemical reaction sites for the chemical modification of silk fibroin. The chemical modification methods of silk fibroin mainly include amino acid residue modification macromolecular grafting modification and crosslinking reaction modification. Among them amino acid residue modification can modify protein amino acid residues by chemical reagents and some groups can be introduced into the side chains of silk fibroin macromolecules. Grafting modification of silk fibroin macromolecules is one of the main means to bind functional compounds to silk fibroin macromolecular chains. The properties of grafted silk fibroin are affected by the type and grafting rate of the grafts. The chemical crosslinking reaction modification of silk fibroin macromolecules is to make the macromolecular chains connected by covalent bonds and form a network structure by means of crosslinking agents enzymes or ultraviolet irradiation. The cross-linking reaction can not only form covalent bonds within and between the molecular chains of silk fibroin thus changing its structural properties and improving its stability but be used to form covalent bonds with other polymers. At present the chemical modification of silk fibroin is mainly applied in the fields of silk textiles biomedicine and environmental science. In the field of silk textiles graft copolymerization modification of vinyl and other monomers crosslinking agent modification and other methods are used to overcome the shortcomings of silk like being easy to wrinkle. The graft modified monomers mainly include ethylene methacrylate and methylacrylamide. The active groups on crosslinking agents such as polycarboxylic acid / anhydride and epoxide are covalently combined with carboxyl hydroxyl and amino groups on macromolecules of silk fibroin to improve the wrinkle resistance of silk fabrics. In the field of biomedicine silk fibroin materials with appropriate chemical modification have better biological activity drug delivery ability antimicrobial properties and mechanical properties. The optimization of these properties enables silk fibroin materials to show great potential in drug control delivery tissue regeneration and wound repair. The applied research in the field of environmental science mainly focuses on the adsorption separation and catalysis of impurities in water. Therefore the modification of amino acid residues grafting and cross-linking of protein macromolecules can change some important properties of silk fibroin and meet the requirements of various applications and functionalization of silk fibroin. In many fields of chemical modification and application of silk fibroin protein fruitful results have been achieved which has laid a good foundation for the further development of related fields and also shows that the chemical modification of silk fibroin material has great potential and application prospects. However there are still some problems that need to be overcome and further improved in the current chemical modification methods such as mild modification conditions and accurate adjustment of the degree of modification which will be the research direction of related fields in the future. © 2022 Authors. All rights reserved.     

剑麻/长丝复合绳芯用纱的开发及其性能北大核心CSCD

针对绳芯用剑麻纱生产流程长、毛刺多和强力受限问题,文章在针纺机上设计加装了长丝喂入装置,将剑麻分别与超高相对分子质量聚乙烯长丝、高强涤纶长丝复合,制取了剑麻/长丝复合纱,再经合股和捻绳制取了绳芯。研究结果表明:长丝包覆可减少纱体表面毛刺,并随包覆长丝线密度增加或包覆次数增加而进一步减少;相比传统剑麻绳芯,采用剑麻/PE长丝包芯包覆纱和剑麻/PET长丝包芯包覆纱设计制取的绳芯强力提高了29.8%,含油亦符合标准要求,所制取钢丝绳耐疲劳性能提升50%;复合纱在毛刺减少及所制取绳芯强力提升的同时,无需经由剪毛、烧毛工序,精简了生产流程。