Trans Isomer Content Research Articles

Определение взаимосвязи генотипов SNP с содержанием жирных кислот различной пространственной конфигурации в молоке коров

Abstract. Milk fat is the third main source of lipids for human nutrition. Fatty acids in milk fat have a heterogeneous composition due to differences in chain length, degree of saturation, etc. It has been scientifically proven that long-term consumption of trans-fatty acids causes various diseases of the human body; according to WHO recommendations, their maximum consumption should not exceed 1 % of total energy. A comprehensive study of the composition of fatty acids in cattle milk gives scientists the opportunity to use this trait in breeding work by selecting genotypes with a low content of trans-isomers and saturated fatty acids harmful to human health. The scientific novelty lies in the study of molecular genetic mechanisms for regulating the quantitative content of fatty acids and their trans-isomers in the fat fraction of cow's milk. The purpose of the work is to identify allelic variants of SNPs associated with the fatty acid composition of cow's milk and the content of trans isomers of unsaturated fatty acids in it. Research methods. The studies were carried out on cows of the Holstein black-and-white breed. The genetic profile of animals of the Holstein black-and-white breed was studied, SNPs significantly associated with the quantitative and qualitative content of fatty acids and their trans-isomers in the fat fraction of cow's milk were identified. The fatty acid composition of cows' milk was determined using a multiparameter automatic analyzer MilkoScan 7/Fossomatic 7 FT+ / DC (FOSS, Denmark). Results. Whole-genome genotyping was performed. Analyzing the content of fatty acids with different saturation of hydrogen bonds, a significant difference between the amount of fatty acids and genotypes, reliable values were established only for 5 SNPs. It was found that for four SNPs, the highest values of the content of fatty acids and trans-isomers were in homozygous genotypes ARS-BFGL-NGS-41348GG; BTA-115852-no-rsAA; BTB-00771463GG; Hapmap46159-BTA-70956TT. A significant difference in the content of trans-fatty acid isomers in milk between genotypes was found only for SNP ARS-BFGL-NGS-5502. The largest mass fraction of trans-isomers of unsaturated fatty acids was found in the milk fat of cows with the heterozygous genotype AG, which amounted to 0.076 g/100 g and was 0.011 g/100 g and 0.032 g/100 g (P≤0.01) more compared to heterozygous genotypes GG and AA, respectively.

Hygienic assessment of the consumption of trans fatty acids by the population of the Omsk region

Aim. Assessment of the content of trans-fatty acids in foods consumed by the population of the Omsk region and the values of their actual consumption.Materials and Methods. The results of laboratory studies of food products from the following groups were analyzed: fast food (hamburgers, french fries, chips); confectionery; oils, fats; meat products; dairy products (n=438). In product samples, the mass fraction of trans-fatty acid isomers was determined by gas chromatography. An assessment was made of the actual nutrition and consumption of trans fats by the inhabitants of the region using the method of analyzing the frequency of food consumption (n=441).Results. The median content of trans fats in the main food groups was 0.67% of total fat, which does not exceed the values recommended by WHO. There was a decrease in the content of trans-isomers in food products from 2.7% in the period 2016−2017. up to 1.0% in the period 2020−2021 However, there remains a significant health risk associated with the consumption of trans-fatty acids, due to the high proportion of samples exceeding the recommended levels (24.5±2.1%), to a greater extent the risk was determined by the consumption of confectionery. The median consumption of TFAs in the study population was 1.16 g, which is in line with the recommended norms. The proportion of people with excess recommended consumption was 10.2%.Conclusion. The results indicate an improvement in the situation related to the consumption of trans fats in 2016-2021 due to stricter requirements for their content in food products. It is necessary to conduct further research related to the assessment of the content of trans-isomers of fatty acids in the diet of various population groups to identify risk groups and priority food products - sources of trans fats.

NEW STEREOSELECTIVE CATALYSTS FOR THE HYDROGENATION OF SUNFLOWER OIL

The work is devoted to the creation of new stereoselective catalysts for the hydrogenation of sunflower oil, which can significantly reduce the trans-isomers of fatty acids. Thus, on nickel catalysts used in industry, the content of trans-isomers of fatty acids reaches up to 30%. Platinum deposited on diatomite (processed natural clay) 0.2 to 1% is offered as a catalyst. Methodology. The hydrogenation was carried out in an autoclave, excluding external diffusion inhibition, at hydrogen pressures ranging from 0.25 to 1.0 MPa and temperatures ranging from 90 to 110°C. Results and discussion. Chromatographic analysis was used in all cases to determine the isomeric composition of fatty acids, making it possible for the first time to change hydrogen pressure and reaction temperature without changing the isomeric composition. This allows the study of how stereoisomeric composition changes during the hydrogenation of fatty acids. Various physical methods are used to verify catalysts: TPD, BET, and TEM, etc., which can determine catalyst particle size, hydrogen adsorption forms, and specific surfaces. Conclusion. These characteristics were correlated with the activity and stereoselectivity of the studied catalysts. Trans-fatty acids are found to be two to three times lower on platinum catalysts than on nickel catalysts.

Determination of the fatty acid composition and fatty acids trans-isomers in the horse, stall horse, mutton, beef and pork meat

In this study, we have focussed on the fatty acid composition of the meat of various animals raised in the Republic of Kazakhstan. We have analyzed pasture horse meat, stall horse meat, lamb, beef, and pork meat. Samples from four carcass muscles (back, hip, rib, and neck) were tested. Comparative analysis of the content of trans isomers of fatty acids (TFA) was performed. The analysis of the obtained samples showed that the TFA content is significantly (p <0.05) different in different parts of the carcasses of all animals. Their highest content was observed in the mutton sample, which reached 79.56-82.04%. The beef was next after mutton (6.20-9.64%). Less than in mutton and beef, but more than in pork and TFAs were contained in stall horse meat (2.75-5.52%). Of the two types of horse meat, there was less TFA in horse meat of pasture content (1.85-3.46%). Compared to all studied samples, the lowest level of trans fatty acids was in pork (0.91-1.39%). In horse meat of both types, TFAs were present in trans-9-C16: 1. More types of TFA were found in the meat of other animals: in mutton (trans-9-C14: 1; trans-9-C16: 1; trans-9-C18: 1; trans-11 C18: 1; trans-9-trans- 12-C18: 2), in beef (trans-9-C16: 1; trans-9-C18: 1; trans-11-C18: 1; trans-9-trans-12-C18: 2), in pork (trans-9-C16: 1). In addition to TFA, an analysis was made of the ratio of omega-6 and omega-3 (ω-6: ω-3). Considering that the lower the ratio of ω-6: ω-3 in fat, the healthier it is for the human body, the most optimal among the studied samples in terms of the ratio of ω-6: ω-3 fatty acids was mutton (1.83-2.35) and horse meat of stall keeping (1.76-6.53). The most unfavourable ratios were in the pork samples (17.46-35.69). The ratio ω-6: ω-3 in other animals was within the following limits: beef (5.35-9.13), horse meat of pasture content (7.08-10.50).

Impact of Romanov breed lamb gender on carcass traits and meat quality parameters including biogenic amines and malondialdehyde changes during storage.

The present study aims to evaluate the effect of Romanov breed lamb gender on carcass traits and meat quality parameters, as well as on the formation of biogenic amines (BAs) and malondialdehyde during meat storage. Obtained results revealed that lamb gender had a significant influence on sternum/breastbone, ribs, right shoulder, and bones of the back leg. Significantly higher lightness (by 3%) was found for male meat; however, higher redness of female meat was observed (by 7.7%). In all cases, a lower pH was obtained for female meat. Significantly higher cooking loss (by 38%) was found for male meat. However, gender was not a significant factor in lamb meat proximate composition, or for BAs and cholesterol content. The gender of animals had a significant influence on 10‐heptadecenoic (C17:1), linoleic (C18:2n – 6), total polyunsaturated FA, and total trans isomers content in meat. A significantly higher concentration of malondialdehyde was found in female lamb meat (by 43.4% and 56.8% in fresh and after 3 months of storage at −18°C, respectively) compared to males. Finally, the obtained results supplement the scarce database about the characteristics of Romanov breed meat of different gender and this is beneficial for lamb breeders and meat industry in order to obtain a better quality production.

Chemical Composition, Fatty Acid Profile, and Lipid Quality Indices in Commercial Ripening of Cow Cheeses from Different Seasons.

Simple SummaryCheese and other dairy products are important components of the diet that have a positive effect on human health. These products include substantial amounts of important nutrients, including proteins, bioactive peptides, amino acids, fat, fatty acids, and vitamins. The quantitative composition of fatty acids in milk fat changes under the influence of various factors, such as animal feeding, breed, lactation stage, individual characteristics, climatic conditions, health, age, and others. Of the above-mentioned factors, the most important influence is the diet. This work presents chemical composition and fatty acid profile, with particular emphasis on trans isomers (cis9trans11 C18:2 (CLA), C18:1 and C18:2 isomers) and lipid quality indices in ripening of cow cheeses from different seasons. The first batch contained cheeses produced in winter and purchased from the market between May and June 2020. The second batch contained cheeses produced in summer and purchased from the market between November and December 2020. Results obtained show differences between summer and winter cheeses in their chemical composition, the content of lipid quality indices, and fatty acids.The aim of the study was to compare and demonstrate whether commercial rennet ripening cheeses available on the market in summer and winter differ in their chemical composition, fatty acid profile, content of cis9trans11 C18:2 (CLA) acid and other trans isomers of C18:1 and C18:2 acid and whether they are characterized by different values of lipid quality assessment indices. The experimental material consisted of rennet ripening of cheeses produced from cow’s milk available in the Polish market. The first batch contained cheeses produced in winter and purchased from the market between May and June. The second batch contained cheeses produced in summer and purchased between November and December. Chemical composition was analyzed by FoodScan apparatus. The gas chromatography (GC) method was used to determine the content of fatty acids. Results obtained in the presented study indicate that the chemical composition, content of fatty acids trans isomers, and lipid quality indices varied between summer and winter cheeses. The summer cheeses were richer sources of MUFA and PUFA compared to winter cheeses. Summer cheeses were also characterized by lower content of SFA, higher content n − 3, lower n − 6/n − 3 ratio, and higher content of DFA. Higher contents of CLA and trans C18:1 and C18:2 were found in summer cheeses.

PROCESS METHODS FOR REDUCING (PREVENTING OF THE FORMATION) POTENTIALLY DANGEROUS SUBSTANCES IN THE PRODUCTION OF MEAT PRODUCTS

The article presents the results of research on technological methods that contribute to reducing the content (prevention of formation) of potentially dangerous substances in the production of meat products. The main factors affecting the reduction (prevention of formation) of trans-isomers of fatty acids in the manufacture of products are identified: the use of raw materials with a small content of adipose tissue and vegetable oils (if necessary) with an initially low content of trans-isomers of fatty acids, a decrease in the duration and temperature of heat treatment, modification of the used fats. It has been found that the most effective methods of reducing benzapirene content in the production of meat products are: selection of the type and composition of wood, checking the moisture content of wood, controlling the amount of oxygen, the temperature in the melting zone (at the stage of smoke generation) and the temperature of smoke in the smoking chamber, the duration of smoking, selecting the smoking chamber and equipment of rational construction, filtering or cooling smoke, cleaning smoke from soot between the smoke generator and the smoking chamber, etc. The main factors affecting the reduction (prevention of formation) of nitrosamines in the manufacture of meat products were identified: a decrease in the amount of nitrite salting mixture used (subject to product safety indicators), a decrease in the temperature and duration of heat treatment of products, the manufacture of natural products with short shelf life, the use of ascorbates, ascorbic acid, nicotinic acid, glucose delta lactone (HDL) to inhibit the formation of nitrosamines and to increase the intensity and stability of coloration of finished products, etc.

Ecological approach to the use of secondary products of pea flour and rice grain processing into protein concentrates and phytin

The process of bioconversion of the secondary product of pea flour processing into protein concentrate (serum) into fodder microbial-plant concentrate has been optimized. For this, a composition was selected from the culture of the fungus Geotrichium candidum 977 and the yeast Saccharamyces cerevisiae 121, a mathematical model of concentrate synthesis was developed in the form of an equation that adequately describes the dependence of the biomass yield on technological parameters: pH of the medium, temperature and amount of inoculum. The concentrate from the biomass had a protein mass fraction of 61.68 % of DS, from the biomass with the culture liquid - 57.90 %. Concentrates - biologically complete, the rate of essential amino acids was 107-226 %, out of 30 fatty acids, 97 % were acids that are part of animal fats, vegetable oils or marine organisms. The ratio of saturated and unsaturated acids is 1:3, the content of trans isomers is 5.1 %, omega-6 fatty acids (linoleic) is 19.73 %. The ability of symbiosis between the yeast S. cerevisiae 84/5 and the fungus Trich. cutaneum 656 has been proven. transform the components of whey remaining after the extraction of phytin from rice bran into protein biomass. The ratio of monocultures by mass fraction is 1:1, pH - 5.0…6.0, duration of growth - 72 hours, digestibility – 90 %. The protein is enriched with methionine, isoleucine, leucine, lysine. The amount of essential acids is 18-21 % higher than in concentrates obtained from individual monocultures. The use of concentrates is advisable to use in the diet of animals.

Моніторингові дослідження якості кондитерських жирів та глазурей за жирнокислотним складом

Availability of a wide range of fats and growing production volumes brings to the forefront the issue of reasonable choice of their use in the manufacture of confectionery products and requires quality control of the most common domestic market confectionery fats and glazes. Purpose of the work is to evaluate the quality of the fatty acid composition of fats and glazes manufactured in Ukraine these being in active demand in the food industry for various fillings of confectionery products, candies and chocolate. Subject of study: fatty acid composition and content of trans-isomers of confectionery fats and glazes which are used for the production of confectionery products and affect their nutritional value. Research methods: chromatographic method using gas chromatographs «Cupol-55» and «CrystalLux 4000». Results of the study: it was found that all samples of confectionery fats and glazes differ in fatty acid composition, which is associated with the composition of raw materials and methods of production. In particular, the vast majority of confectionary fats of the non-lauric type contained significantly less saturated acids, about 36-48 %, whereas the lauric type contained 70 %. A distinguishing characteristic was also the amount of monounsaturated acids, which were 25-31 % and 36-46 % for lauric and non-lauric confectionary fats, respectively. The total content of trans-isomers in the analyzed samples of confectionary fat was 0.12-2.88 %. However, elevated trans-C18 : 1 isomer content was shown for 2 of the 11 confectionery glaze samples: in confectionery glaze №155-D – 6,26 %, and in confectionery glaze № 264 – 21,11 %. The confectionary glaze samples are characterized by a more diverse composition of fatty acids at the expense of milk fat, as evidenced by the presence of short-chain acids C4-C10 and other animal fats (presence of conjugated linoleic acid). At the same time, the saturated acid content varied in a wide range from 25 to 47%. The obtained data can be used to produce food products with the predetermined consumer properties.

Food Processing and Effects on Bioactive Constituents: An Opinion Piece

Food processing is an essential unit operation required for production of most food, both industrially and domestically. While, palatability and wholesomeness of food are most important, over processing and inclusion of excessive amount f salt, sugar and solid fat with high content of trans isomers must be avoided. Furthermore, while preservatives and additives are essential for safety of products and shelf-life extension, when and where possible natural products with established safety records should be used. The so-called, ultra-processed food (UPF) that may refer to products that do not follow these criteria are often associated with a myriad of diseases, but again here, caution must be exercised to avoid misuse of terminologies that may create misconception.

Research of oxidation stability of special fats for bread baking industry with minimum content of trans-isomers

Research of oxidation stability of special fats for bread baking industry with minimum content of trans-isomers

CHROMATOGRAPHIC ANALYSIS OF THE EFFECT OF CATALYST QUANTITIES ON THE HYDROGENIZATION PROCESS

Oil and fat industry is one of the important sectors of the food industry. Salomas (Hydrogenated oil) for food and technical purposes are the main components of margarine products, toilet, household soaps, various technological lubricants, cosmetic creams and can be used as valuable chemical raw materials. Objective: ox work is to study the effect of the amount of catalyst on the hydrogenation of cottonseed oil by chromatographic analysis of the resulting salomas. It is confirmed that an increase in the amount of the catalyst from 0.05 to 0.4% percent increases the melting point of salomas and reduces the iodine number, which confirms the known pattern of hydrogenation. Studies on the hydrogenation of cottonseed oil with various amounts of N-820 catalyst have established the possibility of reducing the content of transisomers of fats to 30.1%, increasing the melting point from 28.2 to 43.2 degree C and hardness to 500 g/cm.

Optimizing the parameters of the production process of fat systems with a minimum content of trans-isomers

Optimizing the parameters of the production process of fat systems with a minimum content of trans-isomers

PHOTOCHEMICAL ISOMERIZATION OF OLEFINS

The article is devoted to cis-trans-isomerization of olefins using ultraviolet radiation and narrowly directed UV filters, in the region of which absorption by isomers takes place. It has been proven that irradiation of olefins (hydrogenated fat, fumaric and maleic acids) at high temperatures shows a significant decrease in the content of trans-isomers. When using UV filters with a fixed emission spectrum, the yield of opposite isomers during irradiation (from cis- to trans- and on the contrary) is much higher. The given technology for the isomerization of olefins can be used as a new independent technology for the modification of fats, which will make it possible to obtain a product with an acceptable amount of trans-isomers or will not contain them at all.

Detection of hydrogenated vegetable oils (vanaspati) in ghee using infrared spectroscopy

Infrared spectroscopy, widely used for the characterization of cis- and transisomers of oils and fats, was used for the detection of adulteration in ghee with hydrogenated vegetable oils (Vanaspati) as the latter contains significantly higher levels of trans isomers formed during hydrogenation process used for vanaspati manufacturing. The average content of trans isomers (expressed as % trielaidin) in buffalo ghee, cow ghee and vanaspati as determined using infrared (IR) absorption at 10.36 μ (965.25/cm) was 5.41, 6.82 and 37.05%, respectively. On the basis of increased level of trans isomers in ghee, as low as 5% addition of vanaspati to ghee could be detected easily.

Optimization of the composition of fat systems of new generation

Fats are an integral part of human nutrition. The increased content of trans-isomers in their composition causes a number of cardiovascular diseases and metabolic disorders. A promising approach to solving the problem of minimizing the content of trans- isomers of fatty acid in the composition of food products is the creation of a new generation of fat systems – the oleogel, which is the subject of the presented research. As the dispersion medium of the oleogel, high-oleic sunflower oil is used, in contrast to the oil of traditional varieties, it is possible to obtain systems with enhanced oxidation resistance. The dispersed phase of these fat systems is beeswax, tripalmitin and monoacylglycerols. The choice of a complex of these components is based on their properties to create in oleogels a three-dimensional structure with desired thermomechanical characteristics. At present, there is not enough information about the dependence of the main characteristics of the oleogel on the ratio of ingredients of dispersed phase. In particular, one of the most problematic places in the oleogel technology is its thermal stability, which significantly affects the parameters of production, transportation, as well as storage conditions and periods. To solve this problem, the methodology of the response surface is used in the work. The determination of the unknown values of the parameter vector is carried out by applying regression analysis algorithms. The minimization of the deviation functional is performed by finding the appropriate combinations of experimental predictor series. As a result of research, a mathematical model is developed, which allows, based on data on the component composition of the oleogel, to predict its thermal stability. Reasonably rational mass fractions of the components of the dispersed phase of the oleogel: the content of beeswax is 3.27 wt. %; content of tripalmitin is 3.07 wt. % and the content of monoacylglycerol is 4.70 wt. %, at which the maximum value of the response function is reached. The results will serve as a scientific basis for the development of technological parameters of the industrial production of fat systems of the new generation, the conditions and terms of their storage and transportation.

Высокоэффективные методы модификации жиров для применения в составе молокосодержащих продуктов

The resources of natural solid fats that used in various branches of the food industry are limited. As a result, they are often substituted by chemically and physically modified fats. Until recently, hydrogenation was the main method of modification of fats. Modification allows for products with a high hardness and sufficient resilience to oxidation due to a large amount of trans-isomers. Since the legislation in the sphere of food industry is changing, producers have to look for new solutions for fat-containing products that would correspond with the new restrictions for trans-isomers of fatty acids. The present paper contains a review of modern methods of modified fats production with a reduced content of trans-isomers of fatty acids. It also features some theoretical and practical aspects of multistage fractionation of tropical oils. The authors describe the characteristic of the products of palm oil fractionation and give some recommendations on how various fractions can be applied in milk-containing products. The research included a comparative analysis of various ways of interesterification applied in world practice of jellied fats production. The experiment included interesterification of mixes of the fractioned solid and liquid vegetable oils that can be used in milk-containing products. A specific ratio of raw ingredients in the initial makes it possible to achieve the required technological properties of the final product, as well as to increase its biological efficiency due to linoleic acid. Plastic fats reduce or completely cut the consumption of hydrogenated fats in milk-containing products while increasing their nutrition value, shelf life, and trans-isomeric indicators.

ЗАМІНА ГІДРОГЕНІЗОВАНИХ ЖИРІВ НА РОСЛИННУ ОЛІЮ У СКЛАДІ БОРОШНЯНИХ КОНДИТЕРСЬКИХ ВИРОБІВ

Urgency of the research. One of the trends in the development of the global confectionery market, which is linked to the care of consumers health, is the development of confectionery that do not contain hydrogenated fats. Their source in confectionery are margarines and confectionery fats, which are made on the basis of vegetable oils, in particular, palm and coconut or low-quality animal fats, which are waste meat and fish processing enterprises. A direct relationship between the increased content of trans-isomers in the products and diseases of the cardiovascular system, impaired metabolic processes, in turn, provokes the development of various diseases has been established. Therefore, search for alternative raw materials to replace the hydrogenated fats in the confectionery composition is a need. Target setting. In the process of searching for these types of raw materials, developers are faced with the problem of stabilizing the properties and quality of confectionery containing vegetable oils, namely, the binding and content of oil in dough and finished products. Most often, for this purpose, food additives of a stabilizing action based on high-molecular compounds - polysaccharides and proteins are used. The use of such additives leads to a departure from the traditional formulation of products, adding to the list of ingredients on the packaging of finished products is often in no way understandable to the consumer by E-codes and names. Actual scientific researches and issues analysis. The latest publications have been reviewed, which disclose the mechanisms of negative effects of trans-fatty acids on human health, which also indicate the need to limit the content of trans fats in food products and which suggest alternative sources of fatty materials for confectionery. Uninvestigated parts of general matters defining. Remains relevant search for ways to stabilize the structure of confectionery products, which contain vegetable oil in its composition, without the use of polysaccharides and protein stabilizers. The research objective. The aim of the study is the development of confectionery recipe without the use of hydrogenated fats. The statement of basic materials. Refined sunflower oil as an alternative to hydrogenated fats in the confectionery was used. To stabilize the dough and finished products, as well as to improve their organoleptic characteristics, potassium bitartrate was introduced into the formulation. The physico-chemical and organoleptic properties of finished products manufactured according to the developed recipe were studied. Conclusions. The proposed prescription composition of the confectionery with the use of vegetable oil in its composition allows to obtain finished products with good physico-chemical and organoleptic quality indicators.

Trans Lipid Library: Synthesis of Docosahexaenoic Acid (DHA) Monotrans Isomers and Regioisomer Identification in DHA-Containing Supplements.

Docosahexaenoic acid (DHA) is a semiessential polyunsaturated fatty acid (PUFA) for eukaryotic cells that is found in natural sources such as fish and algal oils and widely used as an ingredient for omega-3 containing foods or supplements. DHA effects are connected to its natural structure with six cis double bonds, but geometrical monotrans isomers can be formed during distillation or deodorization processes, as an unwanted event that alters molecular characteristics and annihilates health benefits. The characterization of the six monotrans DHA regioisomers is an open issue to address for analytical, biological, and nutraceutical applications. Here we report the preparation, separation, and first identification of each isomer by a dual approach consisting of the following: (i) the direct thiyl radical-catalyzed isomerization of cis-DHA methyl ester and (ii) the two-step synthesis from cis-DHA methyl ester via monoepoxides as intermediates, which are separated and identified by nuclear magnetic resonance spectroscopy, followed by elimination for the unequivocal assignment of the double bond position. This monotrans DHA isomer library with NMR and GC analytical characterization was also used to examine the products of thiyl-radical-catalyzed isomerization of a fish oil sample and to evaluate the trans isomer content in omega-3 containing supplements commercially available in Italy and Spain.

Crystalline Nanochannels with Pendant Azobenzene Groups: Steric or Polar Effects on Gas Adsorption and Diffusion?

An azobenzene-containing, zirconium-based metal-organic framework (AzoMOF), upon irradiation with ultraviolet (UV) light at 365 ± 10 nm, underwent trans-to-cis isomerization of its azobenzene pendants to furnish the cis-isomer content of 21% (AzoMOF21%) in 30 min at the photostationary state and underwent backward isomerization into AzoMOF1% upon either irradiation with visible light (420-480 nm) or heating. When the cis-isomer content increased, the diffusion rate and amount of CO2 adsorbed into the nanochannels of AzoMOF decreased considerably. When erythrosine B, a polarity-probing guest, was used, it showed a red shift upon exposure of AzoMOF20%⊃EB to visible light, indicating that the interior environment of AzoMOF turns less polar as the trans-isomer content becomes higher. In sharp contrast, the adsorption profiles of AzoMOF15% and AzoMOF1% for Ar having an analogous kinetic diameter to CO2 but no quadrupole moment and a smaller polarizability were virtually identical to one another. Therefore, it is likely that CO2 experiences a dominant effect of a polar effect rather than a steric effect in the crystalline nanochannels.