Properties and applications of starch modifying enzymes for use in the baking industry

Effect of Fold-Promoting Mutation and Signal Peptide Screening on Recombinant Glucan 1,4-Alpha-maltohydrolase Secretion in Pichia pastoris

Glucan 1,4-alpha-maltohydrolase (3.2.1.133, GMH) is an important biocatalyst in the baking industry, which could delay the retrogradation of bread and improve its cold-storage durability. In the present study, a newly cloned Thgmh was characterized and secreted by Pichia pastoris (Komagataella pastoris). After computationally assisted rational design that promotes peptide folding, the maltogenic activity in supernatant was enhanced 1.6-fold in comparison with the base strain. The signal leading sequence screening and the gene dosage increment further improved secretion by approximately 6.4-fold. The purified rationally designed ThGMHs exhibited maximal activity against soluble starch at pH 7.0 and 60 ℃, and maltose is the main catalytic product. In a 5-L bioreactor, conventional fed-batch fermentation resulted in 6130 U mL-1 extracellular maltogenic activity. Therefore, a promising strain for GMH production was developed, which provides a useful reference for the secretory production of other industrial enzymes.

Catalytic activity enhancement of 1,4-α-glucan branching enzyme by N-terminal modification

The 1,4-α-glucan branching enzyme (GBE, EC 2.4.1.18) has garnered considerable attention for its ability to increase the degree of branching of starch and retard starch digestion, which has great industrial applications. Previous studies have reported that the N-terminal domain plays an important role in the expression and stability of GBEs. To further increase the catalytic ability of Gt-GBE, we constructed five mutants in the N-terminal domain: L19R, L19K, L25R, L25K, and L25A. Specific activities of L25R and L25A were increased by 28.46% and 23.46%, respectively, versus the wild-type Gt-GBE. In addition, the α-1,6-glycosidic linkage ratios of maltodextrin samples treated with L25R and L25A increased to 5.71%, which were significantly increased by 19.96% compared with that of the wild-type Gt-GBE. The results of this study suggest that the N-terminal domain selective modification can improve enzyme catalytic activity, thus further increasing the commercial application of enzymes in food and pharmaceutical industries.

Functional and Tableting Properties of Alkali-Isolated and Phosphorylated Barnyard Millet (Echinochloa esculenta) Starch

The functional and tableting properties of barnyard millet starch (Echinochloa esculenta) were investigated in its native (alkali-treated) and chemically modified (phosphorylated) states. The grains were pulverized, soaked, and ground before filtration to separate starch and protein. Multiple NaOH treatments were performed. The starch was washed, neutralized, and dried. Sodium tripolyphosphate (STPP) and sodium sulfate were used to modify the starch, followed by maceration, washing, and drying to remove unreacted chemicals. The amylose content of alkali-treated barnyard millet starch increased by 19.96 ± 3.56% w/w. The amount of protein, the kind of starch used, and the size of the starch granules, all affected the ability of the starch granules to swell up. It was observed that alkali-extracted barnyard millet starch (AZS) has a swelling power of 194.3 ± 0.0064% w/w. The swelling capacity of treated starch was lesser as compared to the native alkali barnyard millet starch. Decrement in swelling power of phosphorylated starch was observed due to tightening of bonds in the molecular structure. The moisture content of the excipients may affect the overall stability of the formulation. The moisture content of the AZS was found to be 15.336 ± 1.012% w/w. Compared to AZS, cross-linked barnyard millet starch had a moisture content that was up to 20% lower than AZS. The Hausner ratio for phosphorylated starch was found to be 1.25, which indicates marked flow property. Similar morphologies could be seen in the alkali-isolated barnyard millet starch and the cross-linked/phosphorylated barnyard millet that was cross-linked using a mixture of sodium sulfate and sodium tripolyphosphate. The modest degree of substitution would have no effect on the surface morphology as shown by the scanning electron microscopic study. The crushing and compacting abilities of modified barnyard millet starch were also improved, but its friability and rate of disintegration were decreased. The whole study revealed that after cross-linking, barnyard millet had good tableting properties and it can be used as an excipient in drug delivery.

Pullulanase: unleashing the power of enzyme with a promising future in the food industry

Pullulanases are the most important industrial group of enzymes in family 13 glycosyl hydrolases. They hydrolyze either α-1,6 and α-1,4 or both glycosidic bonds in pullulan as well as other carbohydrates to produce glucose, maltose, and maltotriose syrups, which have important uses in food and other related sectors. However, very less reports are available on pullulanase production from native strains because of low yield issues. In line with the increasing demands for pullulanase, it has become important to search for novel pullulanase-producing microorganisms with high yields. Moreover, high production costs and low yield are major limitations in the industrial production of pullulanase enzymes. The production cost of pullulanase by using the solid-state fermentation (SSF) process can be minimized by selecting agro-industrial waste. This review summarizes the types, sources, production strategies, and potential applications of pullulanase in different food and other related industries. Researchers should focus on fungal strains producing pullulanase for better yield and low production costs by using agro-waste. It will prove a better enzyme in different food processing industries and will surely reduce the cost of products.

A combined use of different functional additives for improvement of wheat flour quality for bread making

BACKGROUND

Low-protein wheat flour can produce bread with poor texture and appearance, reducing its nutritional value and market appeal. This is a growing concern for both the food industry and consumers relying on wheat as a dietary staple. The present study evaluated the individual and combined effects of bacterial xylanase (BX), maltogenic α-amylase (MG), vital gluten (VG) and ascorbic acid (AA) with respect to improving weak flour properties for bread making.

RESULTS

BX, VG and AA improved gluten Index (GI), whereas MG was employed for optimizing amylolytic-activity in flour. VG increased the water absorption (WA) capacity of flour and prolonged dough development time (DDT). The dough stability (DST) was increased by BX and VG. BX and MG decreased crumb firmness (CF) and showed anti-staling effect. All additives reduced bake loss, increased loaf volume (LV) and retained or improved sensory attributes of bread. However, MG at 60 mg kg-1 (MG60), BX at 30 mg kg-1 (BX30), VG at 5% (VG5) and AA at 50 mg kg-1 (AA50) were found to be the most suitable for evaluating in combinations. Ternary combinations of MG60, BX30, VG5 or AA50 imparted significantly (P < 0.05) positive impacts on GI, WA, DDT, DST, CF, LV and sensory attributes compared to control, individual and binary combinations.

CONCLUSION

The PCA suggested that a combination of MG60 + VG5 was more similar to MG60 + BX30 + VG5, whereas, MG60 + BX30 and MG60 + AA50 were more related to MG60 + BX30 + AA50 combination, but all of these combinations showed the improvement in the characteristics compared to control flour. © 2023 Society of Chemical Industry.

Olive Oil-Based Oleogel as Fat Replacer in a Sponge Cake: A Comparative Study and Optimization

Oleogels (defined as structured solid-like materials with a high amount of oil entrapped within a three-dimensional network of gelator molecules) represent a healthy alternative to fats that are rich in saturated and trans fatty acids. Given its fatty acids composition (oleic, linoleic, and linolenic acids), olive oil is an excellent candidate for the use of oleogels in the food industry. In this study, a D-optimal mixture design was employed to optimize the replacement of butter with olive oil-based oleogel in a type of sponge cake formulation: the plum cake. In addition, emulsifiers and whey proteins were used as recipe ingredients to extend the product’s shelf life by delaying staling phenomena and mold growth. In the experimental design, oleogel, emulsifier, and whey protein variables were set as the ingredients that change in specific ranges, while hardness, porosity, water activity, and moistness were used to characterize the obtained formulations. The experimental data of each response were fitted through polynomial regression models with the aim of identifying the best plum cake formulation. The results revealed that the best mixture was the formulation containing 76.98% olive oil-based oleogel, 7.28% emulsifier E471, and 15.73% whey protein. We stored the optimized plum cake for 3 months at room temperature and then checked for any hardness and moistness changes or mold spoilage.

Structural Modifications and Strategies for Native Starch for Applications in Advanced Drug Delivery

Pharmaceutical excipients are compounds or substances other than API which are added to a dosage form, these excipients basically act as carriers, binders, bulk forming agents, colorants, and flavouring agents, and few excipients are even used to enhance the activity of active pharmaceutical ingredient (API) and various more properties. However, despite of these properties, there are problems with the synthetic excipients such as the possibility of causing toxicity, inflammation, autoimmune responses, lack of intrinsic bioactivity and biocompatibility, expensive procedures for synthesis, and water solubility. However, starch as an excipient can overcome all these problems in one go. It is inexpensive, there is no toxicity or immune response, and it is biocompatible in nature. It is very less used as an excipient because of its high digestibility and swelling index, high glycemic index, paste clarity, film-forming property, crystalline properties, etc. All these properties of starch can be altered by a few modification processes such as physical modification, genetic modification, and chemical modification, which can be used to reduce its digestibility and glycemic index of starch, improve its film-forming properties, and increase its paste clarity. Changes in some of the molecular bonds which improve its properties such as binding, crystalline structure, and retrogradation make starch perfect to be used as a pharmaceutical excipient. This research work provides the structural modifications of native starch which can be applicable in advanced drug delivery. The major contributions of the paper are advances in the modification of native starch molecules such as physically, chemically, enzymatically, and genetically traditional crop modification to yield a novel molecule with significant potential for use in the pharmaceutical industry for targeted drug delivery systems.

Cold plasma technologies: Their effect on starch properties and industrial scale-up for starchmodification

Native starches have limited applications in the food industry due to their unreactive and insoluble nature. Cold plasma technology, including plasma-activated water (PAW), has been explored to modify starches to enhance their functional, thermal, molecular, morphological, and physicochemical properties. Atmospheric cold plasma and low-pressure plasma systems have been used to alter starches and have proven successful. This review provides an in-depth analysis of the different cold plasma setups employed for starch modifications. The effect of cold plasma technology application on starch characteristics is summarized. We also discussed the potential of plasma-activated water as a novel alternative for starch modification. This review provides information needed for the industrial scale-up of cold plasma technologies as an eco-friendly method of starch modification.

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Cold plasma technology could be an effective, sustainable alternative for starch modification.

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The extent of modification of starches from different botanical sources depends on the type of cold plasma technology used.

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For mainstream adoption of cold plasma modified starches, research on safety and consumer perception must be conducted.

Identification of an Amylomaltase from the Halophilic Archaeon Haloquadratum walsbyi by Functional Metagenomics: Structural and Functional Insights

Amylomaltases are prokaryotic 4-α-glucanotransferases of the GH77 family. Thanks to the ability to modify starch, they constitute a group of enzymes of great interest for biotechnological applications. In this work we report the identification, by means of a functional metagenomics screening of the crystallization waters of the saltern of Margherita di Savoia (Italy), of an amylomaltase gene from the halophilic archaeon Haloquadratum walsbyi, and its expression in Escherichia coli cells. Sequence analysis indicated that the gene has specific insertions yet unknown in homologous genes in prokaryotes, and present only in amylomaltase genes identified in the genomes of other H. walsbyi strains. The gene is not part of any operon involved in the metabolism of maltooligosaccharides or glycogen, as it has been found in bacteria, making it impossible currently to assign a precise role to the encoded enzyme. Sequence analysis of the H. walsbyi amylomaltase and 3D modelling showed a common structure with homologous enzymes characterized in mesophilic and thermophilic bacteria. The recombinant H. walsbyi enzyme showed starch transglycosylation activity over a wide range of NaCl concentrations, with maltotriose as the best acceptor substrate compared to other maltooligosaccharides. This is the first study of an amylomaltase from a halophilic microorganism.

Development of Starch-Based Materials Using Current Modification Techniques and Their Applications: A Review

Starch is one of the most common biodegradable polymers found in nature, and it is widely utilized in the food and beverage, bioplastic industry, paper industry, textile, and biofuel industries. Starch has received significant attention due to its environmental benignity, easy fabrication, relative abundance, non-toxicity, and biodegradability. However, native starch cannot be directly used due to its poor thermo-mechanical properties and higher water absorptivity. Therefore, native starch needs to be modified before its use. Major starch modification techniques include genetic, enzymatic, physical, and chemical. Among those, chemical modification techniques are widely employed in industries. This review presents comprehensive coverage of chemical starch modification techniques and genetic, enzymatic, and physical methods developed over the past few years. In addition, the current applications of chemically modified starch in the fields of packaging, adhesives, pharmaceuticals, agriculture, superabsorbent and wastewater treatment have also been discussed.

Engineering Properties of Sweet Potato Starch for Industrial Applications by Biotechnological Techniques including Genome Editing

Sweet potato (Ipomoea batatas) is one of the largest food crops in the world. Due to its abundance of starch, sweet potato is a valuable ingredient in food derivatives, dietary supplements, and industrial raw materials. In addition, due to its ability to adapt to a wide range of harsh climate and soil conditions, sweet potato is a crop that copes well with the environmental stresses caused by climate change. However, due to the complexity of the sweet potato genome and the long breeding cycle, our ability to modify sweet potato starch is limited. In this review, we cover the recent development in sweet potato breeding, understanding of starch properties, and the progress in sweet potato genomics. We describe the applicational values of sweet potato starch in food, industrial products, and biofuel, in addition to the effects of starch properties in different industrial applications. We also explore the possibility of manipulating starch properties through biotechnological means, such as the CRISPR/Cas-based genome editing. The ability to target the genome with precision provides new opportunities for reducing breeding time, increasing yield, and optimizing the starch properties of sweet potatoes.

GtfC Enzyme of Geobacillus sp. 12AMOR1 Represents a Novel Thermostable Type of GH70 4,6-α-Glucanotransferase That Synthesizes a Linear Alternating (α1 → 6)/(α1 → 4) α-Glucan and Delays Bread Staling

Starch-acting α-glucanotransferase enzymes are of great interest for applications in the food industry. In previous work, we have characterized various 4,6- and 4,3-α-glucanotransferases of the glycosyl hydrolase (GH) family 70 (subfamily GtfB), synthesizing linear or branched α-glucans. Thus far, GtfB enzymes have only been identified in mesophilic Lactobacilli. Database searches showed that related GtfC enzymes occur in Gram-positive bacteria of the genera Exiguobacterium, Bacillus, and Geobacillus, adapted to growth at more extreme temperatures. Here, we report characteristics of the Geobacillus sp. 12AMOR1 GtfC enzyme, with an optimal reaction temperature of 60 °C and a melting temperature of 68 °C, allowing starch conversions at relatively high temperatures. This thermostable 4,6-α-glucanotransferase has a novel product specificity, cleaving off predominantly maltose units from amylose, attaching them with an (α1 → 6)-linkage to acceptor substrates. In fact, this GtfC represents a novel maltogenic α-amylase. Detailed structural characterization of its starch-derived α-glucan products revealed that it yielded a unique polymer with alternating (α1 → 6)/(α1 → 4)-linked glucose units but without branches. Notably, this Geobacillus sp. 12AMOR1 GtfC enzyme showed clear antistaling effects in bread bakery products.

Characterization of gluten-free rice bread prepared using a combination of potato tuber and ramie leaf enzymes

A combination of freeze-dried powder of disproportionating enzyme (D-enzyme)-containing potato tuber and β-amylase-containing ramie leaf was used to improve the gluten-free (GF) bread, and its physicochemical properties were characterized. The presence of D-enzyme and β amylase in the potato tuber and ramie leaf was confirmed. Sixty five percent of partially gelatinized rice flour and 20% corn starch was combined with 10% freeze-dried potato tuber and 1% ramie leaf powder, and baked. The specific volume increased by 23% compared to the control with improved internal characteristics. Texture profile analysis revealed that retrogradation of the bread was retarded when stored for 90 h at 4 °C. The bread crumb amylose content was reduced from 14 to 9% and amylopectin branch chain-length distribution was rearranged, whereby the proportions of the branch chains with Degree of polymerization (DP) < 9 and DP > 19 decreased. The results suggest that D-enzyme and β-amylase cooperatively altered amylose/amylopectin ratio and amylopectin structure.

Impact of thermo-sonication on quality indices of starch-based sauces

In this study, ultrasonication, a physical, relatively cheap, and environmentally benign technology, was investigated to characterize its effect on functional properties of rice starch and rice starch-based sauces. Temperature-assisted ultrasound treatment improved the granular swelling power, fat and water absorption capacities, and thermal properties of rice starch, signifying its suitability in the formulation of starch-based sauces. Rheological characterization of the formulated sauces revealed a shear-thinning flow behavior, well described by the Ostwald de Waele model, while viscoelastic properties showed the existence of a weak gel. Results indicated that ultrasonication significantly enhanced the pseudoplastic behavior of starch-based sauces. Additionally, textural analysis showed that textural attributes (stickiness, stringiness, and work of adhesion) were also improved with ultrasonication. Moreover, enhanced freeze/thaw stability was also achieved with ultrasound-treated starch-based sauces. Overall, the results from this study show that ultrasound-treated starches can be used in the formulation of sauces and potentially other food products, which meets the requirements for clean label and minimally processed foods.

Characteristics of wheat starch-pectin hydrolysate complexes by dry heat treatment

The objective of this study was to characterize dry heat-induced wheat starch-pectin hydrolysate (WST/PH) complexes to develop the retrogradation-retarded starch. Native (N-) and protease-treated (P-) WST were used as starch sources. Pectin hydrolysates were mixed independently with N-WST and P-WST to a mixing ratio of 49:1 (based on total solid contents), followed by drying below 10% moisture and dry heat treatment at 130 °C for 4 h. The molar degrees of substitution (MS) was higher for WST/PH complexes than its mixtures, and apparent amylose contents decreased with their MS. Relative to WST/PH mixtures, solubilities were higher for WST/PH complexes, while swelling powers didn't differ. WST/PH complexes showed the lower degree of retrogradation, setback viscosities, slowly gelling tendency, and syneresis. These phenomena were more pronounced in WST/PH mixtures and complexes prepared with P-WST. Overall results suggest that dry heat-induced WST/PH complexes could be a potential retrogradation-retarded starch to replace chemically-modified starches.

Effects of germination time and kilning temperature on the malting characteristics, biochemical and structural properties of HomChaiya rice

Effects of germination time (3, 5 and 7 days) and kilning temperature (40, 50 and 60 °C) on the malting characteristics, biochemical properties and structural properties of HomChaiya rice were examined. Malting potential in terms of germination rate and germination capacity increased as the germination period of rice was prolonged. Diastatic potential, hot water extract and malting loss of rice gradually increased with germination time and with kilning temperature; in contrast, malting yield and viscosity of the samples decreased. Germination time significantly increased the α-amylase activity, but β-amylase activities increased when kilned at different temperatures. Total starch decreased and reducing sugar increased in rice with prolonged germination, and furthermore, the kilning temperature significantly influenced these changes. Higher kilning temperature and prolonged germination period increased the protease activity in rice, and consequently, soluble protein and free amino acids also increased. Among the twelve identified amino acids in the HomChaiya rice, aspartic acid, glutamic acid, asparagine, serine, arginine, isoleucine, tyrosine, and phenylalanine increased with germination time and kilning temperature. FTIR results showed that increased germination time and kilning temperature unfolded the carbohydrates, which is consistent with the enzymatic (α- and β-amylase) activities. XRD results also found higher peak intensities for rice when germinated longer and kilned at a higher temperature. The crystallinity of malted rice decreased with germination time. Ultrastructural changes showed that starch granules are more vulnerable to enzymatic attack upon extended germination time and at higher kilning temperatures.

Effects of germination time (3, 5 and 7 days) and kilning temperature (40, 50 and 60 °C) on the malting characteristics, biochemical properties and structural properties of HomChaiya rice were examined.

State-of-the-art strategies and applied perspectives of enzyme biocatalysis in food sector - current status and future trends

With the recent progress in biotechnology, a wide variety of novel enzymes with unique physicochemical properties and diverse applications has been introduced, and new application list continues to extend in the future. Enzymes obtained from microorganisms, including bacteria, fungi, yeast are widely applied in numerous food formulations for intensifying their texture and taste. Owing to several desirable characteristics such as easy, cost-efficient and stable production, microbial-derived enzymes are preferred source in contrast to animals or plants. Enzymatic processes have a considerable impact in controlling the characteristics such as (1) physiochemical properties, (2) rheological functionalities, (3) facile process as compared to the chemical-based processing, (4) no or minimal consumption of harsh chemicals, (5) overall cost-effective ratio, (6) sensory and flavor qualities, and (7) intensifying the stability, shelf life and overall quality of the product, etc. in the food industry. Also, enzyme-catalyzed processing has also been designed for new food applications such as extraction of bioactive compounds, nutrient-rich and texture improved foods production, and eliminating food safety hazards. Herein, we reviewed recent applications of food-processing enzymes and highlighted promising technologies to diversify their application range in food industries. Immobilization technology enabled biocatalysts to be used cost-effectively due to reusability with negligible or no activity loss. Integrated progress in novel enzyme discovery, and recombinant DNA technology, as well as protein engineering and bioprocess engineering strategies, are believed to rapidly propagate biocatalysis at industrial-scale food processing or green and sustainable chemical manufacturing.

Physicochemical and Morphological Characterization of Potato Starch Modified by Bacterial Amylases for Food Industry Applications

Two multienzyme bacterial preparations of α-amylase of Bacillus licheniformis and Amylosubtilin® were used in order to modify potato starch at various enzyme concentrations. Eight types of starch were obtained, and their morphological, functional, and physical and chemical characteristics were studied. Induction of enzyme preparations allowed obtaining starches characterized by extended solubility and water-sorption ability and also lower gelation temperatures and viscosity. It was found that studied amylolytic preparations do have different effects on starch granules, despite the identical major amylase activities. The combination of the characteristics studied in the enzymatically modified starches makes them promising for the use as a component of food systems requiring the corrections of their textural features.

Multidisciplinary involvement and potential of thermophiles

The full biotechnological exploitation of thermostable enzymes in industrial processes is necessary for their commercial interest and industrious value. The heat-tolerant and heat-resistant enzymes are a key for efficient and cost-effective translation of substrates into useful products for commercial applications. The thermophilic, hyperthermophilic, and microorganisms adapted to extreme temperatures (i.e., low-temperature lovers or psychrophiles) are a rich source of thermostable enzymes with broad-ranging thermal properties, which have structural and functional stability to underpin a variety of technologies. These enzymes are under scrutiny for their great biotechnological potential. Temperature is one of the most critical parameters that shape microorganisms and their biomolecules for stability under harsh environmental conditions. This review describes in detail the sources of thermophiles and thermostable enzymes from prokaryotes and eukaryotes (microbial cell factories). Furthermore, the review critically examines perspectives to improve modern biocatalysts, its production and performance aiming to increase their value for biotechnology through higher standards, specificity, resistance, lowing costs, etc. These thermostable and thermally adapted extremophilic enzymes have been used in a wide range of industries that span all six enzyme classes. Thus, in particular, target of this review paper is to show the possibility of both high-value-low-volume (e.g., fine-chemical synthesis) and low-value-high-volume by-products (e.g., fuels) by minimizing changes to current industrial processes.