Importance of Inactivation Methodology in Enzymatic Processing of Raw Potato Starch: NaOCl as Efficient α-Amylase Inactivation Agent.

Efficient inactivation of microbial α-amylases (EC 3.2.1.1) can be a challenge in starch systems as the presence of starch has been shown to enhance the stability of the enzymes. In this study, commonly used inactivation methods, including multistep washing and pH adjustment, were assessed for their efficiency in inactivating different α-amylases in presence of raw potato starch. Furthermore, an effective approach for irreversible α-amylase inactivation using sodium hypochlorite (NaOCl) is demonstrated. Regarding inactivation by extreme pH, the activity of five different α-amylases was either eliminated or significantly reduced at pH 1.5 and 12. However, treatment at extreme pH for 5 min, followed by incubation at pH 6.5, resulted in hydrolysis yields of 42-816% relative to controls that had not been subjected to extreme pH. "Inactivation" by multistep washing with water, ethanol, and acetone followed by gelatinization as preparation for analysis gave significant starch hydrolysis compared to samples inactivated with NaOCl before the wash. This indicates that the further starch degradation observed in samples subjected to washing only took place during the subsequent gelatinization. The current study demonstrates the importance of inactivation methodology in α-amylase-mediated raw starch depolymerization and provides a method for efficient α-amylase inactivation in starch systems.

Enzymatic potato starch modification and structure-function analysis of six diverse GH77 4-alpha-glucanotransferases.

4-α-glucanotransferase (EC 2.4.1.25) mediated glucan transfer in starch provides opportunities for production of clean label starch ingredients with unique gelling properties. 4-α-glucanotransferases can be found in glycoside hydrolase (GH) family GH13, GH57, and in the monospecific glycoside hydrolase family 77 (GH77). Here, pH-temperature optima, steady-state kinetics, potato starch modifying properties and structural folds are reported for six phylogenetically distinct GH77 members, representing four different domain architectures including a novel multi-domain 4-α-glucanotransferase from Lactococcus lactis. Four of the enzymes exhibited starch modifying activity leading to a gradual decrease of the amylose content, elongation of amylopectin chains, and enabled formation of firm starch gels. Unexpectedly, these diverse enzymes catalyzed similar changes in chain length distributions. However, the amylose depletion and amylopectin elongation rates spanned more than two orders of magnitude between the enzyme showing very different specific activities. Tt4αGT from Thermus thermophilus had highest temperature optimum (73 °C) and superior potato starch modifying efficacy compared to the other five enzymes.

Application of multistage induced electric field for acid hydrolysis of starch in a continuous-flow reactor.

Herein, a multistage induced electric field (IEF) combined with a continuous-flow reactor was utilized to assist the acid hydrolysis of corn, potato, and waxy corn starch for avoiding plate corrosion and heavy metal leakage. It was found that adding IEF stages was beneficial to improve the hydrolysis efficiency. Treating potato, corn, and waxy corn starch via continuous-flow IEF increased the reducing sugar contents up to 78.76 %, 57.86 %, and 66.18 %, respectively. The electrical conductivity of starch grew with the reaction stages, while starch yield demonstrated the opposite trend. Treated starch had higher solubility and gelatinization peak temperature than native starch, with the gelatinization enthalpy showing fluctuations. Meanwhile, the swelling power decreased as the number of IEF stages was increased. Observations of Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy indicated that the treated starch became more ordered, and crystalline regions were destroyed to various degrees with pores forming on particle surfaces. These variations could be attributed to acid hydrolysis and IEF.

Starch-based materials encapsulating food ingredients: Recent advances in fabrication methods and applications.

Encapsulation systems have gained significant interest in designing innovative foods, as they allow for the protection and delivery of food ingredients that have health benefits but are unstable during processing, storage and in the upper gastrointestinal tract. Starch is widely available, cheap, biodegradable, edible, and easy to be modified, thus highly suitable for the development of encapsulants. Much efforts have been made to fabricate various types of porous starch and starch particles using different techniques (e.g. enzymatic hydrolysis, aggregation, emulsification, electrohydrodynamic process, supercritical fluid process, and post-processing drying). Such starch-based systems can load, protect, and deliver various food ingredients (e.g. fatty acids, phenolic compounds, carotenoids, flavors, essential oils, irons, vitamins, probiotics, bacteriocins, co-enzymes, and caffeine), exhibiting great potentials in developing foods with tailored flavor, nutrition, sensory properties, and shelf-life. This review surveys recent advances in different aspects of starch-based encapsulation systems including their forms, manufacturing techniques, and applications in foods.

Ultrasound assisted acid hydrolyzed structure modification and loading of antioxidants on potato starch nanoparticles.

Starch is second most abundant biomaterial available after cellulose but the intensity of research on starch is less compared to cellulose. It is a carbohydrate based polymer synthesized in plants for the storage of the energy. Major percentage of starch is being utilized by food industries as raw material for giving texture, flavor, gelling, fat replacement etc. and also has multiple applications in different area due to its biological origin and properties. Native starch possesses low shear stress, poor thermal properties and less digestion resistance and retro-gradation. Thus, it has to be modified using physical, chemical, enzymatic and/or genetic treatments. Physical and chemical modifications using ultrasound and acid hydrolysis is time-efficient and effective process. These economical treatments are predominant for production of digestion resistant starch with increased shelf-life and thermal properties. Ultrasound assisted acid hydrolyzed starch (potato) exfoliates the native starch and modifies the structural arrangement. On acid treatment the amorphous nature of starch converted to crystalline nature. The physical and structural properties of the native starch were enhanced. The digestibility and structure of the modified starch effects on the double helices structure of starch. The size of the starch particle was changed from 1596 nm (Conventional) to 80 and 42 nm on ultrasonication and acid hydrolyzed ultrasonication approaches respectively. The crystallite of the particles was evaluated from XRD analysis. From TEM analysis the starch nanoparticles were found to have spherical morphology.

Synthesis and evaluation of acryloylated starch-g-poly (Acrylamide/Vinylmethacrylate/1-Vinyl-2-pyrrolidone) crosslinked terpolymer functionalized by dimethylphenylvinylsilane derivative as a novel polymer-flooding agent.

Starch is a natural biopolymer that subjected to various chemical modifications through different industrial applications. Molecular structure of starch allow its grafting with different vinyl monomers in the presence of crosslinking agents to synthesize cross-linked hydrogels, which used in enhanced oil recovery (EOR) applications, water shutoff and drag reduction. Application of native starch in the field of petroleum reservoirs as a flooding agent suffer from some limitations concerned with microbial degradation, thermal and salinity resistance under harsh petroleum reservoir conditions. In the current research, we stated the synthesis of acryloylated starch then it's grafting with poly (Acrylamide/Vinylmethacrylate/1-Vinyl-2-pyrrolidone) terpolymer in presence of dimethylphenylvinylsilane through emulsification polymerization. Characterization and structure determination occur by different spectroscopic techniques as stated throughout the manuscript. Rheological and solution properties carried out as a function of shear rate, salinity and temperature at simulated reservoir conditions. Flooding tests carried out through linear-dimensional sandstone model at simulated reservoir conditions, and recovered oil amount calculated on volumetric basis. The obtained results indicate that the prepared starch-g-terpolymer can tolerate to severe flooding conditions of high temperature and salinity, moreover it can increase recovery factor up to 49% of residual oil saturation so considered as a promised EOR candidate.

Encapsulation and delivery of food ingredients using starch based systems.

Functional ingredients can be encapsulated by various wall materials for controlled release in food and digestion systems. Starch, as one of the most abundant natural carbohydrate polymers, is non-allergenic, GRAS, and cheap. There has been increasing interest of using starch in native and modified forms to encapsulate food ingredients such as flavours, lipids, polyphenols, carotenoids, vitamins, enzymes, and probiotics. Starches from various botanical sources in granular or amorphous forms are modified by chemical, physical, and/or enzymatic means to obtain the desired properties for targeted encapsulation. Other wall materials are also employed in combination with starch to facilitate some types of encapsulation. Various methods of crafting the starch-based encapsulation such as electrospinning, spray drying, antisolvent, amylose inclusion complexation, and nano-emulsification are introduced in this mini-review. The physicochemical and structural properties of the particles are described. The encapsulation systems can positively influence the controlled release of food ingredients in food and nutritional applications.

Structural and physical properties of granule stabilized starch obtained by branching enzyme treatment.

Chemical cross-linking of starch is an important modification used in the industry for granule stabilization. It has been demonstrated that treatment with branching enzyme (BE) can stabilize the granular structure of starch and such treatment thereby provides a potential clean alternative for chemical modification. This study demonstrates that such BE-assisted stabilization of starch granules led to partial protection from BE catalysis of both amylose (AM) and amylopectin (AP) in their native state as assessed by triiodide complexation, X-ray diffractometry (XRD) and differential scanning calorimetry (DSC). The granule stabilizing effects were inversely linked to hydration of the starch granules, which was increased by the presence of starch-phosphate esters and suppressed by extreme substrate concentration. The data support that the granule stabilization is due to the intermolecular transglycosylation occurring in the initial stages of the reaction prior to AM-AP phase separation. The enzyme activity needed to obtain granule stabilization was therefore dependent on the hydration capability of the starch used.