Characteristics of protein digestion in artificial feeding in an experiment

It has been established that during artificial feeding with milk substitute containing different protein components (casecite, bovine serum albumin, fibrinogen), the proximal-distal gradient of cavitary digestion of proteins is observed, with this gradient being more demonstrable as compared with natural feeding of postnatal animals. It has been shown that during experimental natural feeding, the proximal-distant gradient is observed in the distribution of acid proteinases in the small bowel, whereas during artificial feeding one can see a uniform distribution of acid proteinases in the proximal and distal parts of the small bowel. The activity of acid proteinases in the gastric mucosa of 18-day-old animals kept on natural feeding does not differ from the activity of these proteinases under artificial feeding with a substitute containing casecite as protein component. Artificial feeding with a substitute containing bovine serum albumin and fibrinogen as protein component entails a decrease in the activity of acid proteinases in the gastric mucosa.     

Net absorption and ruminal concentrations of metabolites in nonpregnant dry Holstein cows before and after intraruminal acetic acid infusion

Objectives were to define daily patterns of net absorption of various nutrients and to assess effects of intraruminal infusion of acetic acid on concentrations of ruminal fluid and net absorption of various metabolites. These characteristics were measured in three nonpregnant, dry Holstein cows (491 kg) at hourly intervals for 24 h before and after 5 days of intraruminal infusion of acetic acid to provide energy equal to 10% of daily intake of metabolizable energy. Cows were fed a completely mixed, 60% corn silage, 40% grain supplement diet at maintenance intake; daily rations were split into two feedings. Net rates of absorption were greatest after feeding and least during early morning. Net absorption of all metabolites measured was similar for the two daily feeding intervals, indicating daily net absorption could be calculated from either feeding interval. Intraruminal infusion of acetic acid caused increased ruminal and plasma concentrations of acetate, increased net absorption of acetate, and almost a twofold increased loss of urea-nitrogen from plasma to the gut. Sixty-nine percent of acetic acid infused was accounted for by increased net absorption of acetate. Ruminal fluid concentrations and net absorption of other volatile fatty acids were not affected by infusion of acetic acid. Net absorptions of ammonia-nitrogen, L-lactate, and glucose likewise were not affected. Net absorption of volatile fatty acid and L-lactate was 43% of daily intake of metabolizable energy.     

The pre- and postoperative nutritive maintenance of rats with enterostomata

The repercussion of nutrition on the food behaviour, bowel function and body mass development of rats with ileostomata and colostomata has been studied during the perioperative phase. An and libitum feeding until immediately before the operation has been found to be beneficial. The postoperative dietetic regimen is of decisive importance to the survival of the animals operated on. The best postoperative development was achieved in ileostomized rats by a diet rich in nutrients and energy, and low n bulkage. In rats with colostomata, the success of the operation may be impaired by a constipation in the intestinal region before the stoma, which frequently leads to occlusion. A spontaneous evacuation of chyme was induced in these animals only by a high-lactose and low-protein diet. It is recommended to keep the experimental animals on pre- and postoperative diets which take into account the location of the respective enterostoma.     

Lactose--a potential dietary fiber. The regulation of its microecological effect in the intestinal tract. 1. Problems, state of knowledge and methods]

Food components of different chemical structure which attain the colon without being attacked by digestion and absorption during their transit through the small intestine are defined as dietary fibre. In the colon they serve as energy or nutrient source for the intestinal microflora or are excreted without change. Not only chemical structure is decisive when a food component has to be assigned to either nutrients or dietary fibre: Substances resisting small intestine digestion due to the lack of corresponding catabolizing enzymes in man are supposed to be "obligate" dietary fibre. "Potential" dietary fibre are nutrients which are only partially digested in the small intestine. Lactose--the main carbohydrate of milk--represents a typical potential dietary fibre. The present paper investigates the factors being responsible for both the degree of lactose utilization in the small intestine and its efficiency in the colon.     

Bioavailability of vitamins

In recent years, there has been a reduction in caloric intake in populations with decreased energy demands. This has place a greater emphasis on the bioavailability of nutrients in foods because the total intake of nutrients is generally closely linked with total caloric intake. An assessment of the adequacy of dietary intakes of nutrients requires not only knowledge of the nutrient content of the foods ingested but also the extent to which the nutrient present in the diet is available for absorption and utilization. Nutrients ingested but not released during the digestive process for absorption are of no nutritional value. Bioavailability may be considered the relative absorption of a nutrient from the diet. An index of bioavailability may be extended to include the relative accumulation of a nutrient into various tissues. Various nutrients and dietary components interfere with the bioavailability of vitamins. Hence, requirements for vitamins cannot be considered independently, but must be evaluated in relationship to other nutrients and compounds consumed by an individual. An overview has been presented as to the factors that influence the bioavailability of vitamins in the human food supply.     

Effect of raw and heat–moisture‐treated high‐amylose corn starches on the process of digestion in the rat digestive tract

High‐amylose corn starch (HAS) is widely known as a resistant starch foodstuff. We developed heat–moisture‐treated high‐amylose corn starch (HMT‐HAS) that was more resistant to enzymatic hydrolysis. Resistant starch contents of HAS and HMT‐HAS using the enzymatic–gravimetric method were found to be 30% and 65% respectively. Rats were given 10% ordinary corn starch (CS), HAS or HMT‐HAS by meal feeding for 10 days. The caecum contents increased and the caecal pH was lower after their diets were supplemented with HAS and HMT‐HAS. Starch contents increased in the upper and the lower small intestine with HAS and HMT‐HAS. Caecal starch with HAS and HMT‐HAS was more than that with CS. Particularly, caecal starch with HMT‐HAS was seven times more than that with HAS. There were no differences in starch content in the large bowel between CS and HAS, but the content increased with HMT‐HAS. These results suggested that HAS and HMT‐HAS were resistant to digestion and absorption in the small intestine, and any indigestible starches reached the caecum. In the caecum, HAS was hydrolysed almost completely by intestinal bacteria; however, some HMT‐HAS escaped bacterial hydrolysis. This escaped HMT‐HAS reached the large bowel and was excreted in the faeces. © 1999 Society of Chemical Industry     

Penetration of Escherichia coli O157:H7 into lettuce as influenced by modified atmosphere and temperature.

The effects of temperature and atmospheric oxygen concentration on the respiration rate of iceberg lettuce and Escherichia coli O157:H7 cells attachment to and penetration into damaged lettuce tissues were evaluated. Respiration rate of lettuce decreased as the temperature was reduced from 37 to 10 degrees C. Reducing the temperature further to 4 degrees C did not affect the respiration rate of lettuce. Respiration rate was also reduced by lowering the atmospheric oxygen concentration. Lettuce was submerged in E. coli O157:H7 inoculum at 4, 10, 22, or 37 degrees C under 21 or 2.7% oxygen. Attachment and penetration of E. coli O157:H7 were not related to the respiration rate. The greatest numbers of E. coli O157:H7 cells attached to damaged lettuce tissues at 22 degrees C at both oxygen concentrations. More cells were attached under 21% oxygen than under 2.7% oxygen at each temperature, but this difference was small. Penetration of E. coli O157:H7 into lettuce tissue was determined by immunostaining with a fluorescein isothiocyanate-labeled antibody. Under 21% oxygen, E. coli O157:H7 cells showed greatest penetration when lettuce was held at 4 degrees C, compared to 10, 22. or 37 degrees C, and were detected at an average of 101 microm below the surfaces of cut tissues. However, under 2.7% oxygen, there were no differences in degree of penetration among four incubation temperatures. The degree of E. coli O157:H7 penetration into lettuce tissue at 4 or 22 degrees C was greater under 21% oxygen than under 2.7% oxygen; however, no difference was observed at 37 degrees C. Conditions that promote pathogen penetration into tissue could decrease the effectiveness of decontamination treatments.     

Effects of macronutrients on mineral distribution in cashew (Anacardium occidentale L)

The effects of macronutrients on nutrient absorption and distribution in cashew have been investigated in sand culture. The absorption and distribution of nutrients were appreciably affected by macronutrients. The type of the relationship between any two of the nutrients in most cases depended on the plant part considered and the ratio of the concentrations of such nutrients in the nutrient solution. Contrary to the generally accepted views of cation antagonisms, it was found that the relationships among cations were synergistic under certain conditions. In general, it seems that low to moderate doses of any of the macronutrients may be beneficial to cashew in masking the deficiency of one or more of the other nutrients.     

燕麦膳食纤维对胃肠道功能影响

除降低血脂和影响血糖反应外,燕麦膳食纤维还表现出其它生理功能,如影响肠道排空,减少营养素吸收,餐后延长饱腹感等;在大肠中,燕麦膳食纤维具有发酵能力,能产生短链脂肪酸,促进一些有益菌生长和增殖,该文综述以上几方面进展。     

The effect of a raffinose diet and cooked legumes on various processes in the large bowel in the rat

Changes of pH, enzyme activity and microflora in the large bowel of the rat after feeding them various diets containing raffinose and leguminous seeds (soybean, peas and beans) have been studied. Feeding a 12% raffinose-containing diet as well as cooked leguminous seeds lowered pH. However, similar decrease of pH was observed after some other diets (for example, milk powder or raw pearl barley). Remarkable alpha-galactosidase activity in the large bowel of rats after legume diet has been observed whereas it was not noted in the small bowel. The source of alpha-galactosidase are probably bacteria of the large intestine content (Lactobacillus spp., Enterococcus, Escherichia coli). No relationship between the isolated microflora and kind of a diet was observed.     

油墨在胶版纸中的渗透深度研究

为了研究纸张的动态吸收性与油墨的渗透深度之间的关系,预测油墨在胶版纸中的渗透性深度,选用10种胶版纸,采用HVL-PDA动态渗透分析仪,以水为测试液体,测量了10种胶版纸的动态吸收特性。同时,采用印刷适性仪对这10种胶版纸进行胶印打样,并用三维视频显微系统VHX-600对油墨的渗透深度进行测量,结果表明,胶版纸动态吸收特性对油墨的渗透深度有一定的影响。     

解决压丸机喷体滑板对软胶囊装量稳定的影响

目的 对压丸机喷体滑板进行改造, 解决软胶囊开机过程中产品装量差异大的问题, 提升开机效率, 稳定产品质量。方法 喷体在注料状态下滑板和底座间的注料孔错位, 在外气缸与滑板处加装2.5 mm厚的垫圈, 使滑板整体往外拉2.5 mm, 把垫圈与设备部件加工成一个整体, 避免由人员安装误差造成的差异。结果 通过改造, 使注料孔通过率由原来的40%提升到100%, 开机调试时间由原来的平均3 h降为0.5 h, 产品装量差异由原来的±20 mg降为±5 mg。结论 改造后压丸机更适合软胶囊产品的生产, 产品质量更加稳定, 开机效率更高。     

Dissolution tests as a tool for predicting bioaccessibility of nutrients during digestion

Bioaccessibility and bioavailability of active ingredients (like vitamins, antioxidants, etc.) into food systems is often compromised by factors like low permeability and/or solubility within the gut, lack of stability during food processing (temperature and oxygen) as well as in the gastrointestinal tract (pH, enzymes, presence of other nutrients). Moreover, little is known on the influence of food structure and breakdown in the gut on nutrient release. The possibility of predicting the release of nutrients from food matrices under simulated gastrointestinal conditions is of great relevance in order to define which food matrix is best for which nutrient, as well as for looking at the interaction of ingredients with the enzymes involved in the digestive process. This study explores the potential relevance of dissolution tests as a tool for predicting bioaccessibility of nutrients during in vitro digestion. Whey protein hydrogels containing green tea extract (GTE) were chosen for this study. Different simulated in vitro gastrointestinal conditions (GI) were applied throughout the dissolution experiments and the GTE was analysed by UV–vis absorption spectroscopy. It was possible to distinguish between two different release kinetics when experiments were performed in simulated gastric or intestinal media. In the gastric step, the kinetic of GTE release was lower than in an intestinal environment, suggesting that more GTE is released and available for absorption into the intestine than in the stomach. The present study shows that it is possible to use the dissolution tester as a screening method to mimic nutrient release from a food matrix in the gastrointestinal tract.     

胶原蛋白在运动食品中的应用及其对运动员的影响

众所周知,运动员在运动过程中会极大消耗体能,但运动员摄入特殊的营养素,可以发挥他们的最大运动能力。近年来运动营养研究发现,胶原蛋白因具有高吸收利用率、提高免疫、锁住钙质、补充水分等特性而被格外关注。本文首先介绍了胶原蛋白的结构特点,对胶原蛋白的生物学功能加以概述,重点探讨了胶原蛋白对运动员的影响及在在运动食品领域的应用,从而为胶原蛋白功能产品的研究和开发提供理论参考。     

Parametric study of a yellow birch surface impregnation process

Wood is a renewable resource that has been used as a material in appearance products for years. Despite its acceptable mechanical resistance, different modification processes were developed to enhance wood’s hardness and make it an even more durable material. Impregnating wood pores with monomers under vacuum-pressure cycle is a common method for that purpose. However, most implemented processes are long and mostly submerge wood into a monomer formulation (Bethell’s full-cell process). For that, they can be considered wasteful on the quantity of materials used, energy consumed and on process duration. The objective of this paper was to evaluate the parameters that influence the penetration of monomers into the tangential surface of Yellow birch (Betula alleghaniensis Brit.) samples. The analyzed factors were the monomer formulation’s viscosity, the surface temperature, the vacuum level applied to the process, the anatomy of samples, and the absorption time. After impregnation, the weight gain of the samples was calculated. Monomer penetration depth was calculated and visualized using density profiles and micro X-ray tomography imaging. Results showed that using a low viscosity monomer formulation allied to a certain level of vacuum and absorption time can considerably increase the impregnation into the wood.

     

Effect of seed lectins from Phaseolus vulgaris on the development of larvae of Callosobruchus maculatus; mechanism of toxicity

Seeds of the kidney bean (Phaseolus vulgaris) are toxic to developing larvae of the bruchid beetle (Callosobruchus maculatus), a major storage pest of many legumes. Insect feeding trials were carried out whereby the albumin and globulin protein fractions from seeds of P. vulgaris were incorporated into artificial seeds. Both fractions were shown to be toxic and to contain haemagglutinating activity, implicating the seed lectins as being involved in seed resistance. Further feeding trials using different P. vulgaris lectin preparations confirmed the toxicity of these lectins and suggested that it was the E-type lectin subunits (erythrocyte-binding) which were the major antimetabolites. Indirect immunofluorescence investigations using monospecific antisera for globulin lectins showed that the lectins, when ingested by the larvae, bound to the midgut epithelial cells. It was suggested that the mechanism of lectin toxicity in this instance is analogous to that known to occur in the rat, namely that the ingested lectin causes disruption of the epithelial cells of the larval midgut leading to breakdown of the transport of nutrients into these cells, and the absorption of potentially harmful substances. This is the first time that evidence for the mechanism of lectin toxicity has been obtained in insects.     

Potential for using a protein-based enteral feeding formula as nutrient mixtures in transintestinal nutrition

Chronic experiments on semi-fistula dogs with temporal-isolated parts of the small bowel were made to study the rate of nitrogen, glucose, lipid, sodium, potassium, calcium and water absorption from protein enteral nutrition and nutritive mixtures prepared on its basis. It was established that a nutritive mixture based on 10% protein enteral nutrition with additives in the form of fatty emulsion and sodium chloride was quite suitable for transintestinal administration. The increase of the concentration of protein enteral nutrition administered transintestinally or its preliminary hydrolysis by gastric juice resulted in the enhancement of evacuatory function of the small bowel.     

Effect of casein phosphopeptides on bioavailability of the alimentary minerals

Caseinophosphopeptides (CPPs) are phosphorylated casein-derived peptides which possess the ability to bind and solubilise minerals, such as Ca2+. The high bioavailability of Ca2+ fram milk and dairy products has been attributed to the production of CPPs which are produced following digestion of casein by the action of gastrointestinal proteinases. CPPs, which appear to be resistant to extensive proteolytic degradation, accumulate in the distal small intestine where they are purported to play a role in enhancing the passive absorption of Ca2+ and other trace elements. A recent human feeding tral reported improved Ca2+ and Zn2+ absorption following CPPs incorporation into food. This review summarises the production, characterization and potential applications of CPPs.     

异辛醇聚氧乙烯醚磷酸酯的合成与应用

 研究五氧化磷的投料方式、反应物的用量比、反应温度和反应时间等因素对合成的异辛醇聚氧乙烯醚(C8H17 (EO) 4OH) 磷酸酯性能的影响,得到优化的异辛醇聚氧乙烯醚磷酸酯的合成工艺条件:在强烈搅拌下,分批投入P2O5 ,加料时的温度不超过45 ℃, n (C8H17 (EO) 4OH) ∶n (P2O5 ) = 2∶1 ,酯化温度为70 ℃,酯化时间为4 h ,在温度70 ℃时加入定量的水再水解2 h。实验结果表明按优化工艺条件合成的异辛醇聚氧乙烯醚磷酸酯在质量浓度为200 gPL的强烧碱溶液中的渗透时间为4 s ,具有良好的耐强碱渗透能力。     

Mass Transfer and Nutrient Absorption in a Simulated Model of Small Intestine

Abstract: There is an increasing need to understand how food formulations behave in vivo from both food and pharma industries. A number of models have been proposed for the stomach, but few are available for the other parts of the gastrointestinal tract. An experimental rig that simulates the segmentation motion occurring in the small intestine has been developed. The objective of developing such an experimental apparatus was to study mass transport phenomena occurring in the lumen and their potential effect on the concentration of species available for absorption. When segmentation motion was applied the mass transfer coefficient in the lumen side was increased up to a factor of 7. The viscosity of the lumen, as influenced by guar gum concentration, had a profound effect on the mass transfer coefficient. The experimental model was also used to demonstrate that glucose available for absorption, resulting from starch hydrolysis, can be significantly reduced by altering the lumen viscosity. Results suggest that absorption of nutrients could be controlled by mass transfer. Practical Application: To address health-related diseases such as obesity, novel foods that provide advanced functions are required. To achieve the full potential offered by the latest developments in the field of food material science, a fundamental understanding of the behavior of food structures in vivo is required. Using the developed gut model we have demonstrated that absorption of nutrients can be controlled by mass transfer limitations.