Optimization of oxalate-free starch production from Taro flour by oxalate oxidase assisted process.

Taro (Colocasia esculenta) starch is known to possess unique physical and functional properties such as low amylose content, A-crystalline form, small granules, higher swelling power, etc. Due to the presence of significant amount of calcium oxalate crystals, the food industry is reluctant to explore this unique and cheap starch source for various food applications. Traditional processes utilizing various physical and chemical methods to remove oxalate content of starch inevitably change its physical and functional properties. However, using oxalate oxidase can effectively remove oxalates without altering the unique properties of starch. Hence, an attempt was made to optimize oxalate oxidase assisted starch extraction process from taro flour using response surface methodology. A central composite design comprising 20 experimental trials with 10 cube points augmented with six axial points and four replicates at the center point was applied. A mathematical model was developed to show the effect of taro flour concentration, enzyme load and incubation time on the oxalate removal. Validity of the model was experimentally verified and found that 98.3% of total oxalates can be removed under optimal conditions. This is the first report of optimization of the production of starch from taro flour using microbial oxalate oxidase.

Physical properties and in-vitro gastrointestinal digestion of oil-in-water emulsions stabilized by single- and dual-modified cassava starches with cross-linking and octenylsuccinylation.

The different modified cassava starches (MCS) obtained by either single or dual modifications with cross-linking (CL) and octenylsuccinylation (OS), including 2%CL, 3%OS, 2%CL-3%OS, and 3%OS-2%CL, were used to stabilize soybean oil-in-water emulsions (oil content 10% (w/w)) at a concentration of 4.5% (w/w) compared to native cassava starch (NCS) and their physical properties and in-vitro gastrointestinal digestion were investigated. The emulsions stabilized with NCS and 2%CL-MCS had larger oil droplet sizes, higher viscosity, and lower negative charge than the emulsions stabilized by single- or dual-MCS with 3%OS. All MCS-stabilized emulsions showed a higher emulsion stability against creaming than the NCS-stabilized emulsion. Under a simulated gastrointestinal tract, all 3%OS-MCS promoted droplet flocculation, while the less ionic NCS and the 2%CL-MCS showed a decrease in droplet size after passing through the mouth and stomach stages. The lipid digestion rate of emulsions stabilized with different MCS and NCS followed the following order: 3%OS >2%CL-3%OS > 3%OS-2%CL > 2%CL > NCS. The NCS- and 2%CL-stabilized emulsions had a lower lipid digestion rate, possibly due to the larger droplet sizes and higher viscosity of the initial emulsions, which delays access of lipase enzymes to lipid droplet surfaces, compared to all 3%OS-MCS-stabilized emulsions.

Impact of Oil Addition on Physicochemical Properties and In Vitro Digestibility of Extruded Pineapple Stem Starch.

The effects of palm oil (PO) and coconut oil (CO) additions on the physicochemical properties and in vitro starch digestibility of extruded pineapple stem starch (PSS) were studied. The native PSS was adjusted to 15% moisture and blended with PO or CO in amounts of 5 and 10% (w/w of starch), while the control sample without added oil was adjusted to 25% moisture before being extruded with a twin-screw extruder at a maximum barrel temperature of 140 °C. Due to the lubricating effect, the added oils reduced the expansion ratio of the extrudates, which led to an increase in cell wall thickness, bulk density, hardness, and water adsorption index, but to a reduction in the water solubility index, especially with 10% oils. PO had a greater impact on the physicochemical changes in the extrudates than CO. Surprisingly, no amylose-lipid complex was observed in the extrudates with added oil, as shown by XRD, DSC, and FTIR results. The phenolic compounds contained in PSS remained in all extrudates, which could affect the formation of the amylose-lipid complex during extrusion. The addition of 5% oil had no effect on the digestibility of the starch compared to the control extrudates, while the 10% oils, both PO and CO, reduced the rapidly digestible starch content but significantly increased the resistant starch content of the extruded PSS.

Effect of single and dual modifications with cross-linking and octenylsuccinylation on physicochemical, in-vitro digestibility, and emulsifying properties of cassava starch.

Native cassava starch (NCS) was chemically modified by cross-linking (CL), octenylsuccinylation (OS), CL followed by OS, and OS followed by CL. The modified cassava starches (MCS) were determined for physicochemical, in-vitro digestibility, and emulsifying properties. For the dual modifications, the functional groups introduced in the first modification were partially replaced by the ones that introduced in the second modification. The X-ray diffraction pattern and relative crystallinity of cassava starch did not change by both modifications, indicating that both reactions occurred predominantly in amorphous regions as well as on the surface of starch granules and did not alter the crystalline pattern in the granules. The physicochemical and emulsifying properties of the dual MCS were predominantly affected by the functional groups introduced in the second modification. For the in-vitro digestibility, the dual MCS exhibited the highest resistant starch content of 19.48-22.00% in comparison with the NCS (6.05%) and the single MCS (10.76-14.49%), possibly due to a synergistic effect of the functional groups introduced in the first and second modifications.

Effect of Pulsed Electric Field Treatment on the Protein, Digestibility, and Physicochemical Properties of Starch Granules in Wheat Flour.

The effect of pulsed electric field (PEF) treatment depends mainly on the electric field strength and treatment time. In this study, wheat flour-water suspensions were treated with PEF at an electric field strength of 3 kV/cm for 0 to 1400 pulses to obtain a specific energy input of 0 to 656 kJ/kg. The effect of PEF on the removal or unfolding of proteins from the starch surface, digestibility, starch granule structure, and physicochemical properties of wheat flour was studied. The removal of proteins from the surface and the damage to the internal structure of wheat starch granules after PEF treatment was detected by confocal laser scanning microscopy (CLSM) and FTIR. The damage of the PEF-treated wheat starch granules was observed by scanning electron microscopy (SEM). From CLSM results, penetration of dextran (Mw 10,000 Da) into starch granules of wheat flour was dependent on the energy input of PEF. The high the energy input showed the intense penetration of the biopolymer. The benefits of the accessibility of biopolymer in starch granules are to increase enzyme digestion, especially rapidly digestible starch (RDS). The RDS of wheat flour treated with PEF at 656 kJ/kg was 41.72%, whereas the RDS of wheat flour control was 27.59%.

Effect of heat-moisture treatment on the physicochemical properties and digestibility of proso millet flour and starch.

Proso millet flour (PMF) and starch (PMS) were subjected to heat-moisture treatment (HMT) at 25 % moisture content and 110 °C for 4 h. The effects of HMT on physicochemical and structural properties and in vitro digestibility of PMF and PMS were analyzed. After HMT, SEM showed aggregation and damage to the surface of starch granules, while CLSM showed proteins wrapped around the granules. The amylopectin chain length distribution (CLD) remained unchanged in PMF and PMS after HMT, indicating intact covalent bonds between glucose units. HMT decreased the swelling power, solubility, viscosity of the paste, and gelatinization enthalpy and increased the pasting temperature and gelatinization temperature of PMF and PMS. HMT changed the XRD pattern of PMF from A to A + V type starches, whereas that of PMS remained unchanged. FTIR study showed an increase in the degree of short-range molecular order of PMF and PMS after HMT. In vitro digestibility evaluation showed that the rapidly (RDS) and slowly digestible starch (SDS) contents of PMF and PMS increased, whereas the resistant starch (RS) content decreased after HMT. HMT flour and starch have suitable properties for use in a wide range of food products, from canned to frozen, as well as non-food products.

Toward a Circular Bioeconomy: Exploring Pineapple Stem Starch Film as a Plastic Substitute in Single Use Applications.

In this study, biodegradable starch film was developed from pineapple stem waste as a substitute for non-biodegradable petroleum-based films for single-use applications where strength is not too demanding. High amylose starch from a pineapple stem was used as the matrix. Glycerol and citric acid were used as additives to adjust the ductility of the material. Glycerol content was fixed at 25% while that of citric acid varied from 0 to 15% by weight of starch. Films with a wide range of mechanical properties can be prepared. As more citric acid is added, the film becomes softer and weaker, and has greater elongation at the break. Properties range from a strength of about 21.5 MPa and 2.9% elongation to a strength of about 6.8 MPa and 35.7% elongation. An X-ray diffraction study showed that the films were semi-crystalline. The films were also found to be water-resistant and can be heat-sealed. An example of a single-use package was demonstrated. A soil burial test confirmed that the material was biodegradable and completely disintegrated into sizes smaller than 1 mm within one month.

Physicochemical, Rheological, In-Vitro Digestibility, and Emulsifying Properties of Starch Extracted from Pineapple Stem Agricultural Waste.

In this study, the physicochemical, rheological, in vitro starch digestibility, and emulsifying properties of starch extracted from pineapple stem agricultural waste were investigated in comparison with commercial cassava, corn, and rice starches. Pineapple stem starch had the highest amylose content (30.82%), which contributed to the highest pasting temperature (90.22 °C) and the lowest paste viscosity. It had the highest gelatinization temperatures, gelatinization enthalpy, and retrogradation. Pineapple stem starch gel had the lowest freeze-thaw stability, as evidenced by the highest syneresis value of 53.39% after five freeze-thaw cycles. Steady flow tests showed that pineapple stem starch gel (6%, w/w) exhibited the lowest consistency coefficient (K) and the highest flow behavior index (n), while dynamic viscoelastic measurements gave the gel strength in the following order: rice > corn > pineapple stem > cassava starch gel. Interestingly, pineapple stem starch provided the highest slowly digestible starch (SDS) (48.84%) and resistant starch (RS) (15.77%) contents compared to other starches. The oil-in-water (O/W) emulsion stabilized with gelatinized pineapple stem starch exhibited higher emulsion stability than that stabilized with gelatinized cassava starch. Pineapple stem starch could therefore be used as a promising source of nutritional SDS and RS, and as an emulsion stabilizer for food applications.

Toward a Circular Bioeconomy: Development of Pineapple Stem Starch Composite as a Plastic-Sheet Substitute for Single-Use Applications.

Plastic waste poses a significant challenge for the environment, particularly smaller plastic products that are often difficult to recycle or collect. In this study, we developed a fully biodegradable composite material from pineapple field waste that is suitable for small-sized plastic products that are difficult to recycle, such as bread clips. We utilized starch from waste pineapple stems, which is high in amylose content, as the matrix, and added glycerol and calcium carbonate as the plasticizer and filler, respectively, to improve the material's moldability and hardness. We varied the amounts of glycerol (20-50% by weight) and calcium carbonate (0-30 wt.%) to produce composite samples with a wide range of mechanical properties. The tensile moduli were in the range of 45-1100 MPa, with tensile strengths of 2-17 MPa and an elongation at break of 10-50%. The resulting materials exhibited good water resistance and had lower water absorption (~30-60%) than other types of starch-based materials. Soil burial tests showed that the material completely disintegrated into particles smaller than 1 mm within 14 days. We also created a bread clip prototype to test the material's ability to hold a filled bag tightly. The obtained results demonstrate the potential of using pineapple stem starch as a sustainable alternative to petroleum-based and biobased synthetic materials in small-sized plastic products while promoting a circular bioeconomy.

Toward a Circular Bioeconomy: Exploring Pineapple Stem Starch Film as Protective Coating for Fruits and Vegetables.

In order to reduce our dependence on nonrenewable plastics and solve the problem of non-biodegradable plastic waste, there has been much attention paid to the development of biodegradable plastics from natural resources. Starch-based materials have been widely studied and developed for commercial production, primarily from corn and tapioca. However, the use of these starches could generate food security problems. Therefore, the use of alternative starch sources, such as agricultural waste, would be of great interest. In this work, we investigated the properties of films prepared from pineapple stem starch, which has a high amylose content. Pineapple stem starch (PSS) films and glycerol-plasticized PSS films were prepared and characterized using X-ray diffraction and water contact angle measurements. All films exhibited some degree of crystallinity, making them water-resistant. The effect of glycerol content on mechanical properties and gas (oxygen, carbon dioxide and water vapor) transmission rates was also studied. The tensile modulus and tensile strength of the films decreased with increasing glycerol content, while gas transmission rates increased. Preliminary studies showed that coatings made from PSS films could slow down the ripening process of bananas and extend their shelf life.

Development of Biodegradable Rigid Foams from Pineapple Field Waste.

Pineapple materials sourced from agricultural waste have been employed to process novel bio-degradable rigid composite foams. The matrix for the foam consisted of starch extracted from pineapple stem, known for its high amylose content, while the filler comprised non-fibrous cellulosic materials sourced from pineapple leaf. In contrast to traditional methods that involve preparing a batter, this study adopted a unique approach where the starch gel containing glycerol were first formed using a household microwave oven, followed by blending the filler into the gel using a two-roll mill. The resulting mixture was then foamed at 160 °C using a compression molding machine. The foams displayed densities ranging from 0.43-0.51 g/cm3 and exhibited a highly amorphous structure. Notably, the foams demonstrated an equilibrium moisture content of approximately 8-10% and the ability to absorb 150-200% of their own weight without disintegration. Flexural strengths ranged from 1.5-4.5 MPa, varying with the filler and glycerol contents. Biodegradability tests using a soil burial method revealed complete disintegration of the foam into particles measuring 1 mm or smaller within 15 days. Moreover, to showcase practical applications, an environmentally friendly single-use foam tray was fabricated. This novel method, involving gel formation followed by filler blending, sets it apart from previous works. The findings highlight the potential of pineapple waste materials for producing sustainable bio-degradable foams with desirable properties and contribute to the field of sustainable materials.

Effect of spent brewer's yeast ß-D-glucan on properties of wheat flour dough and bread during chilled storage.

Effect of spent brewer's yeast ß-D-glucan incorporation (0.25-2.00%, w/w wheat flour) on the characteristics of wheat flour dough and bread during chilled storage at 4 °C for 8 days was investigated. The dough containing 0.75% yeast ß-D-glucan had the highest strength, work of adhesion, and stickiness. The addition of yeast ß-D-glucan up to 0.75% yielded the breads with an appearance comparable to the control bread (without yeast ß-D-glucan). The staling of bread was retarded by the addition of yeast ß-D-glucan up to 0.75% as evidenced by the higher retained moisture content and cohesiveness and the lower L* value and hardness of the bread crumb during chilled storage compared to the control and the 1.00-2.00% yeast ß-D-glucan breads. The 0.75% yeast ß-D-glucan bread exhibited the lowest melting enthalpy of retrograded starch (ΔHret), the lowest B-type- and total crystallinities, the least microstructure change of the crumb matrix, and the highest consumer acceptance after 4 days chilled storage. These results suggested that the incorporation of an appropriate amount of yeast ß-D-glucan could improve the quality and shelf life of bread or other starch-based food products during chilled storage.

Physicochemical and rheological properties of flour and starch from Thai pigmented rice cultivars.

Flour and starch from four Thai pigmented rice cultivars, i.e., Riceberry (RB), Hom Nil (HN), Niaw Dang (ND), and Kum Pleuak Khao (KP) were compared for their physicochemical and rheological properties. Amylose content of all rice starches decreased in the following order: RB (12.09%) > HN (8.14%) > KP (2.87%) ~ ND (2.77%). The HN starch had the lowest proportion of amylopectin short A chains, while the KP starch showed the highest. Pasting temperature, setback, and final viscosity increased, while breakdown and swelling power decreased with increasing amylose content for both flour and starch samples. The flours and starches from the RB and HN showed greater onset and peak temperatures and enthalpy change (ΔH) of gelatinization than those from the ND and KP. Moreover, the gelatinization temperatures of all starches were significantly lower, but ΔH was higher than their flour counterparts. Dynamic viscoelastic tests revealed weak-gel like behavior of all flour and starch gels as evidenced by their G' > G″ and tan δ values were smaller than unity.

Effect of cross-linking on physicochemical properties of tapioca starch and its application in soup product.

Physicochemical properties of cross-linked tapioca starch (CLTS) with different cross-linking levels and their application as a thickening agent in soups were studied. The CLTS was prepared by cross-linking native tapioca starch suspended in alkaline solution (41.67% (w/w), pH 11) using a mixture (99:1 (w/w) ratio) of sodium trimetaphosphate (STMP) and sodium tripolyphosphate (STPP) at different concentrations ranged from 0.25% to 6.0% (w/w of starch) at 45°C for 3h. Starch paste clarity decreased with increasing concentration of STMP/STPP mixture. Variations of swelling power, solubility, pasting, gelatinization, and rheological properties of the CLTS were found. Thermogravimetric analysis exhibited higher thermal stability for the CLTS granules compared to the native one. Among the samples, the CLTS prepared using 1.0% STMP/STPP (1.0%-CLTS) and soup containing the 1.0%-CLTS exhibited the strongest gel characteristic and the greatest shear resistant properties. The 1.0%-CLTS improved the textural properties and sensory quality of soups.

Modification of tapioca starch by non-chemical route using jet atmospheric argon plasma.

Non-chemical modification of tapioca starch was investigated using jet atmospheric argon plasma treatment. Two forms of starch slurry, i.e. granular starch (G) and cooked starch (C), were jet-treated by argon plasma generated by supplying input power of 50 W (denoted as G50 and C50 samples) and 100 W (denoted as G100 and C100 samples) for 5 min. Physical, rheological, and structural characteristics of the modified starch were investigated. The G50 and C100 samples had lower paste clarity but higher thermal stability and performed stronger gels (G50 only) compared to their control counterparts. On the other hand, the analyzed properties of the G100 and C50 samples showed the opposite trend. FTIR and (1)H NMR results revealed that the relative areas of COC and OH peaks were changed after the treatment. Cross-linking reaction seemed to predominantly take place for the G50 and C100 samples, whereas depolymerization predominated for the G100 and C50 samples.