Cassava pomace-based biodegradable packaging materials: a review.

Starch-based biodegradable packaging materials are gaining popularity as an alternative to the adverse environmental effects caused by conventional packaging materials. Despite the fact that cassava can withstand harsh environmental conditions and convert a greater quantity of solar energy into carbohydrates, its postharvest shelf life is extremely short. The preparation of cassava starch is an important method for extending the storage life of cassava. When one ton of cassava is processed, approximately 900 kg of cassava pomace, also known as cassava bagasse and cassava pulp, are produced. Due to the high residual starch and fibre content, reinforced packaging materials made from cassava pomace predominate. In the present manuscript, many possible uses of cassava pomace in packaging materials are discussed.  Furthermore, the performance attributes of packing materials assume a crucial role in the evaluation of the quality of the respective materials. The manuscript discusses various performance characteristics of packaging materials derived from cassava pomace. The features discussed include water vapour permeability, moisture content, solubility, thickness, colour, light barrier properties, mechanical properties, FT-IR analysis, thermal stability, biodegradation, contact angle, and the presence of plasticizers. Though cassava starch film has become a favourable substitute for conventional packaging materials, commercialization is limited due to having drawbacks, and the current solutions are also catalogued in this review.

Investigation of critical properties of Cassava (Manihot esculenta) peel and bagasse as starch-rich fibrous agro-industrial wastes for biodegradable food packaging.

Cassava peel and bagasse are fibrous, starch-rich agro-industrial wastes, which cause severe environmental impacts upon their disposal. However, these can be raw materials for biodegradable food packaging. In this study, their morphological, chemical, thermal properties, crystalline phases, and chemical compositions were investigated, and potential utilisation as alternative biodegradable food packaging matrices has been assessed. Residual starches in cassava peel and bagasse were morphologically similar with that of commercial cassava starch, whereas potassium (8570 ± 56 mg/kg), and calcium (5300 ± 147 mg/kg) were highly abounded in peel and bagasse respectively. The major crystalline phase, α-amylose dihydrate, for cassava peel (97.1 (2) %) and bagasse (99.0 (3) %) point towards the presence of starch. Calcium and silicon reported to be in crystalline phases respectively, in the forms of quartz and whewellite. These beneficial characteristics suggested the potential valorisation of cassava peel and bagasse with special interest as matrices for biodegradable food packaging.

Investigation of Morphological, Chemical, and Thermal Properties of Biodegradable Food Packaging Films Synthesised by Direct Utilisation of Cassava (Monihot esculanta) Bagasse.

The utilisation of edible sources of starch such as corn, wheat, potato, and cassava has become the common approach to develop biodegradable food packaging. However, the future food security issue from the wide application of such edible starch sources has become a major concern. Consequently, exploring non-edible sources of starch for starch-based biodegradable food packaging and their property enhancement have become one of the common research interests. Although there has been a great potentials of synthesising biodegradable food packaging by direct utilisation of agro-industrial waste cassava bagasse, there have been very limited studies on this. In this context, the current study investigated the potential of developing biodegradable food packaging by directly using cassava bagasse as an alternative matrix. Two film-forming mixtures were prepared by incorporating glycerol (30% and 35%), powdered cassava bagasse and water. The films were hot-pressed at 60 °C, 100 °C, and 140 °C temperatures under 0.28 t pressure for 6 min. The best film-forming mixture and temperature combination was further tested with 0.42 t and 0.84 t pressures, followed by analysing their morphology, functional group availability and the thermal stability. Accordingly, application of 35% glycerol, with 100 °C, 0.42 t temperature and pressure, respectively, were found to be promising for film preparation. The absence of starch agglomerates in film surfaces with less defects suggested satisfactory dispersion and compatibility of starch granules and glycerol. The film prepared under 0.42 t exhibited slightly higher thermal stability. Synthesised prototypes of food packaging and the obtained characterisation results demonstrated the high feasibility of direct utilisation of cassava bagasse as an alternative, non-edible matrix to synthesise biodegradable food packaging.

Efficient production of ε-poly-L-lysine from cassava bagasse hydrolysate used as carbon source by Streptomyces albulus US3-18.

The production of ε-poly-L-lysine (ε-PL) from cassava bagasse hydrolysate (CBH) by Streptomyces albulus US3-18 was investigated in this study. With 30 g/L glucose from CBH, 1.30 g/L ε-PL and 10.68 g/L biomass were obtained in shake flask fermentation. Interestingly, the two values were increased by 14.0% and 21.5%, respectively, compared to the control (1.14 g/L and 8.79 g/L). Simultaneously, the activities of four key enzymes of ε-PL synthesis during CBH fermentation were enhanced to varying degrees. In batch fermentation of 5-L bioreactor, 3.39 g/L ε-PL and 10.17 g/L DCW were harvested with 40 g/L glucose from CBH. The combination of fed-batch fermentation with two-stage pH strategy significantly increased ε-PL titer and biomass to 37.41 g/L and 41.0 g/L, respectively. Moreover, eleven volatile components were detected in CBH by GC-MS, and 6-pentyl-α-pyrone (6PP) was first identified as the most abundant volatile ingredient. The results in CBH fermentation demonstrated that S. albulus US3-18 exhibited high tolerance to these volatile byproducts. Using ICP-MS, the calcium concentration in CBH was determined as 195.0 mg/(kg hydrolyzate), and cobalt, copper, lead, chromium, mercury and arsenic were not detected. By adding 0.05 g/L CaCl2 to M3G medium, ε-PL yield was improved by 28.0%, indicating calcium was one of the factors for the enhanced ε-PL production. The study provides a reference for the efficient production of ε-PL from low-cost agricultural residues.

Lean and obese microbiota: differences in in vitro fermentation of food-by-products.

The aim of the study was to investigate the potential prebiotic effects of food-by-products (cassava bagasse (n=3), orange bagasse (n=2) and passion fruit peel (n=3)) using an in vitro model simulating the proximal colon, and to assess possible differences in fermentation when using faecal microbiota from lean or obese people. Fermentation of the by-products was compared to a control medium and the prebiotic inulin. The effects of the by-products on the dynamics of the gut microbiota differed according to the type of microbiota, as well as the type of by-product used. Principal Coordinate Analysis of the microbiota showed evidence of a clear separate clustering of lean and obese microbiota before the addition of substrates, which disappeared after fermentation, and instead, distinct clusters due to primary carbohydrate composition of the by-products (starch, fructan and pectin) were present. This is evidence that the substrates drove the obese microbiota to a healthier profile, more similar to that of the lean microbiota. Cassava bagasses enriched the beneficial genus Bifidobacterium in the obese microbiota. The production of total SCFA by cassava bagasses by the obese microbiota was higher than for control medium and inulin. Orange bagasses stimulated the growth of the butyrate-producing genus Coprococcus. Passion fruit peels were poorly fermented and generated negligible amounts of intermediate metabolites, indicating slow fermentation. Nevertheless, passion fruit peel fermentation resulted in a microbiota with the highest diversity and evenness, a positive trait regarding host health. In conclusion, the use of food-by-products could be an important step to tackle obesity and decrease the waste of valuable food material and consequently environmental pollution. They are an inexpensive and non-invasive way to be used as a dietary intervention to improve health, as they were shown here to drive the composition of the obese microbiota to a healthier profile.

Potential use of cassava by-product as ruminant feed.

Cassava (Manihot esculenta Crantz) bagasse is the by-product from industry (BCI), generated during manufacturing of cassava flour; this material has significant amounts of carbohydrates consisting in a potential energy source for ruminants. We hypothesized that the inclusion of BCI in the diets may lead to fermentation parameters equivalent to those of conventional feedstuff such as tropical grasses or grains; therefore, we aimed to evaluate ruminal fermentation parameters of BCI in in vitro conditions. Three different substrates were prepared: 100% BCI (BCI diet), 100% tifton (Cynodon spp.) hay (CTL diet), and 50% tifton hay +50% BCI (THB diet). Ruminal fermentation parameters of these diets were evaluated in in vitro gas production assays. In a 24-h incubation, increased values for total gas production, organic matter degradability, and methane production were observed for BCId and THB as compared to CTL (p < 0.05), while neutral THB showed the highest value for neutral detergent fiber degradability (p < 0.05). Fermentation profile was evaluated in a 48-h assay: shorter lag time as well as increased gas production potential and fractional fermentation rate were observed for the BCId and THB as compared to CTL (p < 0.05). Our results suggested that by-product from cassava industry is a suitable feed for ruminant production, providing desirable in vitro ruminal fermentation performance and organic matter degradability.

Secretomic analysis of cheap enzymatic cocktails of Aspergillus niger LBM 134 grown on cassava bagasse and sugarcane bagasse.

Currently, agroindustrial wastes are little used for generating value-added products; hence, their use of these waste to produce enzymatic cocktails for the conversion of lignocellulosic biomass to fermentable sugars is a very interesting alternative in the second-generation bioethanol process. The Ascomycota fungus Aspergillus niger LBM 134 produces hydrolytic enzymes in large proportions. In this work, A. niger LBM 134 was grown on sugarcane and cassava bagasses under optimized conditions. To identify the extracellular enzymes involved in the degradation of these agroindustrial wastes, the secretomes of the culture supernatants of the fungus were analyzed and validated by biochemical assays of the enzymatic activities. A. niger LBM 134 secreted higher quantities of xylanases and accessory hemicellulases when it grew on sugarcane bagasse, whereas more cellulases, amylases, and pectinases were secreted when it grew on cassava bagasse. These findings suggest two promising enzyme cocktails for the hydrolysis of lignocellulose carbohydrate polymers to fermentable sugars. These bioinformatic analysis were functional validates through enzymatic biochemical assays that confirm the biotechnological potential of A. niger LBM 134 for the bioconversion of hemicellulosic substrates such as sugarcane and cassava bagasses.

Efficient bioproduction of 5-aminolevulinic acid, a promising biostimulant and nutrient, from renewable bioresources by engineered Corynebacterium glutamicum.

BACKGROUND: 5-Aminolevulinic acid (5-ALA) is a promising biostimulant, feed nutrient, and photodynamic drug with wide applications in modern agriculture and therapy. Considering the complexity and low yield of chemical synthesis methods, bioproduction of 5-ALA has drawn intensive attention recently. However, the present bioproduction processes use refined glucose as the main carbon source and the production level still needs further enhancement. RESULTS: To lay a solid technological foundation for large-scale commercialized bioproduction of 5-ALA, an industrial workhorse Corynebacterium glutamicum was metabolically engineered for high-level 5-ALA biosynthesis from cheap renewable bioresources. After evaluation of 5-ALA synthetases from different sources, the 5-ALA biosynthetic pathway and anaplerotic pathway were rebalanced by regulating intracellular activities of 5-ALA synthetase and phosphoenolpyruvate carboxylase. The engineered biocatalyst produced 5.5 g/L 5-ALA in shake flasks and 16.3 g/L in 5-L bioreactors with a one-step fermentation process from glucose. To lower the cost of feedstock, cheap raw materials were used to replace glucose. Enzymatically hydrolyzed cassava bagasse was proven to be a perfect alternative to refined sugars since the final 5-ALA titer further increased to 18.5 g/L. Use of corn starch hydrolysate resulted in a similar 5-ALA production level (16.0 g/L) with glucose, whereas use of beet molasses caused seriously inhibition. The results obtained here represent a new record of 5-ALA bioproduction. It is estimated that replacing glucose with cassava bagasse will reduce the carbon source cost by 90.1%. CONCLUSIONS: The high-level biosynthesis of 5-ALA from cheap bioresources will brighten the prospects for industrialization of this sustainable and environment-friendly process. The strategy for balancing metabolic flux developed in this study can also be used for improving the bioproduction of other value-added chemicals.

Cassava starch films reinforced with lignocellulose nanofibers from cassava bagasse.

Cassava bagasse, a high-fiber coproduct of cassava starch processing, was used to produce lignocellulose nanofibers (LCNF) to apply as reinforcement in cassava starch films. LCNF-reinforced cast starch films were evaluated for changes in structural, thermal and mechanical properties and compared with control films reinforced with commercial grade nanoclay (Nclay). Five different types of cassava starch cast-films were produced: no-reinforcement control, two LCNF-reinforced, and two Nclay-reinforced, each at 0.65 and 1.3% w w-1. The LCNF morphology showed the characteristic microscopic structure of lignocellulose nanofibers, with an aspect ratio > 85 and average diameter of 4.5 nm. All reinforced films were transparent and had a good distribution of the nanoparticles within. The opacity values reduced for the films with all nanoreinforcements, compared to control. The permeability to water vapor reduced with reinforcements, with lower values for the films tested with LCNF 0.65 and Nclay 1.3. Thermal stability improved with 1.3% of LCNF and both concentrations of Nclay. Tensile stress for films increased and elongation at break value decreased with both types of nanoreinforcements.

Production of n-butanol from cassava bagasse hydrolysate by engineered Clostridium tyrobutyricum overexpressing adhE2: Kinetics and cost analysis.

The production of biofuels such as butanol is usually limited by the availability of inexpensive raw materials and high substrate cost. Using food crops as feedstock in the biorefinery industry has been criticized for its competition with food supply, causing food shortage and increased food prices. In this study, cassava bagasse as an abundant, renewable, and inexpensive byproduct from the cassava starch industry was used for n-butanol production. Cassava bagasse hydrolysate containing mainly glucose was obtained after treatments with dilute acid and enzymes (glucoamylases and cellulases) and then supplemented with corn steep liquor for use as substrate in repeated-batch fermentation with engineered Clostridium tyrobutyricum CtΔack-adhE2 in a fibrous-bed bioreactor. Stable butanol production with high titer (>15.0 g/L), yield (>0.30 g/g), and productivity (~0.3 g/L∙h) was achieved, demonstrating the feasibility of an economically competitive process for n-butanol production from cassava bagasse for industrial application.

Adding value to lignocellulosic wastes via their use for endoxylanase production by Aspergillus fungi.

Agroforestry industries in the world generate lignocellulosic wastes that can be a huge problem of pollution, or the wastes can be used for different biotechonological applications such as substrates for microorganism growth and enzyme production. Fungi such as Aspergillus niger can grow in almost every substrate and produce hydrolytic enzymes such as endoxylanases, giving added value to agroforestry wastes generated by industries in the northeast of Argentina. In this context, the aim of this work was to use agroforestry wastes as substrates for the production of endoxylanases by Aspergillus niger and to optimize nitrogen sources and physical variables for the highest endoxylanase activity. A. niger LBM 055 and A. niger LBM 134 produced high endoxylanase levels when they were grown with sugarcane and cassava bagasses as carbon sources. A. niger LBM 134 reached the highest endoxylanase activity when nitrogen sources and physical variables were optimized. The fungus exhibited up to 110 U mL-1 of endoxylanase activity when it was grown with sugarcane bagasse and more than 160 U mL-1 with cassava bagasse. Therefore, endoxylanase production was optimized using agricultural bagasses and cost 20 times less than enzyme production using synthetic xylan.

Process design and optimization of bioethanol production from cassava bagasse using statistical design and genetic algorithm.

Bioethanol production from agro-industrial residues is gaining attention because of the limited production of starch grains and sugarcane, and food-fuel conflict. The aim of the present study is to maximize the bioethanol production using cassava bagasse as a feedstock. Enzymatic liquefaction, by α-amylase, followed by simultaneous saccharification and fermentation (SSF), using glucoamylase and Zymomonas mobilis MTCC 2427, was investigated for bioethanol production from cassava bagasse. The factors influencing ethanol production process were identified and screened for significant factors using Plackett-Burman design. The significant factors (cassava bagasse concentration (10-50 g/L), concentration of α-amylase (5-25% (v/v), and temperature of fermentation (27-37 °C)) were optimized by employing Box-Behnken design and genetic algorithm. The maximum ethanol concentrations of 25.594 g/L and 25.910 g/L were obtained from Box-Behnken design and genetic algorithm, respectively, under optimum conditions. Thus, the study provides valuable insights in utilizing the cost-effective industrial residue, cassava bagasse, for the bioethanol production.

Enhanced single cell oil production by mixed culture of Chlorella pyrenoidosa and Rhodotorula glutinis using cassava bagasse hydrolysate as carbon source.

The single cell oil (SCO) production by the mono and mixed culture of microalgae Chlorella pyrenoidosa and red yeast Rhodotorula glutinis was investigated using non-detoxified cassava bagasse hydrolysate (CBH) as carbon source. The results suggested that the two strains were able to tolerate and even degrade some byproducts presented in the CBH, and the mixed culture approach enhanced the degradation of certain byproducts. Biomass (20.37 ±â€¯0.38 g/L) and lipid yield (10.42 ±â€¯1.21 g/L) of the mixed culture achieved in the batch culture were significantly higher than that of the mono-cultures (p < 0.05). The fed-batch culture further raised the biomass and lipid yield to 31.45 ±â€¯4.93 g/L and 18.47 ±â€¯3.25 g/L, respectively. The lipids mainly composed of oleic acid and palmitic acid, suggesting the potential applications such as biofuel feedstock, cosmetics, food additives and lubricant. This study provided new insights for the integration of the economical SCO production with agro-industrial waste disposal.

Cassava/sugar palm fiber reinforced cassava starch hybrid composites: Physical, thermal and structural properties.

A hybrid composite was prepared from cassava bagasse (CB) and sugar palm fiber (SPF) using casting technique with cassava starch (CS) as matrix and fructose as a plasticizer. Different loadings of SPF (2, 4, 6 and 8% w/w of dry starch) were added to the CS/CB composite film containing 6% CB. The addition of SPF significantly influenced the physical properties. It increased the thickness while decreasing the density, water content, water solubility and water absorption. However, no significant effect was noticed on the thermal properties of the hybrid composite film. The incorporation of SPF increased the relative crystallinity up to 47%, compared to 32% of the CS film. SEM micrographs indicated that the filler was incorporated in the matrix. The film with a higher concentration of SPF (CS-CB/SPF8) showed a more heterogeneous surface. It could be concluded that the incorporation of SPF led to changes in cassava starch film properties, potentially affecting the film performances.

Isolation and characterization of cellulose nanofibers from cassava root bagasse and peelings.

This work aimed to obtain and characterize nanofibers from cassava bagasse and peelings, which are waste originating from cassava starch extraction. To isolate the nanofibers, a combination of pre-treatments (alkaline treatment, Q-chelating treatment, bleaching), acid hydrolysis, and a final ultrasonic disintegration step were used. Acidic hydrolysis was conducted at a constant temperature of 60°C; the acid concentration (30, 40, and 50%) and the treatment time (30, 60, and 90min) were varied. The nanofibers were characterized for their morphology, surface charge, crystallinity index (XRD), and functional groups (FTIR). The diameters of the nanofibers ranged from 2.3nm to 5.4nm. The zeta potential values were lower than -47.7mV. As expected, all the products derived from acid hydrolysis displayed high crystallinity index. Finally, FTIR analysis confirmed that the isolation processes effectively removed amorphous materials such as lignin and hemicellulose from the nanofibers.

Enhanced isopropanol and n-butanol production by supplying exogenous acetic acid via co-culturing two clostridium strains from cassava bagasse hydrolysate.

The focus of this study was to produce isopropanol and butanol (IB) from dilute sulfuric acid treated cassava bagasse hydrolysate (SACBH), and improve IB production by co-culturing Clostridium beijerinckii (C. beijerinckii) with Clostridium tyrobutyricum (C. tyrobutyricum) in an immobilized-cell fermentation system. Concentrated SACBH could be converted to solvents efficiently by immobilized pure culture of C. beijerinckii. Considerable solvent concentrations of 6.19 g/L isopropanol and 12.32 g/L butanol were obtained from batch fermentation, and the total solvent yield and volumetric productivity were 0.42 g/g and 0.30 g/L/h, respectively. Furthermore, the concentrations of isopropanol and butanol increased to 7.63 and 13.26 g/L, respectively, under the immobilized co-culture conditions when concentrated SACBH was used as the carbon source. The concentrations of isopropanol and butanol from the immobilized co-culture fermentation were, respectively, 42.62 and 25.45 % higher than the production resulting from pure culture fermentation. The total solvent yield and volumetric productivity increased to 0.51 g/g and 0.44 g/L/h when co-culture conditions were utilized. Our results indicated that SACBH could be used as an economically favorable carbon source or substrate for IB production using immobilized fermentation. Additionally, IB production could be significantly improved by co-culture immobilization, which provides extracellular acetic acid to C. beijerinckii from C. tyrobutyricum. This study provided a technically feasible and cost-efficient way for IB production using cassava bagasse, which may be suitable for industrial solvent production.

Statistical modeling of pullulan production and its application in pullulan acetate nanoparticles synthesis.

This work focused on the optimization of exo-polysaccharide, pullulan production by exploiting cassava bagasse, an agricultural solid waste residue by solid state fermentation and its application in the preparation of pullulan acetate nanoparticles. Statistical approach was investigated to maximize the pullulan production using C/N ratio, initial pH, NaCl and ZnSO4·5H2O. The optimum conditions for maximum yield of pullulan (39.42±0.62mg/gds) were found to be: C/N=25.94, initial pH=5.5 and NaCl=0.55g/L. Using the optimized medium variables, the production of pullulan was investigated in lab scale solid state fermentation. The pullulan produced was characterized by thermo gravimetric and XRD analysis. Also pullulan acetate nanoparticles were synthesized from chemical modification of pullulan and the average particle size of nanoparticles was examined by zeta particle sizer.

High yields of fatty acid and neutral lipid production from cassava bagasse hydrolysate (CBH) by heterotrophic Chlorella protothecoides.

The fermentation process for high yields of fatty acid and neutral lipid production from cassava bagasse hydrolysate (CBH) was developed by heterotrophic Chlorella protothecoides. An efficient single-step enzymatic hydrolysis of cassava bagasse (CB) by cellulase was firstly developed to produce >30 g/L of reducing sugars. The concentrated CBH was subsequently applied in a batch culture, producing 7.9 g/L of dry biomass with yield of 0.44 g/g reducing sugar and 34.3 wt% of fatty acids and 48.6 wt% of neutral lipids. Furthermore, fed-batch fermentation using CBH achieved higher yields of fatty acids (41.0 wt% and a titer of 5.83 g/L) and neutral lipids (58.4 wt% and yield of 0.22 g/g reducing sugar). Additionally, the fatty acid profile analysis showed that the intercellular lipid was suitable to prepare high-quality biodiesel. This study demonstrated the feasibility of using CBH as low-cost feedstock to produce crude algal oil for sustainable biodiesel production.

Economically enhanced succinic acid fermentation from cassava bagasse hydrolysate using Corynebacterium glutamicum immobilized in porous polyurethane filler.

An immobilized fermentation system, using cassava bagasse hydrolysate (CBH) and mixed alkalis, was developed to achieve economical succinic acid production by Corynebacterium glutamicum. The C. glutamicum strains were immobilized in porous polyurethane filler (PPF). CBH was used efficiently as a carbon source instead of more expensive glucose. Moreover, as a novel method for regulating pH, the easily decomposing NaHCO3 was replaced by mixed alkalis (NaOH and Mg(OH)2) for succinic acid production by C. glutamicum. Using CBH and mixed alkalis in the immobilized batch fermentation system, succinic acid productivity of 0.42gL(-1)h(-1) was obtained from 35gL(-1) glucose of CBH, which is similar to that obtained with conventional free-cell fermentation with glucose and NaHCO3. In repeated batch fermentation, an average of 22.5gL(-1) succinic acid could be obtained from each batch, which demonstrated the enhanced stability of the immobilized C. glutamicum cells.

Bioconversion of industrial solid waste--cassava bagasse for pullulan production in solid state fermentation.

The purpose of the work was to produce commercially important pullulan using industrial solid waste namely cassava bagasse in solid state fermentation and minimize the solid waste disposal problem. First, influence of initial pH on cell morphology and pullulan yield was studied. Effect of various factors like fermentation time, moisture ratio, nitrogen sources and particle size on pullulan yield was investigated. Various supplementary carbon sources (3%, w/w) namely glucose, sucrose, fructose, maltose, mannose and xylose with cassava bagasse was also studied to improve the pullulan yield. After screening the suitable supplement, effect of supplement concentration on pullulan production was investigated. The pullulan from cassava bagasse was characterized by FTIR, (1)H-NMR and (13)C-NMR. Molecular weight of pullulan from cassava bagasse was determined by gel permeation chromatography. Thus, cassava bagasse emerged to be a cheap and novel substrate for pullulan production.