Study on the structure and properties of modified silk with ultraviolet absorbent北大核心CSCD

The silk fiber has an irreplaceable position in textile fibers and related silk fabrics have the advantages of light and airy texture good moisture absorption and breathability comfort in wear etc. It is also widely used in other fields such as the biomedical sector. However silk also has its own limitations poor light resistance and susceptibility to ultraviolet light especially the ultraviolet light of 290-400 nm wavelength in daylight such as under which condition it is prone to yellowing and photodegradation. The yellowing of silk is due to the photo-oxidation of tyrosine and tryptophan in silk protein under the action of ultraviolet light from sunlight and due to the production of yellow substances which affects the whiteness of silk. In addition from the molecular structure of silk most of the amino acids susceptible to UV light are distributed in the amorphous region. As the amorphous region is affected the structure of the crystalline region is also gradually relaxed the local degradation begins and the silk protein macromolecule chain is cleaved which leads to the decrease of the mechanical properties of silk fibers and accelerates the aging of silk fibers and fabrics. Therefore it is necessary to modify the silk products outside the anti-purple line. The current methods used to modify silk are mostly for post finishing modification including coating impregnation and chemical grafting methods but these methods often affect the original color or feel of the fabric and the durability of the modified effect is also poor. The feeding method is a green method to obtain modified silk by spraying mulberry leaves or artificial feed mixed with modifier which is ingested by silkworm and transferred to silk gland. In this study five aminobenzene UV absorbers were used as exogenous additive food for silkworms. The effect of molecular polarity on the transport of modifiers to silk glands was investigated and their effects on silkworm development and silk structural properties were studied. It was found that the aminobenzene UV absorbers were more easily transferred to the central silk gland silk glue and less to the posterior silk gland (fibroin). 4-dimethylaminobenzoic acid was found to be the highest in the posterior silk gland with a content of 3. 27 μg / strip. The cocoon width and cocoon quality of this group were significantly lower than those of the control group and the silk gum content was increased when this group was used as the study object. Compared with the control group the relative content of β-folded structure and crystallinity of the silk in the addition feeding group decreased slightly. The silkworm silk in the feeding group showed a certain UV absorption ability. After 330 h UV irradiation the breaking strength and elongation of the control group decreased by 48. 95% and 43. 52% respectively while those of the feeding group decreased by 42. 03% and 34. 18% respectively. In this paper UV absorbers were added to silkworms to obtain modified silk mainly focusing on the transfer of the modifier to the silk gland and the structural properties of the modified silk only for the most UV absorbers to enter the silk gland of the posterior group of silk. Other properties of the modified silk such as washing resistance have not been studied and some more in-depth studies are required. For instance it needs to be studied in depth for the limited absorption of exogenous additives by silkworms additive food's being not always absorbed by silkworms and transferred to the silk gland and the mechanism of action between the additive food and silk protein after the former's entering the silk gland. © 2022 Authors. All rights reserved.     

Preparation and characteristics of bombyx mori sericin / tussah silk fibroin / gelatin-based blended antibacterial films北大核心CSCD

A large number of wound dressings are currently used in the treatment of burns chronic ulcers etc. An ideal wound dressing should prevent dehydration of the wound and retain a favorable moist environment at the wound interface. It should have good antibacterial properties and be easily removed without trauma too. Wound dressings are generally made of readily available bio-materials that require minimal processing possess nontoxic non-allergenic and antimicrobial properties as well as promote wound healing. Clinically collagen chitin chitosan etc. are usually used as materials for producing wound dressings as these materials are capable of accelerating the healing processes at molecular cellular and individual levels. Tussah silk fibroin bombyx mori sericin and gelatin non-toxic and extensive have good bio-compatibility degradability and film-forming properties which are conducive to cell adhesion. In order to prepare safe biofilms with excellent antibacterial properties we prepared a kind of bombyx mori sericin / tussah silk fibroin / gelatin BS-TSF-GEL blended film by using tussah silk fibroin bombyx mori sericin and gelatin as bio-based materials and polyethylene glycol 200 as the cross-linking agent. Firstly we designed the single factor experiment and orthogonal experiment to optimize the preparation process of the BS-TF-GEL blended film. On this basis the blended film was modified with ethanol of different concentrations to improve its strength and crystallinity. The structure and properties of the blended film were characterized by measuring the dissolution loss rate tensile properties microscopic morphology and crystal structure. Finally antimicrobial peptides were loaded by adsorption to obtain the BS-TSF-GEL antimicrobial film. The results showed that the ratio of the optimum formula for the (BS-TSF-GEL) blended film required a mixture of bombyx mori sericin (4. 50 μg / mL) and tussah silk fibroin (27. 5 mg / mL) with a volume ratio of 2:1 polyethylene glycol 200 and gelatin solution (360 mg / mL) which accounted for 35% 40% and 25% respectively of the total system. The dissolution loss rate of the BS-TSF-GEL blended film was 34. 62% the elongation at break was 34. 15% and the breaking strength was 578. 8 kPa after being treated with anhydrous ethanol. FTIR and X-ray diffraction results showed that Silk Ⅱ dominated the BS-TSF-GEL blended film while Silk Ⅰ was in a small amount. The BS-TSF-GEL blended film was pale yellow and porous on the surface which was the ideal material for loading antimicrobial peptides. The BS-TSF-GEL blended film loaded with antimicrobial peptides had a good inhibitory effect on both Escherichia coli and Staphylococcus aureus. It is expected to be used in the field of disposable biomedical materials such as wound dressings. In this study three natural materials with unique advantages were selected as substrates for biofilms and polyethylene glycol with high bio-safety was used as the cross-linking agent to enhance the application value of the blended film by loading antimicrobial peptides. The results broaden the application field of silkworm silk and provide a new way for the development and exploitation of silk fibroin in biological dressings and other medical bio-materials. Bombyx mori sericin tussah silk fibroin and gelatin have been widely used in biological tissue engineering as natural biological materials. In this study three natural materials were used as the biofilm substrate to successfully prepare excellent-performance BS-TSF-GEL blend film using polyethylene glycol cross-linking and ethanol post-treatment techniques. Moreover specific properties can be conferred by replacing different loading substances such as antimicrobial biofilm carrying antimicrobial peptides and biofilm sustained release carrier loading drugs. In addition 3D printing electrostatic spinning and other technologies can also be used to shape the BS-TSF-GEL into different shapes to meet the application requirements under different conditions. In conclusion the research results explore a new way for the application of silk protein. © 2022 Authors. All rights reserved.     

Effect of low-molecular-weight silk fibroin peptides on cell growth property北大核心CSCD

The main purpose of this paper is to analyze the effects of low-molecular-weight silk fibroin peptides (LMW-SF) on cell growth characteristics. Firstly, LMW-SF was achieved from silk fibroin enzymolysis by neutral protease. Secondly, LMW-SF was sterilized by filtration and high-pressure steam, respectively. Finally, the effects of LMW-SF on the growth of human normal liver cell (L02) and human liver cancer cell (HepG2) were tested under the volume concentration of 0. 1 ∼5.0 mg/mL, and the relative growth rate (RGR) was calculated. The results show that LMW-SF have slight effect on cell growth at low concentration (0. 1 mg/mL and 0. 5 mg/mL); when the volume concentration is high (2. 5 mg/mL and 5. 0 mg/mL), the lowest value of RGR is 8. 3%, indicating a strong inhibition effect on cell growth. RGR is up to 227. 4% after high-pressure steam sterilization, showing a strong promotion effect on cell growth. It is obvious that LMW-SF have a strong effect on promoting cell growth after highpressure steam sterilization, and high-pressure steam sterilization could be a necessary process when protein is applied in tissue engineering scaffolds. © 2017 China Silk Association. All rights reserved.     

Biomass-derived Porous Carbon Materials for Supercapacitor Electrodes: A Review

The development of renewable,cost-efficient,and environmentally friendly electrode materials with excellent performance is urgently needed for improving supercapacitors(SCs).Recently,biomass-derived porous carbons(BPCs)have received increasing attention due to their excellent physical and chemical properties,widespread availability,and low production cost.In this review,the progress in preparing BPCs and the properties of prepared BPCs are presented and discussed.In addition,the applications of BPCs as electrode materials for supercapacitors are also summarized.More importantly,the pore structure and surface properties of BPCs are all determining factors to improve electrochemical performance.Moreover,a high energy density and power density can be pursued by using composites based on BPCs as electrode materials,of which combining transition metallic oxide with BPCs is one of the most attractive selections.Therefore,rational design of BPCs with respect to the supercapacitor's performance should be conducted in the future.     

Pore Structure Regulation of Carboxyethylated Microfibrillated Cellulose Films

Carboxyethylation is a recent chemical pretreatment for preparation of microfibrillated cellulose(MFC).The carboxyethylated MFC film prepared by coating method has compact structure and high mechanical properties.In order to expand its application,three approaches including using organic solvents,different drying methods and cationic additives,have been adopted in this paper to enrich and regulate the pore structure of MFC film.The results show that all the approaches can improve the pore structure but decrease the mechanical properties of MFC film.When organic solvents such as ethanol,isopropanol and n-butanol were used to replace the water in MFC suspension or pre-dried MFC film,the pore structure of films were increased.Additionally,the film obtained by freeze-drying or air-drying after freezing in liquid nitrogen or freezer has high porosity but poor strength.The best drying process is to rewet dry MFC film,freeze in liquid nitrogen and then freeze-dry.Moreover,the addition of cationic polyelectrolytes or alkene ketone dimer(AKD)in MFC suspension can also significantly increase the film's porosity.Through the above approaches,the porosity of carboxyethylated MFC film can be regulated between 20% and 90%.     

Green and Effective Ammonium Carbonate-assisted Process for Drying Hemicellulose Obtained through Alkali Extraction of Bleached Bamboo Kraft Pulp

Hemicellulose has a wide range of applications,including that as an emulsifier for the food industry and raw material for the synthesis of bioethanol/biochemicals and biodegradable films.Hemicellulose is usually present as a spent liquor,such as the prehydrolysis liquor of the prehydrolysis kraft dissolving pulp production process and the alkali extraction liquor of the cold caustic extraction of pulp fibers.Due to its dilute nature,hemicellulose needs to be dried for practical utilization,and this is challenging.In this study,cellulose and hemicellulose in a bleached bamboo kraft pulp were separated using an alkali extraction process.Hemicellulose obtained from the extraction liquor was dried by an ammonium carbonate-assisted drying process.The effects of drying time and drying temperature were determined.Structure of the hemicellulose obtained by the ammonium carbonate-assisted drying process was similar to that of original hemicellulose,as revealed by detailed Fourier transform infrared and X-ray diffraction analyses.The novel drying method was more energy efficient and required a shorter drying time than the conventional freeze drying method,and the excellent solubility in alkaline solutions favored the chemical modification of hemicellulose.The dried hemicellulose can be used as a renewable raw material for the preparation of hydrogels and other substances such as bioethanol/biochemicals and biodegradable films.     

Preparation of Highly Crystalline Microcrystalline Cellulose by Hydrolysis of Cellulose with Phosphotungstic Acid

Phosphotungstic acid(H_3PW_(12)O_(40), HPW), a kind of solid acid, is widely used for hydrolyzing cellulose to prepare microcrystalline cellulose(MCC). MCC is usually used in food, synthetic leather, chemical and pharmaceutical industries. The use of response surface methodology(RSM)can help avoid the random error caused by single factor experimental design,reduce test times and cost, and improve quality. The RSM was used in this study to determine the following optimal process conditions: H~+ molar quantity, 31 mmol/L; reaction temperature, 93℃; reaction time, 2 h; and solid to liquid ratio, 1∶38. Under these conditions, the crystallinity of MCC was77.4%. Thus, the use of RSM allows the preparation of MCC with higher performance and increased crystallinity.     

腌肉制品中的亚硝酸盐与亚硝酸盐替代物(英文)

Nitrite is a reactive chemical and regarded as one of the most important curing agents in meat products.However,from a food safety perspective,nitrite is responsible for chemical toxicity and N-nitrosamine formation.Investigations on the reactions of nitrite in cured meat products have been carried out in many countries.In this paper,the reactions of nitrite in meat and potential problems currently associated with cured meat added nitrite were reviewed.This article summarized the factors that can influence the residual nitrite in cured meats.These factors would result in changes of nitrite contents for the processing and subsequent storage.Many countries have made efforts to restrict the amounts of ingoing and residual nitrite by law.The potential substitutes for nitrite in cured meat products and the development of uncured nitrite-free meat system were also described here.     

POSTSCRIPT

Rapeseed is one of the most important oil seed in the world, and it is a valuable source of high quality protein as well as edible oil. Its protein comprise 35～45% of the meal that remains after extraction of the oil. The balance and availability of its amino acids are comparable with those of soya bean meal and if it is fortified with methionine and arginine, it can satisfy the entire requirement of the chicken. However, as containing some of the toxic substances or anti-nutritional factors such as fibre, phenolics, phytic acid and glucosinolates, it has deleterious effects on per-formance and health of the poultry and livestock. To minimise these effects the amount of the     

实现我国制革工业生态化中的绿色化学研究

This article presents some comments about how to achieve the ecology of tannery industry in China. The keys to achieve he ecology of tannery industry are: 1) Reduce the water consumption of leather-making processing in large scale for cutting down the oading of effluent;2) Decrease the amount of chemicals used for lowering the pollution ;3) Develop “green chemicals“ for eliminating he contamination produced in production of chemicals;4)Cut down the protein waste during leather-making processing,make a full use f the discarded proteins,bring about the “zero effluent“. The measures,which can be conducted for reaching the goal of ecology of annery industry, are split-flow,recovery and recycle of the effluent during leather-making processing;physical techniques instead of raditional chemical procedures; application of biotechnology, and development of biomedicine and biomaterials based on collagen sed for curative treatment,health care,cosmetics and nutrition etc.     

Green Modification of Cellulose Nanocrystals and Their Reinforcement in Nanocomposites of Polylactic Acid

Cellulose nanocrystals(CNCs) of rod-like shape were prepared from degreased cotton using sulfuric acid hydrolysis. The obtained CNC suspension was neutralized using a sodium hydroxide solution to remove the residual sulfuric acid and improve the thermal stability of the CNC particles. Then, poly(ethylene oxide)(PEO) was employed to modify the nanocrystals through entanglement and physical adsorption. The goal was to further improve the thermal stability and weaken the hydrophilicity of CNCs. Original and modified CNCs were dosed into a polylactic acid(PLA) matrix to prepare nanocomposites using a hot compression process. Results of the thermogravimetric analysis showed that the initial thermal decomposition temperature of the modified CNCs showed a 120℃ improvement compared to the original CNCs. That is, the thermal stability of the modified CNCs improved because of their shielding and wrapping by a PEO layer on their surface. Results from scanning electron microscopy and ultraviolet-visible spectrophotometry showed that the compatibility of the modified CNCs with organic PLA improved, which was attributed to the compatibility of the PEO chains adsorbed on the surface of the CNCs. Finally, the results of tensile tests indicated a significant improvement in terms of breaking strength and elongation at the break point.     

肌肉结缔组织与肉嫩度关系研究(英文)

Intramuscular connective tissue(IMCT) has made significant effects on meat tenderness;those effects were executed by the characteristics changes of endomysial and perimysial collagen.The review presents the progress of structural and composition properties of connective tissue as well as contents,solubility and crosslinking of collagen,moreover,the effects of characteristics changes of connective tissue and collagen on meat tenderness and textural properties during postmortem ageing were analyzed and the role of connective tissue in meat tenderization were discussed.     

Toward Sustainable, Economic, and Tailored Production of Cellulose Nanomaterials

This paper introduces a concentrated di-carboxylic acid(DCA) hydrolysis process for the integrated production of thermally stable and carboxylated cellulose nanocrystals(CNCs) and cellulose nanofibrils(CNFs). The DCA hydrolysis process addressed several issues associated with mineral acid hydrolysis for CNC production, such as cellulose loss and acid recovery. The surface and morphological properties of the cellulose nanomaterials resulting from the DCA hydrolysis process can be tailored simply by controlling the severity of DCA hydrolysis. To further reduce cost, a lowtemperature(≤80℃) hydrotropic chemical process using p-toluenesulfonic acid(p-Ts OH) was also introduced to rapidly fractionate raw lignocelluloses for the production of lignin containing cellulose nanofibrils(LCNFs) and lignin nanoparticles(LNPs). The LCNF surface hydrophobicity and morphology can be tailored by controlling the fractionation severity, i.e., the extent of delignification. The lignin also improved the thermal stability of LCNFs. LNPs can be easily separated by diluting the spent acid liquor to below the p-Ts OH minimal hydrotropic concentration of approximately 10%. p-Ts OH can also be easily recovered by re-concentrating the diluted spent liquor after lignin precipitation. We believe that these two novel processes presented here have the potential to achieve true sustainable, economic, and tailored production of cellulose nanomaterials, suitable for a variety of applications.     

Micro-printing performance of durable water-repellent black polyester-spandex fabrics without fluorine and silicone resins北大核心CSCD

Synthetic fibers are widely used because of their stable chemical properties high mechanical strength and low cost. Among them polyester has the largest production and is the most widely used and China is also the country with the largest polyester production in the world. With the technological progress of energy saving and emission reduction of liquid disperse dyes the technology of micro printing of polyester and polyester / spandex fabrics has been realized. Based on the high market share of black polyester / spandex printed fabrics and the increasing market demand for functional finishing (e. g. anti-static finishing water repellent finishing UV resistance finishing etc.), it is of great significance to study the process of one-step short processing of polyester printing and functional finishing using carbon-based materials (e. g. carbon black). Carbon black is a gray-black organic pigment with good antistatic and anti-UV properties. It is an eco-friendly advanced material that integrates printing dyeing and functional finishing. To make up for the lack of color depth of carbon black pigment a disperse black dye and carbon black pigment in the same bath preparation scheme are chosen to prepare a functional liquid carbon black @ disperse black dye (CB-D). Not only does CB-D meet the requirements of deep black printing but also it can simultaneously provide water-repellent finishing to the fabric. In this way the application of organic fluorine or organic silicon resin can be dispensed with. A functional liquid CB-D was prepared by pre-dispersion and zirconium oxide grinding method under the action of abrasive agent AL50 (anionic / non-ionic surfactant complex) . The effects of CB-D mass fraction binder type binder D101 mass fraction baking temperature and time on color (L∗ value) rubbing and soaping colorfastness were investigated by optimizing the printing process of liquid CB-D. At the same time the fixation mechanism of CB-D was investigated and the properties of polyester-spandex printed fabrics were tested. The stability of CB-D and the colorfastness of polyester-spandex printed fabrics to hot-wash effluent were investigated by the rate of change of absorbance. The effect of hot-washing on dye floating in the printed area and dye staining in the non-printed area was characterized by the brightness of the printed area L∗ value and the whiteness of the non-printed area (CIE whiteness W10). The properties of CB-D were characterized by scanning electron microscopy and transmission electron microscopy and the antistatic property water repellency air permeability moisture permeability and tensile breaking strength of the fabrics were tested. (i) The first functional liquid CB-D with excellent stability is prepared by grinding carbon black and disperse black dye composed of orange 288 purple 93 and blue 291:3 in the same bath. (ii) A durable fluorine-free and silicone-free water repellent black polyester spandex fabric is prepared reducing the cost of functional finishing and environmental pollution. The preparation of durable water-repellent polyester spandex fabrics without a functional finishing agent is a new technology. CB-D as functional organic melanin with excellent performance and simple processing is a new low-carbon and eco-friendly material and ecological printing and dyeing process. (i) As for the black polyester spandex fabric prepared by a micro-printing process the color fastness of deep black color is not less than grade 4 the white ground is not stained and the color of wastewater is very low. The printing process requires 5% functional CB-D and 8. 5% binder D101. (ii) The black polyester spandex fabric has excellent and durable water repellency air permeability moisture permeability and antistatic property. The water contact angle is 132° anti-static grade is A and the air permeability and moisture permeability are more than 260 mm / s and 2 880 g / (m2h) respectively. After 30 times of home washing it almost keeps the original excellent performance. (iii) The CB-D prepared based on carbon black and disperse black dye is a colloidal aggregate that easily forms continuous carbon black aggregates on the fiber surface showing more excellent porosity film formation and water repellency while maintaining air permeability and moisture permeability. Carbon black is a low-cost material and the liquid CB-D prepared by modifying carbon black with disperse black dye has a new use in preparing functional textiles with good application prospects. © 2022 Authors. All rights reserved.     

Preparation of Functional Soybean Protein Isolate

Soybean protein isolate(SPI) is a high purity soybean protein product.Its protein content is over 90%.A popular processing method is alkali dissolution and acid precipitation.This method can produce various functional SPIs by changing the temperature,pH,types of alkali and acid,and by different pretreatment and post transformation treatment.The properties addressed in this paper would open a big market for the appli cation of SPI.     

Application of Cellulose Nanofibril as a Wet-end Additive in Papermaking: A Brief Review

Recently,cellulose nanofibril(CNF)has emerged as a promising,sustainable reinforcement with outstanding potential in material science.Owing to the properties of CNF,it has been explored in food,cosmetic,and pharmaceutical applications,as well as in industrial applications such as paints,drill muds,packaging,and papermaking.The application of CNF in papermaking is expected to be implemented in the near future to broaden the commercial market of cellulose.Numerous studies and patents have reported on the manufacturing,properties,and applications of nanocellulose.This present paper focuses on the recent progresses in the application of CNF as a wet-end additive in papermaking.     

Preparation and properties of high-flux and hydrophilic polysulfone superfine fibrous membrane北大核心CSCD

In this paper, the effects of volume percent of glutaraldehyde in chitosan solution on porous structure, hydrophily, mechanical properties and pure water flux of PSF superfine fibrous membrane which was pretreated by oxygen plasma, and then padded with cross-linked chitosan solution. Results show that the pore size decreases obviously, but the hydrophilicity and pure water flux improve significantly after the treatment. The optimum volume percent of glutaraldehyde is 0.40%. In this condition, the treated membrane still has high porous structure, and the average pore diameter is 2. 62 μm. The mechanical properties improve obviously. The membranes also change from hydrophobic property into hydrophilic property. The pure water flux is (1 624. 7±189.5) L/(m2 • h). © 2017 China Silk Association. All rights reserved.     

Ultrasound-assisted Biodiesel Production from Waste Cooking Oil at Room Temperature

Waste cooking oil (WCO) is considered to be a promising alternative for vegetable oils that have been traditionally used for biodiesel production. In this study, WCO with a fairly high free fatty acid content was transesterified into biodiesel in a one-step procedureat room temperature (25℃ ) under ultrasound irradiation and in the presence of potassium hydroxide (KOH) as catalysts. Response surface methodology (RSM) was used to investigate the effects of the methanol/oil molar ratio, reaction time, and catalyst loading on the fatty acid methyl ester (FAME) yield and the biodiesel yield. The optimal reaction conditions for the production of WCO biodiesel were found to be a methanol/oil molar ratio of 8.6:1, a reaction time of 25 min, and a catalyst loading of 2.43 wt%. Under these optimal settings, the FAME and biodiesel yields were 96.4% and 92.7%, respectively. The properties of the resultant WCO biodiesel, including kinetic viscosity, acid number, water content, and flash point, were measured according to ASTM D6751 standards. The obtained results provide useful information for the large-scale production of WCO biodiesel.     

High-value Applications of Nanocellulose

Nanocelluloses, obtained from the biopolymer cellulose, are a class of renewable functional nanomaterials with excellent properties and a broad range of applications. This review mainly illustrates practical and advanced applications of nanocellulose-based materials in the following categories. ① Fire-resistant materials: in the section on these types of materials, the fire-protection property of nanocellulose/clay hybrid composites (clay nanopaper) is illustrated; oriented montmorillonite (MTM) provides barrier properties and low thermal conductivity whereas cellulose nanofibers (CNFs) impart favorable charring. ② Thermal insulation materials: the best way to obtain materials with good heat insulation performance is to decrease the thermal conductivity of such materials. ③ Template materials: nanocellulose can direct the deposition and patterning of materials to form nanoparticles, nanowires, or nanotubes with improved properties.     

Experimental Design as a Tool for the Development of Citric Acid Production by Yarrowia lipolytica Using Glycerol as a Feedstock

Due to the scarcity of fossil fuels in the world, there is increasing interest in the commercial production of biodiesel, which leads to obtaining large amounts of glycerol as a byproduct. If not disposed of properly, glycerol can generate environmental impact. One of the promises, the application of the crude glycerol is the production of citric acid by microbial fermentation. Citric acid is industrially produced by a submerged fermentation process with Aspergillus niger, using sucrose as carbon source, but due to increased demand for citric acid, alternative processes using renewable sources or waste materials as substrates and the cultivation of yeast strains are being studied. The aim of the study was to determine the best culture condition for maximum citric acid synthesis and lower isocitric acid production from crude glycerol through experimental design tool. For this purpose, the yeast strain Yarrowia lipolytica IMUFRJ-50682 was cultivated in nitrogen-limited glycerol-based media. Therefore, glycerol and yeast extract concentrations and agitation speed were evaluated as independent variables. With pure glycerol, the highest citric acid production achieved was 16.5 g/L with an isocitric acid production of 7.7% （in relation to citric acid）. With crude glycerol, citric acid production reduced to 6.7 g/L because of higher biomass yield. Therefore, an increase in the initial carbon to nitrogen molar ratio from 714 to 1,561 was necessary to increase citric acid production to 9.2 g/L, reducing isocitric acid production and to achieve a yield of 0.41 g of citric acid per glycerol consumed. In this condition, less nitrogen source was used, reducing production costs.