Starchy Materials Research Articles

Coeliacs cannot live by gluten‐free bread alone – every once in awhile they need antioxidants

SummaryThis comprehensive review, covering scientific papers published from 2013 until now, deals with the bioactivity of available gluten‐free matrices. For this purpose, cereals (rice, maize, sorghum, teff and millets), pseudocereals (buckwheat, quinoa and amaranth) and noncereals (pulses as lentils, fruits as bananas, vegetables as potatoes and nuts as chestnuts, among others) sources are studied. The current trends in enhancing the antioxidant activity of gluten‐free baked products by incorporating natural bioactive compounds are presented. This review covers a wide range of natural bioactive sources such as starchy materials or its by‐products; spices, herbs or green plant materials and vegetable and seeds or fruits. Special emphasis was put on describing the changes in antioxidant activity that can occur, between raw matrices and enriched final products, during baking process. Possible future trends in the improvement of antioxidant properties of gluten‐free baked products, based on bioactive sources which have already been applied in the gluten bread industry, were also discussed.

Impact of Thermo-alkaline Pretreatment on the Thermophilic Anaerobic Digestion of Wheat Plant Residues

Background: Wheat plant (WP) residues could be efficiently used as substrate for biogas production via anaerobic digestion (AD). It is a mixture of starchy and lignocellulosic materials. The hydrolysis of wheat plant is the ratelimiting step of its AD. An efficient pretreatment can facilitate the wheat plant hydrolysis and accordingly enhance the AD’s efficiency. The aim of this study was to investigate the effects of thermo-alkaline pretreatment on the WP structure as well as the yield of thermophilic anaerobic digestion of WP. Methods: Anaerobic sludge was used as inoculum. Wheat plant (WP) including its straw and grains was used as substrate. The impact of sodium hydroxide pretreatment (8% w/w) on the thermophilic anaerobic digestion (55 °C) of wheat plant using anaerobic sludge in batch reactors was investigated. Pretreatments were performed at different temperatures of 0, 25, 50, 75, and 100 °C for 60 min. Results: The methane and biogas yields of the untreated WP were 182.1 and 287.3 mL/g VS, respectively. The pretreatments at 50 °C and 75 °C led to the highest methane yields of 232.9 and 358.6 mL/g VS, respectively, while the other pretreatments had no positive effects on the methane yield. The results of scanning electron microscopy showed that the surface of the WP was effectively destructed after pretreatment at 75 °C when compared with the untreated WP. Conclusion: Thermo-alkaline pretreatment (specially at 75 °C for 60 min) could efficiently enhance the yield of anaerobic digestion of wheat plant. Keywords: Anaerobic digestion, biomethane, NaOH, thermo-alkaline pretreatment, wheat plant.

Physical and structural changes induced by high pressure on corn starch, rice flour and waxy rice flour

The impact of high pressure (HP) processing on corn starch, rice flour and waxy rice flour was investigated as a function of pressure level (400MPa; 600MPa), pressure holding time (5min; 10min), and temperature (20°C; 40°C). Samples were pre-conditioned (final moisture level: 40g/100g) before HP treatments. Both the HP treated and the untreated raw materials were evaluated for pasting properties and solvent retention capacity, and investigated by differential scanning calorimetry, X-ray diffractometry and environmental scanning electron microscopy. Different pasting behaviors and solvent retention capacities were evidenced according to the applied pressure. Corn starch presented a slower gelatinization trend when treated at 600MPa. Corn starch and rice flour treated at 600MPa showed a higher retention capacity of carbonate and lactic acid solvents, respectively. Differential scanning calorimetry and environmental scanning electron microscopy investigations highlighted that HP affected the starch structure of rice flour and corn starch. Few variations were evidenced in waxy rice flour. These results can assist in advancing the HP processing knowledge, as the possibility to successfully process raw samples in a very high sample-to-water concentration level was evidenced. Industrial relevanceThis work investigates the effect of high pressure as a potential technique to modify the processing characteristics of starchy materials without using high temperature. In this case the starches were processed in the powder form - and not as a slurry as in previously reported studies - showing the flexibility of the HP treatment. The relevance for industrial application is the possibility to change the structure of flour starches, and thus modifying the processability of the mentioned products.

Effect of technological parameters the process of ethanol production in the saccharification of barley

Tenderized saccharification process is a mass of the cores in the production of ethanol from starch-containing raw materials. Saccharification of starchy raw materials needed because main production races alcohol yeast do not synthesize and amylolytic enzymes are not able to use in their metabolism Nepo-starch, facility and internalize only mono – and disaccharides. The main aim is to obtain a mash saccharification with a high content of fermentable carbohydrates. The main objective is to obtain a saccharification wort with a high con-zhaniem fermentable carbohydrates. From the course of the saccharification process, the quality of the alcohol depends on the completeness of the fermentation of starch raw materials and product yield. On saccharification sodden mass affected by temperature, pH, glucoamylase dosage and duration of the process. From these factors depend technical-economic production figures. Saccharification boiled barley weight carried glucoamylase enzyme preparation bios 800 A at the rate of 6.0 units per g starch SFS. Control is tenderized weight obtained using one enzyme preparation Alfaferm 3500 A at a dose of 1.0 units per g starch AS. Saccharification takes place at a temperature of 50–65 0 C and pH 4.0–5.5 for 120 minutes. pH was adjusted weight tenderized by making it in sulfuric acid. The saccharification process dynamics studied glucose accumulation in the barley wort in function of temperature, pH, and the dosage of glucoamylase. Samples for glucose determination were taken every 30 minutes. At a temperature of 65 0 C in the first 30 minutes of the accumulation of glucose goes fast, then suddenly slows down, it is possible due to the inactivation of glucoamylase due to changes in the structure of the enzyme molecule. The maximum amount of glucose stored at a temperature of 60 0 C and 11.1 g / cm3, which corresponds to the optimum action of glucoamylase enzyme preparation used. The concentration of hydrogen ions (pH) has a multifaceted effect on the process of saccharification. On the one hand alter H + ionization of the active site of glucoamylase conformational state and, on the other hand influence the stability of the tertiary structure of glucoamylase. Maximum glucose accumulation is observed at pH 4.5 and 11.9 g / cm3. With increasing the glucoamylase dosage increases the effective formation of enzyme-substrate complexes, and hence the rate of hydrolysis of starch. When applying multienzyme complex observed increase in the amount of glucose by 34.7%, compared with the control. The degree of starch hydrolysis increases as it becomes more accessible to the action of saccharifying enzymes by the hydrolysis of proteins and membranes barley containing hemicellulose. Application of multienzyme composition allows to reduce the consumption of glucoamylase to 4.0 units per g starch SFS, SFS instead of 6.0 units per gram of starch in control.

Acha (<i>Digitaria exilis</i>) Malt as a Source of Enzyme for Bio-Ethanol Production from Starchy Materials

Acha (<i>Digitaria exilis</i>) Malt as a Source of Enzyme for Bio-Ethanol Production from Starchy Materials

Acha ( Digitaria exilis ) Malt as a Source of Enzyme for Bio-Ethanol Production from Starchy Materials

Three acha varieties were malted and their enzyme activities were compared with that of barley malt. During the malting, the maximum amylase activity was achieved on day 3 for white and black acha but in the case of brown acha, the maximum activity was obtained on day 4. Under the optima malting conditions, all the three acha varieties gave higher amylase activity than barley malt. Of the three varieties of acha, white acha gave the highest glucoamylase activity (50 U/ml) and the least was exhibited by barley malt (26 U/ml). Application of malted acha as a source of enzyme for simultaneous hydrolysis and ethanol fermentation of two substrates (cassava and corn flour) was investigated under various conditions. Cassava flour yielded higher ethanol than corn flour under all the conditions investigated. Comparison of acha malt with koji enzymes for simultaneous hydrolysis and ethanol fermentation under various conditions showed that acha malt enzymes are superior to koji enzymes (microbial enzymes) under the three conditions investigated. Furthermore, regardless of the substrate used, gelatinization of starch improved ethanol productivity and yields. Incubating a mixture of raw starch and acha malt at 50 o C for 30 minutes before inoculation of yeast cells improved the ethanol production but the final ethanol concentration was not as high as the value obtained with gelatinized starch. These results have demonstrated that acha malt has great potential application in brewery and ethanol production industries. Keywords: Acha malt, Koji enzymes, Bio-ethanol, Cassava flour, Corn flour

Enhanced direct fermentation of cassava to butanol by Clostridium species strain BOH3 in cofactor-mediated medium.

BackgroundThe main challenge of cassava-based biobutanol production is to enhance the simultaneous saccharification and fermentation with high hyperamylolytic activity and butanol yield. Manipulation of cofactor [e.g., Ca2+ and NAD/(P)H] levels as a potential tool to modulate carbon flux plays a key role in the cassava hydrolysis capacity and butanol productivity. Here, we aimed to develop a technology for enhancing butanol production with simultaneous hydrolysis of cassava (a typical model as a non-cereal starchy material) using a cofactor-dependent modulation method to maximize the production efficacy of biobutanol by Clostridium sp. stain BOH3.ResultsSupplementing CaCO3 to the medium containing cassava significantly promotes activities of α-amylase responsible for cassava hydrolysis and butanol production due to the role of Ca2+ cofactor-dependent pathway in conversion of cassava starch to reducing sugar and its buffering capacity. Also, after applying redox modulation with l-tryptophan (a precursor as de novo synthesis of NADH and NADPH), the levels of cofactor NADH and NADPH increased significantly by 67 % in the native cofactor-dependent system of the wild-type Clostridium sp. stain BOH3. Increasing availability of NADH and NADPH improved activities of NADH- and NADPH-dependent butanol dehydrogenases, and thus could selectively open the valve of carbon flux toward the more reduced product, butanol, against the more oxidized acid or acetone products. By combining CaCO3 and l-tryptophan, 17.8 g/L butanol with a yield of 30 % and a productivity of 0.25 g/L h was obtained with a hydrolytic capacity of 88 % towards cassava in a defined medium. The metabolic patterns were shifted towards more reduced metabolites as reflected by higher butanol–acetone ratio (76 %) and butanol–bioacid ratio (500 %).ConclusionsThe strategy of altering enzyme cofactor supply may provide an alternative tool to enhance the stimulation of saccharification and fermentation in a cofactor-dependent production system. While genetic engineering focuses on strain improvement to enhance butanol production, cofactor technology can fully exploit the productivity of a strain and maximize the production efficiency.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-015-0351-7) contains supplementary material, which is available to authorized users.

Physicochemical evaluation of Satva extracted from male and female plants of Guduchi (Tinospora cordifolia (Willd.) Miers)

Introduction: Guduchi (Tinospora cordifolia (Willd.) Miers) is a commonly used Ayurvedic herb, with wide range of therapeutic applications. The plant is dioecious, however, this factor is not given proper consideration while collecting the plant material for medicinal purposes. Minimal studies are available on male and female varieties of Guduchi. Guduchi Satva, the aqueous extracted starchy material of Guduchi stem is a widely used and highly potent single drug formulation. Factors such as type of species and stem size could affect the final yield and physicochemical profile of Guduchi Satva. However, no published information on such variations is available so far. Aims and Objectives: The present study is planned to evaluate quantitative variation and physicochemical profile in Satva extracted from male and female varieties of Guduchi. Materials and Methods: Total ten batches (5 batches from each group) of Guduchi Satva were prepared to get an average data and findings were systematically recorded. The obtained Satva was further subjected to relevant physicochemical parameters, qualitative tests for various functional groups and total alkaloid contents. Results: The study results revealed that average yield of dried Satva was more in female (3.18%) than male variety (2.25%). Variations in Organoleptic characters were insignificant. All functional groups were found to be same in each sample. Extractive values (water soluble extractive and methanol soluble extractive) and total alkaloid contents were found bit higher in Satva from female variety. The obtained data can be considered as standard for future studies.

Performance of Mixed Cellulase-Amylase Immobilized on PSF Membrane Support via Cross-Linked with Glutaraldehyde in Enzymatic Hydrolysis

A Cellulase and amylase are important enzymes for hydrolysis of cellulose and starchy material into the glucose. The performance of the mixed cellulose-amylase immobilized on polysulfone membrane (PSF) by cross-linked with glutaraldehyde was investigated. PSF membrane consists of 1-methyl-2-pyrolidone (NMP) as a solvent and using polyvinylpyrolidone (PVP) as an additive was developed. The study highlighted in the surface structure of PSF membrane, stability of the immobilized enzyme and reusability of the immobilized enzyme. Morphology studied using FESEM analysis indicated a good distribution of the pores was formed on the surface of the PSF membrane. The immobilization process shown no effect on the membrane structure and it was stable to be used as a support in immobilization process. The optimum operating condition for enzymatic hydrolysis of mixed cellulase-amylase on PSF membrane was 50°C and pH 5. The maximum glucose produced at the optimum condition was 4.843g/ml. The study also indicated that immobilized mixed cellulase-amylase achieved a maximum rate of reaction at first recycle of reusable before the rate of reaction decreased rapidly after 5 reusable hydrolysis cycles.

Truly Absorbed Microbial Protein Synthesis, Rumen Bypass Protein, Endogenous Protein, and Total Metabolizable Protein from Starchy and Protein-Rich Raw Materials: Model Comparison and Predictions.

This study was carried out to measure truly absorbed microbial protein synthesis, rumen bypass protein, and endogenous protein loss, as well as total metabolizable protein, from starchy and protein-rich raw feed materials with model comparisons. Predictions by the DVE2010 system as a more mechanistic model were compared with those of two other models, DVE1994 and NRC-2001, that are frequently used in common international feeding practice. DVE1994 predictions for intestinally digestible rumen undegradable protein (ARUP) for starchy concentrates were higher (27 vs 18 g/kg DM, p < 0.05, SEM = 1.2) than predictions by the NRC-2001, whereas there was no difference in predictions for ARUP from protein concentrates among the three models. DVE2010 and NRC-2001 had highest estimations of intestinally digestible microbial protein for starchy (92 g/kg DM in DVE2010 vs 46 g/kg DM in NRC-2001 and 67 g/kg DM in DVE1994, p < 0.05 SEM = 4) and protein concentrates (69 g/kg DM in NRC-2001 vs 31 g/kg DM in DVE1994 and 49 g/kg DM in DVE2010, p < 0.05 SEM = 4), respectively. Potential protein supplies predicted by tested models from starchy and protein concentrates are widely different, and comparable direct measurements are needed to evaluate the actual ability of different models to predict the potential protein supply to dairy cows from different feedstuffs.

Effect of Cocopeat Addition to Some Properties of Cassava Starch‐Based Foam

SummaryStarch‐based foam is a packaging materials made mainly from starchy materials which, as renewable resources, have the prospect of substituting synthetic styrofoam. Starch alone produced foam with poor mechanical properties. For that reason, cocopeat was added as a fiber reinforcement and blended with polyvinyl alcohol for improving the foam properties. This research investigated the effect of cassava starch and cocopeat ratio on the physical and mechanical properties of the biofoams prepared by addition of one part of cocopeat to 2, 3, and 4 parts of cassava starch followed by thermopressing technique at 150 °C for 6 min. Addition of cocopeat caused an increase in foam thickness (1.796–1.909 mm) but reduced its density (0.965–0.888 g/cm3), and the mixture produced foams with moderate modulus of elasticity (134–169 MPa) and high modulus of rupture (4.28–4.42 MPa). The biofoams had good mechanical properties and also had a high capability to absorb water (25.1–34.5%) in 3 min. This made the biofoams only suitable for packing low moisture products. Its high water absorption capability also influenced its biodegradability.

Biochemical Screening of Different Types of Sweet Potato for Bioethanol Production

Today the present scenario is focused at energy production from agricultural biomass which has emerged as one of the dependable non-traditional feedstock for the production ofbioethanol. Production of this renewable fuel, especially from starchy materials such as tuber crops, holds a remarkable potential to meet the future energy. In recent years, with the increase in price of fossil fuels, the demand of biofuel production from tuber crops such as sweet potato has increased by leaps and bounds. Among different tuber crops, sweet potato (Ipomoea batatas L.) has been considered as a promising substrate for bioethanol production and has become very important to meet the future energy crisis in developing countries. In our present study, eight varieties of sweet potatoes were collected from different region of Odisha and biochemically analysed for ethanol production. Among them, the Gouri variety collected from Odisha University of Agriculture and Technology, Bhubaneswar, exhibited maximum amount of starch (293.69±2.9 gkg−1) and sugar (326.09±2.1 gkg−1) followed by Sree Krishna variety. The Gouri type also produced maximum ethanol of1 4 7.7±0.4 gkg−1 and showed ethanol yield of 90.6%. The other varieties were exhibiting low starch and sugar content (approximately 15% less) than the Gouri variety. As the Gouri variety was more potent for starch and sugar synthesis, so this variety can be utilised for enhanced bioethanol production.

МЕТОДЫ ПОДГОТОВКИ РАСТИТЕЛЬНОГО СЫРЬЯ К БИОКОНВЕРСИИ В КОРМОВЫЕ ПРОДУКТЫ И БИОЭТАНОЛ

An analysis of literature data the following preprocessing methods starch, pentosane- and cellulosic feedstock for enzymatic hydrolysis polysaccharides: hydrothermal, organosolvent obtaining technical cellulose, organosolvent with sulfuric acid, acid-catalyzed steam explosion, alkali, bisulfite (SPORL) and acid-catalyzed using a disk mill is presented.Recommendations about improvement of technological schemes of obtaining fodder protein products of bran together with other grain waste are provided. Technological scheme should include additional process fine grinding of bran and grain waste and hydro-thermodynamic treatment (HTDO) at the next technological mode: a.d.s ≥ 15%; t = 86–100 °C; processing time ≤ 1 h; using a thermostable α-amylase (Zymajunt-340С* or Amylase HT-4000 or Amileks 4T). The effectiveness of a subsequent enzymatic hydrolysis of partially decomposed starch and non-starch polysaccharides of starchy raw material is ensured by the enzymatic Начало формыКонец формыcomplex including Glucoamylase, GC 220, containing cellulase, cellobiase, xylanase and β-glucanase activities, and Novozymes 188, containing cellobiase.The most effective methods for preprocessing of pentosan - and cellulosic feedstock to enzymatic hydrolysis of cellulose in a 2% suspension of lignocellulosic residue are allow obtained an overall yield of sugars and ethanol at least 90% of the theoretical. The following preprocessing methods are considered to be as the most promising: organosolvent with H2SO4 and steam explosion with SO2 and the subsequent washing of the extruded biomass with water and oxidation-alkaline solution and mechanochemical: bisulfite (SPORL) and acid catalysis units with installation of hot grinding (IHG). It is established, that in the first two methods allowed the lignin content in the lignocellulose is to 16-18%, and the third up to 30%. Acid-catalyzed hydrolysis method with elements of SPORL technology with the use of installation hot grinding (IHG) is recommended for laboratory and experimental-industrial tests in the hydrolysis industry.Cellulose from lignocellulosic residue is efficiently hydrolysed by Сelluclast (20 FPU/g glucan), and Novozyme 188 (β-glucosidase : cellulase 1,75–2,0 : 1) or Spezyme CP, GC-220 (15 FPU/g glucan), Multifect Xylanase (β-glucosidase:cellulase 2,0 : 1).

Efficient co-displaying and artificial ratio control of α-amylase and glucoamylase on the yeast cell surface by using combinations of different anchoring domains.

Recombinant yeast strains that display heterologous amylolytic enzymes on their cell surface via the glycosylphosphatidylinositol (GPI)-anchoring system are considered as promising biocatalysts for direct ethanol production from starchy materials. For the effective hydrolysis of these materials, the ratio optimization of multienzyme activity displayed on the cell surface is important. In this study, we have presented a ratio control system of multienzymes displayed on the yeast cell surface by using different GPI-anchoring domains. The novel gene cassettes for the cell-surface display of Streptococcus bovis α-amylase and Rhizopus oryzae glucoamylase were constructed using the Saccharomyces cerevisiae SED1 promoter and two different GPI-anchoring regions derived from Saccharomyces cerevisiae SED1 or SAG1. These gene cassettes were integrated into the Saccharomyces cerevisiae genome in different combinations. Then, the cell-surface α-amylase and glucoamylase activities and ethanol productivity of these recombinant strains were evaluated. The combinations of the gene cassettes of these enzymes affected the ratio of cell-surface α-amylase and glucoamylase activities and ethanol productivity of the recombinant strains. The highest ethanol productivity from raw starch was achieved by the strain harboring one α-amylase gene cassette carrying the SED1-anchoring region and two glucoamylase gene cassettes carrying the SED1-anchoring region (BY-AASS/GASS/GASS). This strain yielded 22.5 ± 0.6g/L of ethanol from 100g/L of raw starch in 120h of fermentation.

Phenotypic characterisation of Saccharomyces spp. for tolerance to 1-butanol.

Biofuels are expected to play a role in replacing crude oil as a liquid transportation fuel, and research into butanol has highlighted the importance of this alcohol as a fuel. Butanol has a higher energy density than ethanol, butanol-gasoline blends do not separate in the presence of water, and butanol is miscible with gasoline (Szulczyk, Int J Energy Environ 1(1):2876-2895, 40). Saccharomyces cerevisiae has been used as a fermentative organism in the biofuel industry producing ethanol from glucose derived from starchy plant material; however, it typically cannot tolerate butanol concentrations greater than 2 % (Luong, Biotechnol Bioeng 29 (2):242-248, 27). 90 Saccharomyces spp. strains were screened for tolerance to 1-butanol via a phenotypic microarray assay and we observed significant variation in response with the most tolerant strains (S. cerevisiae DBVPG1788, S. cerevisiae DBVPG6044 and S. cerevisiae YPS128) exhibiting tolerance to 4 % 1-butanol compared with S. uvarum and S. castelli strains, which were sensitive to 3 % 1-butanol. Response to butanol was confirmed using traditional yeast methodologies such as growth; it was observed that fermentations in the presence of butanol, when using strains with a tolerant background, were significantly faster. Assessing for genetic rationale for tolerance, it was observed that 1-butanol-tolerant strains, when compared with 1-butanol-sensitive strains, had an up-regulation of RPN4, a transcription factor which regulates proteasome genes. Analysing for the importance of RPN4, we observed that a Δrpn4 strain displayed a reduced rate of fermentation in the presence of 1-butanol when compared with the BY4741 background strain. This data will aid the development of breeding programmes to produce better strains for future bio-butanol production.

Wet-milling of buckwheat with hull and dehulled – The properties of the obtained starch fraction

The buckwheat with or without hull were used for the laboratory wet-milling. Starchy materials obtained was characterised by determining starch extraction efficiency, particle size distribution and microstructure. The pasting (RVA) and thermal properties (DSC) were also analysed. The starch extraction efficiency was higher for total starch isolated from buckwheat with hull compared to dehulled. The mean particle diameter of the pure starch isolated from both buckwheats was about 18 μm. The longer time of steeping of buckwheat with hull caused a decrease in temperature of gelatinization compared to the dehulled ones. Significantly higher enthalpy values for both pure starches compared to the other samples were noticed. The increasing of gelatinisation enthalpy with increasing of the steeping time and the higher protein amount was observed. The used wet-milling method did not change significantly the properties of the obtained starchy materials compared to raw material.

Physics-based modeling of simultaneous heat and mass transfer intensification during vacuum steaming processes of starchy material

Simultaneous heat and mass transfers in reactive porous media such as starchy material are important phenomena, which occur during hydrothermal processes. The driving force in this type of material is not governed only by the moisture potential gradient (non-equilibrium condensation rate) but also by a hydric need required to change phase (melting). In this paper we compared in simulation two processes at the temperature of 120°C. The first one is named the RP-HMT process for Reduced Pressurized-Heat Moisture Treatment. The second is the DV-HMT process for Direct Vapor-Heat Moisture Treatment. In the first process transfer phenomena are amplified due to the presence of an initial vacuum before injection of live steam into the reactor.A model of the processes is implemented and solved using COMSOL multiphysics software. We observed that heat transfer intensification during RP-HMT reduces the resistance of air, and consequently facilitates the diffusion of steam into the product. The computed values confirm those obtained experimentally. A study of the model sensibility to the parameters was investigated. The simulation results show also that the influences of the estimated parameters strongly depend on the hydrothermal processes. They are more important for the RP-HMT than for the DV-HMT.

Acetone–butanol–ethanol production by separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) methods using acorns and wood chips of Quercus acutissima as a carbon source

We investigated the production of acetone–butanol–ethanol (ABE) from acorns (starchy material) and wood chips (cellulosic material) of Quercus acutissima through separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) by Clostridium acetobutylicum NBRC13948. With acorns, 15.45g/L of ABE was obtained in 96h of fermentation time from the enzymatic hydrolyzate of acorns by SHF. From the SSF, it was found that ABE (16.70g/L, 120h) was produced without enzyme addition, given that C. acetobutylicum NBRC 13948 possesses an amylolytic enzyme. With wood chips, steam explosion was used for pretreatment. In the SHF, when the enzymatic hydrolyzate of residue of water and methanol extraction after pretreatment was used as the substrate, the maximum ABE concentration, 15.29g/L, was obtained in 120h. From the SSF, 13.41g/L of ABE was obtained in 144h, and it was determined that sufficient enzyme loading was 7.8mg of protein to 1g of dry substrate.

Influence of various yeast strains and selected starchy raw materials on production of higher alcohols during the alcoholic fermentation process

The formation of volatile by-products during alcoholic fermentation is affected by many factors such as the type of yeast strain applied, technological parameters of the process and the raw material used as the main constituent of the fermentation medium. The influence of availability of sugars released by the plant polysaccharide hydrolysis on the concentration of higher alcohols during the fermentation process was analyzed. Significant differences in the starch hydrolysis dynamics for various raw materials, entailing changes in availability of sugars such as glucose, maltose, maltotriose and maltotetraose, are reported. The highest glucose concentration after the mashing process (93.8 ± 3.8 mg cm−3) was observed for the maize mash (as compared to that of the rye and amaranth mashes, 24.9 ± 0.9 and 46.9 ± 2.5 mg cm−3, respectively). The highest glucose content in the maize mash resulted in a significantly higher isobutanol and 2-methyl-1-butanol content at the initial stage of fermentation, irrespective of the yeast strain used (D-2 or As-4). The highest final total content of fusel alcohols (ca. 5,460 mg dm−3 EtOH, on average) was also found in the distillates produced from the maize mash. However, the concentration of higher alcohols in the rye and amaranth distillates was similar and reached the level of ca. 3,440 mg dm−3 EtOH, on average. It is shown that the polysaccharide hydrolysis rate, and hence the rate at which fermenting sugars are released, significantly affects the concentration of higher alcohols in the produced distillates.

Determination of total iodine in French Polynesian foods: Method validation and occurrence data

Pacific Island populations show some of the highest incidences of thyroid cancer in the world, and iodine deficiency is suspected to play a role. Iodine content was determined in 124 different French Polynesian food samples using inductively coupled plasma-mass spectrometry after alkaline digestion. For samples containing starch, the method was optimised by including an additional enzymatic treatment step. This analytical method was validated with an accuracy profile approach, using certified reference materials with iodine contents ranging from 0.027 to 4.95mgiodinekg−1 dry weight. The trueness bias ranged from −5.8% to 22.4% and the highest observed intermediate precision coefficient of variation CVR was 11% in starchy materials. Tested Polynesian foods showed large variation in iodine content, with values of 0.014–0.032mgkg−1 for fruits, 0.014–0.081mgkg−1 for starchy samples, 0.027–1.85mgkg−1 for green vegetables, 0.222–5.19mgkg−1 for fish, 6.51–85.6mgkg−1 for shellfish, and 0.004–1.39mgkg−1 for beverages.