Cassava Hydrolysate Research Articles

Toxicological safety assessment of provitamin A cassava hydrolysate with free and encapsulated Lacticaseibacillus rhamnosus GG in the Wistar rat model

Expanding the non-dairy food and beverage matrices useful as carriers for probiotics such as Lacticaseibacillus rhamnosus GG is an ongoing concern. This has led to the development of provitamin A cassava (PAC) hydrolysate. However, the safety of novel food matrices such as PAC hydrolysate, a non-dairy probiotic beverage, needs to be assessed. The acute and 30-day sub-chronic toxicological effects of the oral administration (using oral gavage) of PAC hydrolysate without or with free or encapsulated L. rhamnosus GG, were evaluated in the Wistar rat model.No treatment-related acute toxicity, and no changes of toxicological significance (p > 0.05) in the relative organ weights, haematological or biochemical parameters were observed in all the PAC-administered Wistar rats, compared to the control. Therefore, oral administration of provitamin A cassava hydrolysate without or with free or encapsulated L. rhamnosus GG showed evidence of safety when consumed at the doses recommended in this study and not more than 30 days.

Bioethanol production from cassava fermentation in pervaporation membrane bioreactor fed with high concentration sugar

Bioethanol production from cassava in a pervaporation membrane bioreactor consisted of fermentation coupled with polydimethylsiloxane (PDMS) membrane separation has been carried out. A cassava hydrolysate with a high sugar concentration of 448–492 gL-1 was prepared by repeating the liquefaction process and then fed to the bioreactor to overcome the fermentation broth volume expansion problem. The coupled system lasted as long as 248 h. The cell concentration, sugar consumption rate, ethanol productivity, and total ethanol production were 22 gL-1, 3.91 gL-1h−1, 1.47 gL-1h−1, and 365.1 gL-1, respectively. The average membrane flux and separation factors of the membrane were 645 gm-2h−1 and 5.3, respectively. A permeate vapor with as high as 21.5 wt% ethanol concentration downstream of the membrane was obtained. Fractional condensation was used downstream of the membrane to differentially refine and recover the ethanol from the permeate vapor. The ethanol concentration can be increased by 57.3 % with the fractional condensation method, with separation factor increased to 9.8–14.9. As much as 96.6 % of the permeated ethanol on the downstream of the membrane can be recovered as the product with high ethanol concentration.

Phenolic, flavonoid, and β-carotene contents of provitamin A cassava hydrolysate with free and encapsulated Lactobacillus rhamnosus GG improves antioxidant biomarkers in kidney, heart and liver of Wistar rats.

In vitro antioxidant activity and possible in vivo antioxidative effects of provitamin A cassava hydrolysate inoculated with free or encapsulated Lactobacillus rhamnosus GG (LGG), a ready-to-drink probiotic beverage containing natural β-carotene and other phytochemicals, were evaluated. Provitamin A cassava was orally administered to male Wistar rats (n=40, 120-150g) for 30 days. Regression analysis showed the phenolic and total flavonoid contents of provitamin A cassava hydrolysate contributed 68% and 95%, respectively, to the antioxidant activity (by 1,1-diphenyl-2-picrylhydrazyl assay) (83.3±1.8-87±1.8%). in vivo study showed that malondialdehyde and superoxide dismutase activities were lowered or unchanged with a significant increase in antioxidant biomarkers (reduced glutathione, glutathione-S-transferase, and glutathione peroxidase) in the kidney, heart, and liver of all rats administered provitamin A cassava hydrolysate with LGG, especially at doses 2×1010 CFU, compared to control. Provitamin A cassava hydrolysate with LGG showed significant antioxidant activity In vitro and in vivo, thus indicating its potential usefulness in the food industry as an antioxidant beverage. PRACTICAL APPLICATION: This study reports the antioxidant properties of provitamin A cassava hydrolysate, which can be consumed as a refreshing beverage while also delivering antioxidant benefits. In the food and beverage industry, provitamin A cassava hydrolysate could be applied as a nutraceutical beverage with therapeutic functions. This product innovation increases the value-addition of cassava and expands the nondairy food matrix options used as probiotic carriers.

Efficient poly(β-L-malic acid) production from cassava hydrolysate by cell recycle of Aureobasidium pullulans.

Poly(β-L-malic acid) (PMLA) is a water-soluble, biodegradable, and biocompatible polymer with broad prospective applications and can be hydrolyzed to produce widely used acidulant L-malic acid. In order to meet an increasing demand of PMLA, we employed two effective cell-recycling strategies to produce PMLA from raw cassava hydrolysate by Aureobasidium pullulans ZD-3d. In fed-batch fermentation with raw cassava hydrolysate, 101.9g/L PMLA was obtained with the productivity and yield of 0.77g/L/h and 0.40g/g, respectively. Further, three times of membrane filtration-based cell recycling fermentation was carried out, with a high productivity and yield of 1.04-1.64g/L/h and 0.5-0.84g/g achieved, respectively. While harnessing centrifugation-based cell recycling fermentation for five times, the productivity and yield approached 0.98-1.76g/L/h and 0.78-0.86g/g, respectively. To our knowledge, the processes showed the highest average PMLA productivity compared with others using low-cost biomass, which offered efficient and economical alternatives for PMLA production. KEY POINTS: • PMLA production from raw cassava hydrolysate by Aureobasidium pullulans was studied • High PMLA productivity and yield were obtained via two cell recycling strategies • The highest average PMLA productivity from low-cost biomass to date was achieved.

Provitamin A cassava hydrolysate with Lactobacillus rhamnosus GG regulates weight gain, lipids and postprandial glycemia in wistar rats and humans

PurposeThis study aims to evaluate the effect of probiotic provitamin A cassava hydrolysate with Lactobacillus rhamnosus GG (hLGG) on weight and lipid profile of Wistar rats and its glycemic index using Wistar rats and human subjects.Design/methodology/approachAdult male Wistar rats (n = 40, 120–150 g) were orally administered provitamin A cassava hydrolysate with 1 × 1010, 2 × 1010 and 4 × 1010 CFU/g encapsulated or CFU/mL free Lactobacillus rhamnosus GG for 30 days, during which weight and lipid profile of rats were monitored. Blood glucose levels of rats and human subjects were also measured in Oral Glucose Tolerance Test to determine the Glycemic indices of hLGG.FindingsRats administered the highest doses of free or encapsulated hLGG [(4 × 1010 CFU) (PHE4 and PHF4, respectively)] had the lowest (18.2 ± 0.7 and 8.0 ± 0.6%, respectively, p < 0.001) percentage body weight gain compared to control (40 ± 0.6%). Lowest cholesterol and triglyceride (42.4 ± 0.5 and 44.4 ± 0.7 g/dL, p < 0.001, respectively) were observed in rats administered PHE4, with the lowest plasma glucose concentrations in PHE4 and PHF4 groups (43 ± 1 and 49 ± 0.7 g/dL, p < 0.001, respectively). Oral Glucose Tolerance Test for rats and human subjects showed lower peak blood glucose levels and glycemic indices in hLGG groups compared to controls in a dose-dependent manner.Originality/valueConsumption of soft drinks, which supply non-nutritive energy, may lead to degenerative metabolic disorders such as obesity and diabetes. Beverages with probiotics such as Lactobacillus rhamnosus GG, on the other hand, offer a positive weight management approach. Development of non-dairy beverages such as provitamin A cassava hLGG is ongoing. Provitamin A cassava hLGG showed its ability to control weight gain, blood glucose levels and serum lipids. Thus, the beverage can be consumed as a healthy alternative to soft drinks and for weight management.

Viability of Lactobacillus rhamnosus GG in provitamin A cassava hydrolysate during fermentation, storage, in vitro and in vivo gastrointestinal conditions

The effect of alginate encapsulation on the viability of Lactobacillus rhamnosus GG in provitamin A cassava hydrolysate used as a carrier during processing, storage, invitro and invivo gastro-intestinal conditions was assessed. Several studies in the literature have reported the viability of probiotics in non-dairy food matrices such as fruits and vegetables. However, there is need for further studies exploring the maintenance of probiotics in other non-dairy options and to evaluate the resistance of probiotics during passage through the gastro-intestinal tract. Lactobacillus rhamnosus GG (LGG) cells were microencapsulated in alginate beads (using emulsion and extrusion techniques), characterized and inoculated into provitamin A cassava starch hydrolysate. The survival/viability rates of LGG in provitamin A hydrolysate during storage (4 °C, 90 days), also in gastric and intestinal conditions (invitro and invivo) were measured. Free LGG cells in provitamin A cassava hydrolysates decreased rapidly in viability within the first 30 days of storage whereas encapsulated cells showed a gradual but insignificant decrease in viability. LGG cells maintained viability above 5 Log CFU/mL in hydrolysates with free LGG, and above 7 Log CFU/g in hydrolysates with encapsulated LGG by the end of 60 days of storage. Encapsulated LGG had 77.4 and 8.5% survival after 120 min in simulated gastric and intestinal juices, respectively. Growth direction index expanded up to 1.66 for LGG but decreased below −0.05 for total aerobes and Enterobacteriaceae in faeces of rats administered hydrolysate with encapsulated or free LGG by day 30. Encapsulated LGG showed better resistance during transit through gastrointestinal conditions.

Efficient two-step lactic acid production from cassava biomass using thermostable enzyme cocktail and lactic acid bacteria: insights from hydrolysis optimization and proteomics analysis.

Lactic acid is an intermediate-volume specialty chemical, used in the production of biodegradable polymers and other chemicals. Although lactic acid production process is well established, however, the cost of production is very high. Therefore, in this study; starchy biomass (cassava) was hydrolyzed with in-house enzyme cocktail prepared from Aspergillus foetidus MTCC508 and Bacillus subtilis RA10. Process optimization using Taguchi experimental design helped to optimize the most effective ratio of fungal and bacterial amylase for effective saccharification of cassava. A higher sugar yield of 379.63mg/gds was obtained under optimized conditions, using 30U/gds of bacterial enzyme and 90U/gds of the fungal enzyme at pH 4 within 48h of saccharification. Among 11 lactic acid bacteria isolated, Lactobacillus fermentum S1A and Lactobacillus farraginis SS3A produced the highest amount of lactic acid 0.81g/g and 0.77g/g, respectively, from the cassava hydrolysate. The study proved the potential renewable source of cassava biomass as a source for fermentable sugars that can be fermented to lactic acid with high yield. In future, this cost-effective and environmental-friendly bioprocess can be upscaled for industrial lactic acid production.

Provitamin A Cassava Hydrolysate with Lactobacillus rhamnosus Gg Improves Serum Lipid Profile in Wistar Rats

Abstract Objectives There is considerable interest in the development of high quality food products and dietary supplements that help in weight management. Drug intervention could have a negative side effect. Consumption of probiotics such as Lactobacillus rhamnosus GG cells through food products could offer a positive approach to weight management. Thus, probiotic beverages could serve as a healthy alternative in weight management. The objective of this study is to determine the effect of probiotic beverage such as provitamin A cassava hydrolysate carrying Lactobacillus rhamnosus GG in weight management. Methods Provitamin A cassava hydrolysate was inoculated with free (PHF) or alginate-encapsulated (PHE) Lactobacillus rhamnosus GG (LGG) cells in doses 1, 2 or 4 × 1010 CFU/ml, and administered orally to adult Wistar rats (120–150 g, n = 40 males, 8 groups). All rats were dosed orally once daily for 4 weeks, recording weekly body weight changes as percentage change, and compared against Control (distilled water). Serum lipid profile (total cholesterol, triglycerides and high density lipoprotein) were determined after sacrificing the rats. Data were analyzed using descriptive statistics and ANOVA at α0.05. Results The body weight gain in control rats was significantly higher (α0.05) by the end of the 4th week (40.00%) than PHF or PHE groups at doses 1, 2 or 4 × 1010 CFU/ml (34.59, 24.38 and 8.04%, or 30.34, 23.49 and 18.24% respectively) which reduced with increasing doses. Total cholesterol, triglycerides and high density lipoprotein were higher in control rats (65.40, 56.60 and 29.48 mg/dL respectively) than in PHF or PHE groups at dose 4 × 1010 CFU/ml (54.60, 44.40 and 27.48 mg/dL, and 62.40, 46.60 and 23.12 mg/dL respectively). Conclusions Provitamin A cassava hydrolysate with L. rhamnosus GG was able to induce a transient weight reduction in rats, owing to its potential in reducing serum cholesterol and exerting anti-obesity effect. Thus it could be consumed as a beverage targeting weight management. Funding Sources Self.

Production of 2,3-butanediol from glucose and cassava hydrolysates by metabolically engineered industrial polyploid Saccharomyces cerevisiae

Background2,3-Butanediol (2,3-BDO) is a valuable chemical for industrial applications. Bacteria can produce 2,3-BDO with a high productivity, though most of their classification as pathogens makes them undesirable for the industrial-scale production. Though Saccharomyces cerevisiae (GRAS microorganism) was engineered to produce 2,3-BDO efficiently in the previous studies, their 2,3-BDO productivity, yield, and titer were still uncompetitive compared to those of bacteria production. Thus, we propose an industrial polyploid S. cerevisiae as a host for efficient production of 2,3-BDO with high growth rate, rapid sugar consumption rate, and resistance to harsh conditions. Genetic manipulation tools for polyploid yeast had been limited; therefore, we engineered an industrial polyploid S. cerevisiae strain based on the CRISPR-Cas9 genome-editing system to produce 2,3-BDO instead of ethanol.ResultsEndogenous genes coding for pyruvate decarboxylase and alcohol dehydrogenase were partially disrupted to prevent declined growth rate and C2-compound limitation. A bacterial 2,3-BDO-producing pathway was also introduced in engineered polyploid S. cerevisiae. A fatal redox imbalance was controlled through the heterologous NADH oxidase from Lactococcus lactis during the 2,3-BDO production. The resulting strain (YG01_SDBN) still retained the beneficial traits as polyploid strains for the large-scale fermentation. The combination of partially disrupted PDC (pyruvate decarboxylase) and ADH (alcohol dehydrogenase) did not cause the severe growth defects typically found in all pdc- or adh-deficient yeast. The YG01_SDBN strain produced 178 g/L of 2,3-BDO from glucose with an impressive productivity (2.64 g/L h). When a cassava hydrolysate was used as a sole carbon source, this strain produced 132 g/L of 2,3-BDO with a productivity of 1.92 g/L h.ConclusionsThe microbial production of 2,3-BDO has been limited to bacteria and haploid laboratorial S. cerevisiae strains. This study suggests that an industrial polyploid S. cerevisiae (YG01_SDBN) can produce high concentration of 2,3-BDO with various advantages. Integration of metabolic engineering of the industrial yeast at the gene level with optimization of fed-batch fermentation at the process scale resulted in a remarkable achievement of 2,3-BDO production at 178 g/L of 2,3-BDO concentration and 2.64 g/L h of productivity. Furthermore, this strain could make a bioconversion of a cassava hydrolysate to 2,3-BDO with economic and environmental benefits. The engineered industrial polyploid strain could be applicable to production of biofuels and biochemicals in large-scale fermentations particularly when using modified CRISPR-Cas9 tools.

Optimization Method for Bioethanol Production from Giant Cassava (&lt;i&gt;Manihot esculenta&lt;/i&gt; var. Gajah) Originated from East Kalimantan

Here is the first report of bioethanol production from giant cassava, a variety of cassava originated from East Kalimantan. Hydrolysis on freshly grated cassava with two different acids was studied separately. The experiment was conducted as a single factor experiment in Completely Randomized Design (CRD) with five treatments (0.0–1.0 M of acid solution), each replicated three times. Reducing sugars, unhydrolyzed substance (fibers), and hydrolysate clarity was determined. The experiment was continued by studying fermentation condition using factorial experiment (2 x 4) in CRD. The first factor was starter concentration (Saccharomyces cerevisiae, 5 and 10%) and the second factor was fermentation time (2–11 days). Biomass and alcohol content in fermentate were determined. The data were analyzed by ANOVA, excluding alcohol content that analyzed by the non-parametric statistic. Optimization using regression analysis showed that hydrolysis by HCl was more effective than H2SO4. Hydrolysis solution of 0.58 M HCl gave an optimum reducing sugar in hydrolysate (5.6%), which equivalent to a yield of 28.18%. Starter concentration affected significantly on biomass and alcohol content (p &lt; 0.001) of fermentate, while fermentation time affected significantly only on alcohol content (p &lt; 0.001). Optimum condition of cassava hydrolysate fermentation (100 mL) was using 5% yeast for 8 days, which gave a yield of 14.17% bioethanol.

KONSISTENSI PRODUKSI NATA DALAM MEDIA FERMENTASI YANG MENGANDUNG HIDROLISAT UBI KAYU

Nata de coco is known as a gelatinous substance, white to creamy-yellow, firm, glossy and not sticky, produced by some bacteria, which forms on the surface of coconut water medium during fermentation. Acetobacter xylinum (current name: Gluconacetobacter xylinus ) is the common bacteria which synthesized nata de coco. Besides coconut water, there are some alternatives for making nata, such as cassava. Gluconacetobacter sp. was employed in this study to produce nata de coco from cassava hydrolysate medium (U) and compared it qualitatively and quantitatively to coconut water medium (K). In U medium, glucose was the main product derived from hydrolysis of cassava. Fermentation was conducted three times with each former fermentations became sources of inocula for the next fermentations, respectively. All data were analysed with IBM SPSS Statistics 23. Fermentation product of nata from U medium were relatively stable in thickness, wet weight, dry weight, yield, water content, and log from total bacteria (quantitative) and in colour, texture, transparency, and surface of nata (qualitative). Glucose was rapidly consumed by bacteria then other sugar (fructose and sucrose). Glucose consumption and nata yield was affected by the number of bacteria. However, nata yield was not significantly influenced by glucose consumption. Nata yield was possibly influenced by other factors such as nutrient content in U medium. Growth dynamics of Gluconacetobacter sp. was measured in log cfu mL -1 on Hassid-Barker Agar (HBA) medium and relative number of 16S rRNA genes . Bacterial growth during fermentation in U medium were relatively more stable than fermentation on K medium although the yield in K medium gradually increased and were higher than U medium. Keywords: cassava hydrolysate, Gluconacetobacter sp., nata, stable fermentation

KEPADATAN DAN LAJU PERTUMBUHAN SPESIFIK Nannochloropsis sp. PADA KULTIVASI HETEROTROPIK MENGGUNAKAN MEDIA HIDROLISAT SINGKONG

Growth of Nannochloropsis sp. was observed in laboratory cultivation condition with enrichment of cassava hydrolysate into culture medium as follow : 25 ml microalgae strain, 75 ml seawater, without cassava hydrolysate (A); 25 ml microalgae strain, 25 ml cassava hydrolysate, 50 ml seawater (B), 25 ml microalgae strain, 50 ml cassava hydrolysate, 25 ml seawater (C). Cultivation condition was fixed as follow temperature 29°C, seawater pH 8, and salinity 30 ‰. Microalgae cultivation was performed at microalgae laboratory of Surfactant and Bioenergy Research Center using 100 ml Erlenmeyer covered by black plastic to prevent the influence of light. The specific growth rate of Nannochloropsis sp. was observed in 7 days for different cultivation medium composition. The highest density of microalgae was in the 4th days with 50ml cassava hydrolysate’s feeding (C treatment) about 172.661 cell/mL. The highest specific growth rate for Nannochloropsis sp. cultivation was observed in the 6th days without cassava hydrolysate’s feeding. Result of statistical analysis showed that different cassava hydrolysate’s feeding treatments (ml) in heterotrophically microalgae cultivation influenced the density of microalgae (cell/mL) but not influenced the specific growth rate of microalgae (per day).Keywords: Cassava hydrolysate, Density, Heterotrophic cultivation, Spesific growth rate, Nannochloropsis sp.

Long-Term Production of Fuel Ethanol by Immobilized Yeast in Repeated-Batch Simultaneous Saccharification and Fermentation of Cassava

In this study, a fibrous matrix with chemical modification was used as a support material for the immobilization of Saccharomyces cerevisiae 1308. Cassava hydrolysate without filteration was used for ethanol fermentation. An average utilization rate of starch of 83.5% was obtained by the immobilized cells during the first seven repeated simultaneous saccharification and fermentation. The utilization rate of starch of the immobilized cells was 2.1% higher than that of free cells with an inoculation quantity of 15% (v/v) under the same fermentation conditions. In addition, the effects of enzyme feeding strategies on immobilized yeast fermentation were investigated. The highest utilization rate of starch of 85.9% was obtained at 35 °C with the optimal enzyme feeding strategy. Fermentation performed successfully for about 6 months with 87 batches suggests that ethanol production from cassava using immobilized yeast in a fibrous-bed bioreactor is feasible and may meet the demands of industrial production.

High-productivity lipid production using mixed trophic state cultivation of Auxenochlorella (Chlorella) protothecoides.

A mixed trophic state production process for algal lipids for use as feedstock for renewable biofuel production was developed and deployed at subpilot scale using a green microalga, Auxenochlorella (Chlorella) protothecoides. The process is composed of two separate stages: (1) the photoautotrophic stage, focused on biomass production in open ponds, and (2) the heterotrophic stage focused on lipid production and accumulation in aerobic bioreactors using fixed carbon substrates (e.g., sugar). The process achieved biomass and lipid productivities of 0.5 and 0.27 g/L/h that were, respectively, over 250 and 670 times higher than those obtained from the photoautotrophic cultivation stage. The biomass oil content (over 60% w/DCW) following the two-stage process was predominantly monounsaturated fatty acids (~82%) and largely free of contaminating pigments that is more suitable for biodiesel production than photosynthetically generated lipid. Similar process performances were obtained using cassava hydrolysate as an alternative feedstock to glucose.

Comparison of Ethanol Fermentation Properties between Laboratorial and Industrial Yeast Strains using Cassava Hydrolysate

In order to investigate the ethanol fermentation properties of alcohol yeasts a laboratorial strain (CEN.PK2-1D) and two industrial alcohol yeasts (JHS100 and JHS200) of Saccharomyces cerevisiae were cultured in a pure YP medium with 300 g/L glucose and cassava hydrolysate. Spot assay and cell viability tests showed that both the JHS100 and JHS200 strains exhibited higher ethanol tolerance than the CEN.PK2-1D strain. The JHS100 strain demonstrated the highest cell growth, glucose consumption and ethanol production. In particular, an anaerobic batch fermentation of the JHS100 strain using cassava hydrolysate with 250 g/L glucose resulted in a 106.1 g/L ethanol concentration, 0.42 g/g ethanol yield and 3.15 g/L-hr ethanol productivity, which were 53%, 13%, 53% higher than the corresponding values for the CEN.PK2-1D strain. By changing the pure YP medium to cassava hydrolysate, 19% and 17% decreases in ethanol yield and productivity for the CEN.PK2-1D strain were observed, whereas the cultures of the JHS100 and JHS200 stains showed similar ethanol productivities and only an 8% decrease in ethanol yield. Furthermore, the JHS100 and JHS200 stains produced lower levels of glycerol and acetate byproducts than the CEN.PK2-1D strain. Consequently, the outstanding ethanol fermentation performance of the industrial strains might be owing to rapid cell growth, high ethanol tolerance, low nitrogen requirements and the low formation of by-products.

Biodiesel production from algal oil using cassava (Manihot esculenta Crantz) as feedstock

As a potential source of biomass supplies, cassava (Manihot esculenta Crantz) has been studied for bioethanol production, but not for the production of biodiesel. In this study, we used cassava hydrolysate as an alternative carbon source for the growth of microalgae (Chlorella protothecoides) which accumulated oil in vivo, with high oil content up to 53% by dry mass under a 5-L scale fermentation condition. The oils were extracted and converted into biodiesel by transesterification. The biodiesel obtained consisted of mainly unsaturated fatty acids methyl ester (over 82%), cetane acid methyl ester, linoleic acid methyl ester, and oleic acid methyl ester. This work suggests the feasibility of an alternative choice for producing biodiesel from cassava by microalgae fermentation. We report herewith the optimized condition for the fermentation and for the hydrolysis of cassava as the carbon source.

DO-stat fed-batch production of 2-keto-d-gluconic acid from cassava using immobilized Pseudomonas aeruginosa

Bioconversion of cassava-derived glucose to 2-keto-D-gluconic acid (2-KDG) using resting cells of immobilized Pseudomonas aeruginosa IFO 3448 was investigated. The tuberous roots of cassava were selected as the feedstock as they are inexpensive and widely available, and possess high amounts of starch (approximately 70% (w/w) of dry mass). Immobilized bacteria was used in a fed-batch fermenter and recycled over a period of 2 weeks. Given that the formation of 2-KDG from glucose requires oxygen as a reagent, and that high glucose concentrations are detrimental to the production yield of 2-KDG by resting cells, a DO-stat control strategy was used, whereby the feed rate of cassava hydrolysate was regulated by coupling it with the control variable, dissolved oxygen. For 319 h of operation including three cycles of repeated fed batch, 72 g of 2-KDG was produced from hydrolysate derived from 110 g of dried cassava at a maximum production rate of 0.55 g/L/h and an average concentration of 35 g/L.

Culture of Saccharomyces cerevisiae on hydrolyzed waste cassava starch for production of baking-quality yeast

A fermentation medium based on waste cassava starch hydrolysate and a four-phase feeding strategy for a fed-batch culture of Baker's yeast Saccharomyces cerevisiae are presented. Cassava starch isolated from the wastewater produced in processing of cassava mash into gari was liquefied with a thermostable 1.4-α- d-glucanohydrolase (EC 3.2.1.1) in the presence of 100 ppm Ca 2+ at 80°C and pH 6.1–6.3 for one h. The liquefied material was saccharified with 1.4-α- d-glucan glucohydrolase (EC 3.2.1.3) at 55°C and pH 5.5 for two h. Over 98% of the starch was hydrolyzed; about 80.7% of the hydrolysate was glucose. The fermentation feeding profile which was based on a desired specific growth rare range of 0.18–0.23 h −1, a biomass yield coefficient of 0.5 g g −1, and a feed substrate concentration of 200 g l −1 was implemented manually using the cassava hydrolysate feed in test experiments and glucose feed in control experiments. The fermentation off-gas was analyzed on-line by mass spectrometry for the calculation of the oxygen uptake rate, the carbon dioxide evolution rate, and the respiratory quotient. Off-line determinations of biomass, ethanol, and glucose were done, respectively, by dry weight, gas chromatography, and spectrophotometry. Cell mass concentrations of 50–58 g l −1 were achieved in all experiments within 28 h of which the last 15 h were in the fed-batch mode. The average biomass yields for the cassava and glucose media were identical at 0.49 g g −1. No significant differences were observed between the leavening activities of the products of the test, the control media, and a commerical preparation of instant active dry yeast. Waste cassava starch hydrolysate was established as a suitable low cost replacement for glucose in the production of baking-quality yeast.

Saccharification of cassava (manihot esculenta) with millet amylase

AbstractMillet amylase formed during malting was used for teh saccharification of cassava (Manihot esculenta) into glucose syrup. The resulting syrup was also fermented to ethanol and citric acid. The maximum α‐amylase activity occurred within 30 hours of millet germination at an optimum pH 8.0 and 40°C. The T. reesei enzymes enhanced the rate of cassava hydrolysis and paper chromatography revealed the presence of maltose, glucose and galactose in the cassava hydrolysate. The low cost of millet coupled with the fact that it is readily available makes it an economic source of amylase.

Extractability and functionality of protein from yeast cells grown on cassava hydrolysate

An extraction of protein from two strains of yeast, Candida tropicalis and C. utilis, grown by batch method on cassava hydrolysate was carried out by a combination of mechanical and mild chemical treatment yielding about 71% and 68% protein for C. tropicalis and C. utilis, respectively. The process resulted in about 75–80% reduction in the nucleic acid level of the freeze dried whole yeast cells of both organisms. The protein concentrates showed a good amino acid profile comparable to egg protein with methionine and tryptophan as the limiting amino acids. The functional characteristics of the two yeast proteins were studied and compared with soy protein concentrate. They showed functional properties possessing very good wettability, emulsion capacity and whippability but poor emulsion stability.