Acid Enzymatic Hydrolysis Research Articles

Effects of Different Hydrolysis Methods on the Hydrolysate Characteristics and Photo-Fermentative Hydrogen Production Performance of Corn and Sorghum Straw

The effects of hydrolysis methods (hydrothermal, acid, alkali, hydrothermal-enzyme, acid-enzyme, and alkali-enzyme) on hydrolysate characteristics and photo fermentative hydrogen production (PFHP) of corn straw (CS) and sorghum straw (SS) were investigated. The optimum production of reducing the sugar of straw in different solvent environments was studied by one-step hydrolysis and co-enzymatic hydrolysis pretreatment through a 3,5-dinitrosalicylic acid method. The hydrogen production process by photolytic fermentation of hydrolysates of Rhodobacter sphaeroides HY01 was further analyzed through a gas chromatograph, including the differences in accumulated PFHP yield, chemical oxygen consumption (COD), and volatile fatty acid (VFA) composition. The results showed that the highest reducing sugar yield was obtained by the acid method among one-step hydrolysis. In contrast, acid-enzyme hydrolysis can further increase the reducing sugar yield, which reached 0.42 g·g−1-straw of both straws. Both CS and SS had the highest hydrogen yield from acid-enzyme hydrolysate, 122.72 ± 3.34 mL·g−1-total solid of straw (TS) and 170.04 ± 4.12 mL·g−1-TS, respectively, compared with their acid hydrolysates with 40.46% and 10.53% higher hydrogen yields, respectively. The use of enzymatic hydrolysis showed a significantly higher hydrogen yield for CS compared to SS, indicating that acid hydrolysis was more suitable for SS and acid-enzyme hydrolysis was more suitable for CS.

Quantitation of Collagen Type V in Tissues by High-Performance Liquid Chromatography Coupled to Mass Spectrometry.

A method for quantifying the bovine collagen type V (Col. V) was established based on high-performance liquid chromatography coupled to mass spectrometry by the marker peptide external standard. High-purity Col. V was extracted by the acid-enzyme hydrolysis process, and the marker peptide of Col. V was identified by LCQ mass spectrometry as GPAGPMGLTGR. A broad linear range (0.01-5.00 μg/mL) with a correlation coefficient of 0.9984 was achieved, and the limit of detection and limit of quantification were found to be 3.00 × 10-3 and 6.25 × 10-3 μg/mL, respectively. The method precision was 1.49%. The recovery rate was determined as 97.1-109.6% with a relative standard deviation less than 5%. The proposed method was successfully applied for the determination of Col. V contents in the bovine heart, lung, and cornea, which were 0.72 ± 0.01%, 0.23 ± 0.01%, and 2.89 ± 0.00%, respectively. The results show that the proposed method is more suitable for measuring the content of Col. V in tissue samples compared with the enzyme-linked immunosorbent assay. The marker peptide method has high accuracy and great reproducibility, and will lay a foundation for the extraction and application of Col. V. Impact statement The accurate quantitative method for collagen type V (Col. V) is particularly important in scientific research, disease diagnosis and treatment, and industrial production. In this article, we proposed a high-performance liquid chromatography coupled to mass spectrometry method based on the external standard marker peptide to quantify bovine Col. V. This method shows a higher accuracy and recovery rate than enzyme-linked immunosorbent assay (ELISA), indicating that it is more suitable for measuring the content of Col. V in tissue samples than ELISA. The establishment of this method has laid a solid foundation for the extraction and application of Col. V.

Разработка и валидация методов количественного определения витаминов В1 и В2 в пищевых продуктах с помощью высокоэффективной жидкостной хроматографии с диодно-матричным детектированием

The main sources of vitamins, which are essential substances, are mainly aliment products, foods for special dietary uses and dietary supplements. Therefore, the study of the native content of vitamins in aliment foods has always been of interest. For the chromatographic separation of vitamins, rather versatile C18 columns are used as a stationary phase, which allow one to obtain reliable results using UV detection for vitamin-enriched foods, dietary supplements and vitamin premixes. However, for unfortified foods, this stationary phase in a UV detection system does not give acceptable results. The aim of the work was to develop a technique for the chromatographic separation of vitamins B1 and B2 in unfortified foods using a diode array detector. Material and methods. To prepare samples of foods, concentrated acid hydrolysis (1.0 g of sample and 4 ml of 0.1 N hydrochloric acid) was carried out in a water bath for 30 min at a temperature of 95 °C, followed by enzymatic hydrolysis and degreasing. Further studies of the samples were carried out on an Agilent Technologies 1100 chromatographic system with diode array detection. For the determination of vitamin B1, a Poroshell 120 Hilic column 4.6×150 mm, grain size 2.7 μm was used. As eluent A, a 10 mM aqueous solution of ammonium acetate with 0.5% acetic acid was used, eluent B was acetonitrile (gradient elution: 0-2 min - 90% B, 8-12 min - 50% B, 14-18 min - 90% B). To determine vitamin B2, a C18 Poroshell column 4.6×250 mm, grain size 5 μm was used. As eluent A, a classical phosphate buffer with pH 2.5 was used, eluent B - acetonitrile (gradient elution: 0-5 min - 0% B, 5-15 min - 90% B, 15-22 min - 90% B, 22-24 min - 0% B, 24-27 min - 0% B). Vitamin B1 was detected at a wavelength of 270 nm, vitamin B2 at 450 nm. Under selected conditions, good retention and efficient separation of vitamins B1 (over 16,000 theoretical plates) and B2 (over 20,000 theoretical plates) was observed. Results. It was demonstrated that the HPLC method with diode array detection can be used to quantify the native content of vitamins B1 and B2 in products with a complex food matrix. For the selective determination of these vitamins, a complex of chromatographic conditions is optimal: reverse-phase HPLC for vitamin B2 and hydrophilic interaction chromatography for vitamin B1. A suitable sample preparation of food products for the content of vitamins B1 and B2 under selected chromatographic conditions is concentrated acid-enzymatic hydrolysis. The limit of quantitation for vitamins B1 and B2 was 40 μg/100 g. Comparison of the enzymatic activity of amylorizin and thermostable α-amylase showed that during long-term hydrolysis for 16 hours (37 °С) with amylorizin, the degree of vitamin extraction was two fold higher than during hydrolysis (95 °С, 1 h) with α-amylase. Conclusion. The selected conditions for determining the native content of vitamins B1 and B2 in unfortified and low-fortified foods can be used in practice, which has been proven through their successful validation and practical application on real samples of cereals.

Chemical and Antioxidant Characteristics of Skin-Derived Collagen Obtained by Acid-Enzymatic Hydrolysis of Bigeye Tuna (Thunnus obesus).

The utilization of bigeye tuna skin as a source of collagen has been increasing the value of these skins. In this study, the quality of the skin was studied first. The skin after 14 h freeze-drying showed a high protein level (65.42% ± 0.06%, db), no histamine and a lack of heavy metals. The collagens were extracted through acid and acid-enzymatic methods. The enzymes used were bromelain, papain, pepsin, and trypsin. The two highest-yield collagens were pepsin-soluble collagen (PSC) and bromelain-soluble collagen (BSC). Both were type I collagen, based on SDS-PAGE and FTIR analysis. They dissolved very well in dimethyl sulfoxide and distilled water. The pH ranges were 4.60–4.70 and 4.30–4.40 for PSC and BSC, respectively. PSC and BSC were free from As, Cd, Co, Cr, Cu, and Pb. They showed antioxidant activities, as determined by the DPPH method and the reducing power method. In conclusion, bigeye tuna skin shows good potential as an alternative source of mammalian collagen. Although further work is still required, PSC and BSC showed the potential to be further used as antioxidant compounds in food applications. Other biological tests of these collagens might also lead to other health applications.

Optimization of saccharification prospective from starch of sweet potato roots through acid-enzyme hydrolysis: structural, chemical and elemental profiling

The sweet potato root, a potent source of starch which is being considered as an efficient alternative for fuel ethanol production in recent times. The starchy substrate needs to be subsequently dextrinized and saccharified so as to enhance the utilization of its carbohydrates for ethanol production. In the present investigation, acid-enzyme process was conducted for the dextrinization and saccharification of sweet potato root flour (SPRF). The best optimized condition for dextrinization was achieved with an incubation period of 60 min, temperature 100 ºC and 1M HCl. However, for saccharification, the best result was obtained with an incubation of 18 h, pH 4, temperature 65 ºC and 1000 U concentration of Palkodex®. After the dextrinization process, maximum concentrations of total sugar and hydroxymethylfurfural (HMF) [380.44 ± 3.17 g/kg and 13.28 ± 0.25 mg/g, respectively] were released. Nevertheless, after saccharification, 658.80 ± 7.83 g/kg of total sugar was obtained which was about 73% more than that of dextrinization. After successful dextrinization and saccharification, the structural, chemical and elemental analysis were investigated using techniques such as scanning electron microscopy (SEM), Fourier-transforms infrared spectroscopy (FTIR) and energy-dispersive X-ray fluorescence spectrophotometer (EDXRF), respectively. Effective hydrolysis was demonstrated in thin layer chromatography (TLC) where the HCl was able to generate monomeric sugar such as glucose and maltose. On the other hand, only glucose is synthesized on the mutual effect of HCl and Palkodex®. The SEM findings indicate that the rough structure of both dextrinized and saccharified sample was gained due to the vigorous effect of both acid and enzyme subsequently. The saccharified SPRF when subjected to fermentation with Saccharomyces cerevisiae and Zymomonas mobilis separately, it was observed that Z. mobilis produced more stretching vibration of –OH than S. cerevisiae, which evidenced the better production of bioethanol. Additionally, evaluation of the influence of S. cerevisiae and Z. mobilis through elemental analysis revealed upsurge in the concentrations of S, Cl, Ca, Mn, Fe and Zn and decline in the concentrations of P, K and Cu in the fermented residue of S. cerevisiae and Z. mobilis, however, Z. mobilis showed little more variation than that of S. cerevisiae.

Rye and Oat Agricultural Wastes as Substrate Candidates for Biomass Production of the Non-Conventional Yeast Yarrowia lipolytica

The aim of this study was to test rye straw, rye bran and oat bran hydrolysates as substrates for growth of the yeast Yarrowia lipolytica, a microorganism known to have large biotechnological potential. First, after the combined process of acid-enzymatic hydrolysis, the concentration and composition of fermentable monosaccharides in the obtained hydrolysates were analyzed. Glucose was the main sugar, followed by xylose and arabinose. Rye bran hydrolysate had the highest sugar content—80.8 g/L. The results showed that this yeast was able to grow on low-cost medium and produce biomass that could be used as a feed in the form of single cell protein. The biomass of yeast grown in oat bran hydrolysate was over 9 g/L after 120 h, with the biomass total yield and total productivity values of 0.141 g/g and 0.078 g/h, respectively. The protein contents in yeast biomass were in the range of 30.5–44.5% of dry weight. Results obtained from Y. lipolytica cultivated in rye bran showed high content of exogenous amino acid (leucine 3.38 g, lysine 2.93 g, threonine 2.31 g/100 g of dry mass) and spectrum of unsaturated fatty acid with predominantly oleic acid—59.28%. In conclusion, these results demonstrate that lignocellulosic agricultural waste, after hydrolysis, could be efficiently converted to feed-related yeast biomass.

The cascade biorefinery approach for the valorization of the spent coffee grounds

Six million tons of Coffee Spent Grounds (SCG) are produced every year all around the world. Their physical and chemical characterization, rich in high value molecules and organic compounds, make SCG ideal for the recovery of bioactive molecules and bioenergy production according to the “cascade biorefinery approach”. This work investigates the effects of the implementation of sequential processes for the recovery of the coffee oil, rich in valuable molecules, and the productions of bioethanol and biogas from SCG. The use of a 50:50 (v/v) ethanol-iso-propanol mixture allowed a coffee oil recovery of about 16% w/w. In particular, the extracted coffee oil was rich in tocopherols (about 15 mg/100 g SCG). On the other hand, n-hexane showed a lower performance in terms of coffee oil extraction (10% w/w) but allowed for the extraction of different molecules: linoleic and palmitic acids (38% and 34% w/w of the coffee oil, respectively) and of Cafestol (383 mg/100g SCG) and Kahweol (194 mg/100g SCG). The extracted SCG underwent to an acid-enzymatic hydrolysis process followed by a solid/liquid separation. The liquid fraction was then used for the bioethanol production which reached the final concentration of 50 g/L, while the solid fraction was used for biogas production by Anaerobic Digestion. The final methane yield resulted in a production of about 250 NLCH4/kgVS. A complete train of operations, composing a biorefinery approach, can be therefore adopted to fully valorise this particular organic waste.

Nutrient value of fruit in promising strawberry varieties

One of the current areas in research of fruit and berry crops is the study of their nutritional value and micronutrient composition. Valuable chemical composition of the strawberry determines a wide spectrum of its utilization not only as fresh fruit, but also as a raw material for food industry. Breeding requirements for contemporary strawberry varieties together with yield, large-fruit, important taste and dietary qualities of fruit provide for higher content of biologic active substances. The aim of the research was an integrated assessment of strawberry fruit for content of nutrients and bioactive compounds, as well as mineral elements, and its antioxidant activity. Material and methods. The objects of investigation were berries of 5 strawberry varieties bred in the I.V. Michurin Scientific Centre (Lakomaya, Prazdnichnaya, Privlekatelnaya, Urozhaynaya CGL, Feyerverk) and 9 foreign varieties (Vima Zanta, Dukat, Zefir, Kama, Maryshka, Red Gauntlet, Festivalnaya romashka, Honey, Elsanta) which are promising for cultivation in the Black Soil Region of Russia. The content of soluble solids was determined by the refractometric method, sugars - by Bertrand's method, pectins - by the volumetric method, anthocyanins - by pH-differential spectrophotometry. Total content of antioxidants was defined by amperometric method with recalculation per quercetin. Determination of vitamin B1 was carried out using the fluorometric thiochrome method, vitamin B2 - by fluorometric titration with riboflavin-binding apoprotein after acid-enzymatic hydrolysis, ascorbic acid, vitamin E (tocopherols), niacin, organic and hydroxycinnamic acids - by HPLC, flavonols - spectrophotometrically, minerals and trace elements - by atomic absorption method. Results and discussion. A significant variation in the chemical composition indices depending on the varietal characteristics was found. Strawberry fruit accumulated 8.5-12.0% soluble solids, 5.9-8.7% sugars, 1.5-2.1% of fibre, 0.78-1.12% pectin substances, 0.89-1.45% organic acid; 100 g contain 33.5-48.2 mg vitamin C, 18.3-108.5 mg anthocyanins, 0.024-0.041 mg vitamin B1, 0.012-0.029 mg vitamin B2, 0.10-0.26 mg niacin, 0.26-0.60 mg TE vitamin E, 102-270 mg potassium, 0.15-0.95 mg iron; total antioxidant activity ranged within 180.8-350.0 mg/100 g. High level of anthocyan accumulation (over 80.0 mg/100 g) was observed in Privlekatelnaya, Lakomaya and Feyerverk strawberry varieties. Urozhaynaya CGL, Privlekatelnaya and Lakomaya varieties were characterized by dessert taste. According to the results of the studies Privlekatelnaya variety stood out because of the high complex accumulation of vitamin C, anthocyanins, and high total antioxidant activity. These varieties are recommended for both fresh use and for freezing, as well as for production of functional foods. Conclusion. The obtained data are of interest for further inclusion in the Tables of the chemical composition of Russian food products.

Over production of fermentable sugar for bioethanol production from carbohydrate-rich Malaysian food waste via sequential acid-enzymatic hydrolysis pretreatment

In Malaysia, the amount of food waste produced is estimated at approximately 70% of total municipal solid waste generated and characterised by high amount of carbohydrate polymers such as starch, cellulose, and sugars. Considering the beneficial organic fraction contained, its utilization as an alternative substrate specifically for bioethanol production has receiving more attention. However, the sustainable production of bioethanol from food waste is linked to the efficient pretreatment needed for higher production of fermentable sugar prior to fermentation. In this work, a modified sequential acid-enzymatic hydrolysis process has been developed to produce high concentration of fermentable sugars; glucose, sucrose, fructose and maltose. The process started with hydrothermal and dilute acid pretreatment by hydrochloric acid (HCl) and sulphuric acid (H2SO4) which aim to degrade larger molecules of polysaccharide before accessible for further steps of enzymatic hydrolysis by glucoamylase. A kinetic model is proposed to perform an optimal hydrolysis for obtaining high fermentable sugars. The results suggested that a significant increase in fermentable sugar production (2.04-folds) with conversion efficiency of 86.8% was observed via sequential acid-enzymatic pretreatment as compared to dilute acid pretreatment (∼42.4% conversion efficiency). The bioethanol production by Saccharomyces cerevisiae utilizing fermentable sugar obtained shows ethanol yield of 0.42g/g with conversion efficiency of 85.38% based on the theoretical yield was achieved. The finding indicates that food waste can be considered as a promising substrate for bioethanol production.

Bioconversion of pretreated sugarcane bagasse using enzymatic and acid followed by enzymatic hydrolysis approaches for bioethanol production

The present study was focused on effective utilization of sugarcane bagasse holocellulose for bioethanol production. Saccharification of sugarcane bagasse was performed by employing two strategies viz. direct enzymatic hydrolysis and acid followed by enzymatic hydrolysis. In first case enzymatic saccharification of ammonia treated sugarcane bagasse was carried out using in house developed cocktail of cellulases-hemicellulases and maximum 614 mg/g reducing sugars were produced. By using second strategy, selective fractionation of hemicellulosic sugars was obtained by dilute acid hydrolysis which yielded 41.19 g/l of reducing sugars with pentoses as the major end product. The residual cellulose rich bagasse after alkali treatment was enzymatically hydrolyzed using commercial cellulases which yielded 571 mg/g of reducing sugars with hexoses as the major product. The sugars produced by both the strategies were used for ethanol production separately by suitable hexoses and pentose utilizing yeast strains. By comparative evaluation, it was revealed that direct saccharification of sugarcane bagasse using in-house developed cocktail of cellulases-hemicellulases was more advantageous as compared to acid-enzymatic hydrolysis for bioethnol production.

Sequential hydrolysis of oat straw and hydrogen production from hydrolysates: Role of hydrolysates constituents

Sequential hydrolysis of oat straw and hydrogen (H2) production from hydrolysates and hydrolysates constituents were investigated. One acid-enzymatic and two acid-alkaline-enzymatic procedures were assessed to measure their capability to convert hemicellulose and cellulose from oat straw to sugars. Acid hydrolysis, using HCl, resulted effective to depolymerize hemicellulose (81%) and also facilitated the activity of cellulases over remaining fiber. When alkaline hydrolysis, using KOH/NaClO2/KOH or NaOH/H2O2, were applied, the depolymerization of cellulose was only slightly increased. Total sugar recoveries ranged from 69 to 79% in the different sequential hydrolysis tested. Hence, hydrolysates from sequential acid-enzymatic hydrolysis were used as substrates for H2 production in batch assays. The enzymatic hydrolysate produced a higher H2 molar yield (2.39 mol H2/mol reducing sugars) than the acid hydrolysate (1.1 mol H2/mol reducing sugars). It was found that lower H2 production from the acid hydrolysate was partially due to a lower H2 yield from arabinose and not to measured microbial inhibitors (furfural, hydroxymethylfurfural, vanillin and syringaldehyde). Also, it was found that the commercial enzyme (Celluclast 1.5 L) was easily fermented, and greatly contributed to the H2 production. This is the first study that provides experimental evidence of H2 production from fermentation of a commercial enzyme.

Evaluation of jumbo squid (Dosidicus gigas) byproduct hydrolysates obtained by acid-enzymatic hydrolysis and by autohydrolysis in practical diets for Pacific white shrimp (Litopenaeus vannamei)

The marine bioprocessing industry offers great potential to utilize byproducts for fish meal replacement in aquafeeds. Jumbo squid is an important fishery commodity in Mexico, but only the mantle is marketed. Head, fins, guts and tentacles are discarded in spite of being protein-rich byproducts. This study evaluated the use of two jumbo squid byproduct hydrolysates obtained by acid-enzymatic hydrolysis (AEH) and by autohydrolysis (AH) as ingredients in practical diets for shrimp. The hydrolysates were included at levels of 2.5 and 5.0% of the diet dry weight in four practical diets, including a control diet without hydrolysate. Shrimp growth and survival were not significantly affected by the dietary treatments. Postharvest quality of abdominal muscle was evaluated in terms of proximate composition and sensory evaluation. Significantly higher crude protein was observed in the muscle of shrimp fed the highest hydrolysate levels, AH 5% (204.8 g kg - 1) or AEH 5% (201.3 g kg - 1). Sensory analysis of cooked muscle showed significant differences for all variables evaluated: color, odor, flavor, and firmness. It was concluded that Jumbo squid byproducts can be successfully processed by autohydrolysis or acid-enzymatic hydrolysis, and that up to 5.0% of the hydrolysates can be incorporated into shrimp diets without affecting growth or survival.

Batch ethanol production from cassava (Manihot esculenta Crantz.) flour using Saccharomyces cerevisiae cells immobilized in calcium alginate

The objective of this research was to saccharify cassava flour by acid-acid and acid-enzyme hydrolysis and further conversion of the resulting sugar into ethanol by fermenting with the immobilized (in Ca-alginate) cells of Saccharomyces cerevisiae. The saccharification resulted in higher total sugar recovery by acid-enzyme hydrolysis (72.88 %) than by enzyme-enzyme hydrolysis (58.1 %). Further study on ethanol production was carried out using the hydrolysate obtained from acid-enzyme hydrolysis. The growth of the yeast started in the log phage and maximum ethanol (189 ± 3.1 g ethanol/kg flour) production was achieved with 94.74 ± 2.187 % sugar conversion during the stationary phase.

DYNAMIC RHEOLOGICAL PROPERTY OF TYPE I COLLAGEN FIBRILS

Collagen fibril (CF) has been a hot research topic in biomedical materials and tissue engineering for decades, because of its excellent physicochemical properties and biological performance. In the paper, type I CF was successfully prepared with acid-enzyme hydrolysis method, which was characterized by atomic force microscope (AFM), infrared spectroscopic analysis (FTIR) and dynamic rheological property testing. AFM results showed that CF had a uniform size distribution, that is, 135 nm ± 5.00 nm, and enjoyed the D cycle horizontally striped structure. Temperature variation also has an effect on CF structures. At 45°C, significant changes took place in the secondary structure of collagen. Dynamic rheological results showed that CF thermotropism occurred at 45.59°C. In addition, under 25°C and at a concentration ranging from 0.5 mg/mL to 2.0 mg/mL, angular frequency growth increased elastic modulus and the liquid carrying factor of CF solution, and decreased complex viscosity and mechanical loss. The results provide a new and reliable theoretical foundation for processing, molding and application of natural CF.

Bioaugmented cellulosic hydrogen production from cornstalk by integrating dilute acid-enzyme hydrolysis and dark fermentation

The cellulosic hydrogen production from cornstalk based on the integrating dilute acid with enzymatic hydrolysis was investigated using response surface methodology (RSM). The dilute acid pretreatment of cornstalk with the concentration of 1.5% H 2SO 4, 121 °C and 60 min was found to be most effective in the first prehydrolysis stage. Thereafter, the process parameters of enzymatic hydrolysis of the solid residue, which derived from acid-pretreated cornstalk, were further optimized by a three factor-five level central composite design (CCD) with temperature ( X 1 ), pH ( X 2 ), and enzyme loading ( X 3 ) as the independent variables. The optimal parameters of enzymatic hydrolysis of substrate were observed to be 52 °C of temperature, pH 4.8 and 9.4 IU/g of enzyme loading. In this case, the total soluble sugar obtained in the hydrolysis stages was 562.1 ± 6.9 mg/g-TVS, and the maximum hydrogen yield from cornstalk by anaerobic mixed microflora was 209.8 ml/g-TVS. Biodegradation mechanism of cornstalk for hydrogen production was further discussed based on analyzing changes in the physical structure and chemical composition of cornstalk during the hydrolysis and fermentation processes.

Effects of processing conditions on hydrolysis of cassava starch

Different procedures for hydrolyzing raw cassava starch were studied, namely: acid, acid-enzyme and enzyme-enzyme hydrolysis. The effects of temperature, initial cassava starch concentration, acid concentration and time on acid hydrolysis using dilute hydrochloric acid were investigated. In addition, the effect of initial cassava starch concentration and time on acid-enzyme hydrolysis with HCl/fungalmyl/amyloglucosidase and HCl/termamyl/amyloglucosidase as well as the enzyme-enzyme hydrolysis with fungalmyl/amyloglucosidase and termamyl/amyloglucosidase were also investigated and the local optimum operating conditions and the yield from the three methods were compared. The results showed that in acid hydrolysis the local optimum operating conditions were: 15% cassava starch concentration, 0.5M HCl, at 70 oC and 10 h operating time which produced 32.5 g/l reducing sugar concentration and dextrose equivalent (DE) of 22. The acid-enzyme hydrolysis with HCl/fungalmyl/amyloglucosidase, using 30% initial cassava starch concentration and total effective operating time of 50 h, produced 72 g/l reducing sugar concentration and DE of 24.8 and was the better of the two acid-enzyme hydrolysis studied. The best procedure was the enzyme-enzyme hydrolysis with termamyl/amyloglucosidase using 30% initial cassava starch concentration, which produced 152 g/l reducing sugar concentration and DE of 50.9. The total effective operating time was 60 h.Keywords:Cassava starch, hydrolysis, enzyme, dextrose equivalent.Ifr Journal of Science Vol. 8 (2) 2006: pp. 115-126

Vitamin B2 content determination in liver paste by using acid and acid-enzyme hydrolysis

Vitamin B2 is available in foodstuff in the form of coenzyme and in free form. For its content determination a few procedures should be performed (deliberation from a complex, extraction of free and deliberated form) and detection, identification and quantification. There is a particular problem in determination of vitamin B2 in the meat products. For a determination of total vitamin B2 content in liver paste two preparation procedures are compared: acid and acid-enzymatic hydrolysis. The aim of this study thus, was to compare the effectivenes of these two different procedures for vitamin B2 content determination in liver paste. High pressure liquid chromatography (HPLC) method with fluorescence detector, as specific and adequately sensitive for the foodstuff of a complex composition with a natural vitamin content, was used for determination of vitamin B2 in liver paste. Acid hydrolysis was performed with the application 0.1 M hydrochloric acid in a pressure cooker, and enzymatic hydrolysis was performed with the 10% takadiastase on 45 degrees C within four hours. Ten samples of liver paste from the supply of the Serbian Army were examined. Separation was performed on the analytical column Nucleosil 50-5 C18 with mobile phase 450 ml CH3OH + 20 ml 5 mM CH3COONH4, and detection on the fluorescent detector with the variable wave length. Both methods were validated: examining a detection limit, quantification limit, specificity (because of a possible B2 vitamin interference with reagents), linearity of a peak area and standard concentration of B2 vitamin ratio in the range from 0.05 microg/ml to 2 microg/ml, precision for the 0.05 microg/ml concentration and recovery. All the previously examined parameters validated both methods as specific, precise and reproductive, with a high recovery (98.5% for acid and 98.2% for acid-enzymatic hydrolysis), as well as linearity in a range that significantly superseded the expected content in the samples (r = 0.9994, and r = 0.99987). Hydrolysis procedures make a sample suitable for vitamin B2 determination. In the liver paste samples a high content of vitamin B2 was determined: 0.83 mg/100 g after acid hydrolysis, and 0.909 mg/100 g after acid-enzyme hydrolysis. There were statistically significantly higher values determined after the acid-enzyme hydrolysis (p < 0.05). Using acid-enzyme hydrolysis and separation instrument technique (liquid chromatography) with a fluorescent detector as detection system, statistically significantly greater vitamin B2 quantities were determined than after using acid hydrolysis procedure. Vitamin B2 content determined in ten liver paste samples was high (0.881-0.936 mg/100 g) indicating that this meat product is a good vitamin B2 source.

Glucose, insulin, gastric inhibitory polypeptide and pancreatic polypeptide responses to polycose during pregnancy

Polycose, a glucose polymer produced by controlled acid enzyme hydrolysis of starch, has been proposed as an effective substitute for glucose solution in antepartum screening for glucose intolerance. The purposes of this study were to examine the glucose and hormonal responses to 50 g of glucose polymer (polycose) solution in pregnant and nonpregnant women and to compare these with the standard 50-g oral glucose challenge test. In addition, the subject's acceptance of the glucose polymer solution was evaluated. Subjects were examined after an overnight fast following a 3-day dietary preparation. There was no difference in glucose or insulin responses to glucose or polycose in either pregnant or nonpregnant women. In contrast, the gastric inhibitory polypeptide response to polycose was significantly higher than to glucose. No differences were observed in plasma pancreatic polypeptide responses to glucose and polycose. In the pregnant subjects, even though the plasma insulin response to carbohydrate challenge was higher than in the nonpregnant subjects, gastric inhibitory polypeptide levels were significantly lower. Patient satisfaction was similar with both carbohydrate solutions. These data suggest that polycose can be used as a substitute for glucose in antepartum testing, although the differences in the hormonal responses should be recognized. Further studies in a subject population with carbohydrate intolerance will be required before polycose use can be recommended in abnormal states.