Quantitative and Qualitative Evaluation of Chondroitin Sulfate in Dietary Supplements

We propose to evaluate the amount and quality of chondroitin sulfate (CS) from several food supplement preparations in the form of tablets, caplets, or capsules containing CS in varying contents and formulations in the presence of various additives and ingredients, with no other pretreatment than centrifugation to remove insoluble material. To quantify CS, two different analytical approaches were applied after their validation: specific and sensitive agarose-gel electrophoresis and strong-anion exchange–high-performance liquid chromatography (SAX-HPLC) determination of the constituent disaccharides after treatment with specific chondroitin lyases. The CS content in finished products evaluated using the two specific validated methods were found to conform to the label specifications. It is worth mentioning that the quantitative determinations have been performed using a very high pure European Pharmacopeia CS reference standard having substantially the same properties as the food supplement CS samples. Furthermore, by means of the specific agarose-gel elctrophoresis approach, we can exclude the presence in the nutraceuticals of other sulfated polysaccharides produced by extraction from tissues, in particular heparin, heparan sulfate, and dermatan sulfate. The SAX-HPLC separation of unsaturated disaccharides for the nutraceutical CS was also used to evaluate its quality and the possible origin. No disulfated disaccharides typical of CS from cartilaginous fishes, making the charge density lower than 1.0, were found, thus confirming the bovine or porcine origin, the most common sources of this “terrestrial” polysaccharide. Finally, high-performance size-exclusion chromatography (HPSEC) analysis was applied to evaluate the CS molecular mass in food supplements also in the presence of additives and other ingredients. This analytical approach confirmed that the nutraceutical CS samples are of high molecular mass and are not degraded during the food supplement preparations. In conclusion, this multianalytical approach can be used in the direct quantitation and evaluation of the quality and the possible origin of CS contained in food supplement formulations.     

Biotechnology for the conversion of lignocellulosics

During the last three years most of the research on bioconversion of lignocellulosics has focussed on a process scheme where the substrate is first pretreated, usually by high pressure steam, prior to fractionation into its cellulose, hemicellulose and lignin components. The cellulosic rich fraction is then hydrolyzed enzymatically, followed by fermentation of the liberated sugars to ethanol, while the lignin and pentose sugar rich streams are treated separately. The progress in each of these areas is discussed. Round robin activities between the participating labs were used to provide more uniform methods of quantifying cellulase and xylanase enzyme activities. The various technoeconomic models developed by network members were used to identify probable process schemes and determine technical “bottlenecks”. We could also identify which components of the process were the most cost-intensive and determine the levels at which further increases in yields and productivity would have little effect on the cost of the final product.     

Model predictive control of pH in tubular photobioreactors

This paper presents the development and implementation of a branch-and-bound on–off model-based predictive control (MPC) strategy aimed at controlling pH and minimising CO₂ losses in a microalgal tubular photobioreactor. These kinds of photobioreactors are usually controlled by means of an on–off valve and thus classical on–off switching controllers are implemented, without taking into account plant dynamics. In the considered operating range, the nonlinearity of the system is not severe and thus a linear model of the pH evolution in spite of changes in CO₂ injection and in solar radiation has been obtained and used within a MPC framework to achieve desired regulation properties trying to minimise CO₂ losses, as one of the major costs in this installation is the supply of carbon dioxide and its transfer to the culture, amounting to about one-third the cost of the largest scale systems. The paper also shows the results obtained when applying the technique to the real photobioreactor.     

从产业政策看食品及食品添加剂行业的发展前景

作者从我国产业结构、组织、技术和布局政策，分析探索食品添加剂行业今后的发展。     

食品的分光光度分析法进展

食品的分光光度分析法进展方国桢，李志成（四川大学化学系．成都，６１００６４）主题词：食品分析，分光光度法，进展随着人们生活水平和医疗卫生事业的日益发展，人类对食品分析提出了更高要求。近年来关于食品的化学和仪器分析方法报道迅速增多。分光光度法具有简便、...     

Quality of organic coatings for food cans: evaluation techniques and prospects of improvement

A metal container for food packaging must preserve the sensory characteristics of the product for a long-enough shelf-life period. The various problems — technological (insufficient corrosion resistance), hygienic (migration of health-injurious substances into the food product) and ecological — can, in fact, be traced back to the metal container-food product interaction. The paper first presents a general introduction to the basic properties of organic coatings used in the food industry; the different chemical and electrochemical analytical techniques are then examined for their applicability to the study of these properties and to the mechanism of interactions at the lacquered metal /electrolyte interface, leading to information as to the quality of the metal/lacquer system and to its suitability for contact with a specific food product. Experimental data obtained both by investigating actual problems and developing new metal/lacquer couplings are presented. Results of research aimed at studying effects on the coating quality of the mechanical manufacturing and of the chemical nature of a lacquer are discussed.     

The effect of guar gum on microbial activity in the human colon

On feeding a human volunteer a control diet for 21 days, followed by one containing 13·9 g guar/day for a further 21 days, the major changes seen were an increase in faecal output and water content and a decrease in faecal pH and transit time. Faecal output remained high for at least 10 days after return to the control diet. Short chain fatty acid (SCFA) levels/g wet weight of faeces were unchanged during the guar diet but total excretion of SCFA increased because of increased faecal output. Bacterial output was increased although the proportion of guar fermenters remained approximately 20%. Utilization of guar was complete from the beginning of the guar diet, with no period of adaptation. Flatus production substantially increased during the first 10 days of the guar diet but was less noticeable thereafter, suggesting that changes in the pattern of metabolism were taking place in response to continued feeding of guar. Addition of guar to the diet increased α-galactosidase, mannanase and β-mannosidase activity in faeces and most of the activity was associated with the bacterial fraction. In vitro incubation of faecal slurries from the control and guar diets with guar, galactose or mannose showed that SCFA production was lowest and gas production highest when guar was substrate. No effect of diet was seen on utilization of carbohydrate, SCFA and gas production or enzyme activity. Enzyme activity was only induced by guar and was mainly cell-associated.     

Design and testing of solar dryers for processing food wastes

This paper investigates the potential of using two solar dryers manufactured from locally available materials under Jordanian climatic conditions for drying food wastes for utilization as animal feed. The first dryer is a radiative–convective type while the second is a solar boiler dryer. Tests were also conducted to investigate the nutritious values of the dried products and their suitability as animal feed. It was found from tests that the solar boiler dryer is more efficient than the radiative–convective dryer for producing animal feed in terms of both quality and quantity. The nutritious values of the end products from the dryers were found to be within the international recommended values used for feeding chickens.     

Micromechanical compartments for biotechnological applications: fabrication and investigation of liquid evaporation

Arrays of microcompartments for combinatorial chemistry and biotechnological applications have been fabricated by means of photolithography and anisotropic chemical wet etching. Integration levels of 25 000 per 4″ wafer have been achieved. Optically transparent membranes or microsieves allowing for rinsing between process steps can be incorporated. The liquid evaporation from the microcompartments has been investigated using compartments of different shape. The evaporation rate can be reduced by a factor of by using properly designed microcompartments with small openings. For the investigation of thermally biochemical reactions a microcompartment array with integrated thermo control has been developed, which allows the adjustment of thermal gradients over a 4″ wafer. Peak temperatures exceeding 90°C at the centre of the wafer as well as temperature gradients with ΔT=30°C can be demonstrated.     

Plant biotechnology and food crop development in Sub-Saharan Africa

Biotechnology represents the newest challenge in the ongoing scientific progress in this millennium. Indeed what were seen as promising technologies a few years ago have already produced results; new crop varieties, animal species and agricultural processes. In crop improvement, for example, biotechnology has produced a wide range of applications including micro-propagation of crop varieties for commercial purposes, somatic embryogenesis, inter-specific crosses, gene transfers, and disease control and haploid production. Although modest in comparison with the prospects originally envisaged, mankind cannot but acknowledge these achievements, the regulatory control and commercial exploitation of biotechnology on standards of living of the human society.