Physicochemical, structural, and digestibility properties of enzymatic modified plantain and mango starches

Exploring differences in the physicochemical and nutritional properties of mango flours and starches

Mangoes contain several components that are beneficial for health, in addition to being potential sources of starch for the food industry. However, a substantial amount of fruit is lost in the field because it does not meet commercial standards, resulting in food losses and environmental damage. Herein, the physicochemical properties of mango flours and starches obtained from different parts of the fruit of two cultivars were evaluated. Mango peel flours have higher levels of proteins, fibers, minerals, carotenoids, ascorbic acid, and antioxidant activity than pulp flours, in addition to a higher yellowing index and water and oil-holding capacity, and can be used as a functional flour. The pulp flours, with the higher starch content, showed characteristics that make them valuable as a potential ingredient in soft baking and gluten-free products. Mango starches have circular and oval shapes, with a bimodal distribution. All starches showed an A-type crystallinity pattern. Pulp starches showed a higher peak viscosity and breakdown, with a lower setback, and can be used as a thickening or gelling agent. The higher thermal stability of kernel starch suggests its application in sauces, baking, dairy products, and canned foods.

Slowly digestible property of highly branched α-limit dextrins produced by 4,6-α-glucanotransferase from Streptococcus thermophilus evaluated in vitro and in vivo

Starch molecules are first degraded to slowly digestible α-limit dextrins (α-LDx) and rapidly hydrolyzable linear malto-oligosaccharides (LMOs) by salivary and pancreatic α-amylases. In this study, we designed a slowly digestible highly branched α-LDx with maximized α-1,6 linkages using 4,6-α-glucanotransferase (4,6-αGT), which creates a short length of α-1,4 side chains with increasing branching points. The results showed that a short length of external chains mainly composed of 1-8 glucosyl units was newly synthesized in different amylose contents of corn starches, and the α-1,6 linkage ratio of branched α-LDx after the chromatographical purification was significantly increased from 4.6% to 22.1%. Both in vitro and in vivo studies confirmed that enzymatically modified α-LDx had improved slowly digestible properties and extended glycemic responses. Therefore, 4,6-αGT treatment enhanced the slowly digestible properties of highly branched α-LDx and promises usefulness as a functional ingredient to attenuate postprandial glucose homeostasis.

Starch digestibility: past, present, and future

In the last century, starch present in foods was considered to be completely digested. However, during the 1980s, studies on starch digestion started to show that besides digestible starch, which could be rapidly or slowly hydrolysed, there was a variable fraction that resisted hydrolysis by digestive enzymes. That fraction was named resistant starch (RS) and it encompasses those forms of starch that are not accessible to human digestive enzymes but can be fermented by the colonic microbiota, producing short-chain fatty acids. RS has been classified into five types, depending on the mechanism governing its resistance to enzymatic hydrolysis. Early research on RS was focused on the methods to determine its content in foods and its physiological effects, including fermentability in the large intestine. Later on, due to the interest of the food industry, methods to increase the RS content of isolated starches were developed. Nowadays, the influence of RS on the gut microbiota is a relevant research topic owing to its potential health-related benefits. This review summarizes over 30 years of investigation on starch digestibility, its relationship with human health, the methods to produce RS and its impact on the microbiome. © 2018 Society of Chemical Industry.

Versatile biotechnological applications of amylosucrase, a novel glucosyltransferase

Amylosucrase (AS; EC 2.4.1.4) is an enzyme that has great potential in the biotechnology and food industries, due to its multifunctional enzyme activities. It can synthesize α-1,4-glucans, like amylose, from sucrose as a sole substrate, but importantly, it can also utilize various other molecules as acceptors. In addition, AS produces sucrose isomers such as turanose and trehalulose. It also efficiently synthesizes modified starch with increased ratios of slow digestive starch and resistant starch, and glucosylated functional compounds with increased water solubility and stability. Furthermore, AS produces turnaose more efficiently than other carbohydrate-active enzymes. Amylose synthesized by AS forms microparticles and these can be utilized as biocompatible materials with various bio-applications, including drug delivery, chromatography, and bioanalytical sciences. This review not only compares the gene and enzyme characteristics of microbial AS, studied to date, but also focuses on the applications of AS in the biotechnology and food industries.

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.

Physicochemical, digestibility and structural characteristics of starch isolated from banana cultivars

Banana starches from diverse varieties (Macho, Morado, Valery and Enano Gigante) were studied in their physicochemical, structural and digestibility features. X-ray diffraction indicated that the banana starches present a B-type crystallinity pattern, with slight difference in the crystallinity level. Macho and Enano Gigante starches showed the highest pasting temperatures (79 and 78°C, respectively), whilst Valery and Morado varieties presented a slight breakdown and higher setback than the formers. Morado starch presented the highest solubility value and Valery starch the lowest one. The swelling pattern of the banana starches was in agreement with their pasting profile. All banana starches showed a shear-thinning profile. The resistant starch (RS) fraction was the main fraction in the uncooked banana starches. Morado variety showed the highest amount of slowly digestible starch (SDS) and the lowest RS content reported until now in banana starches. Banana starch cooked samples presented an important amount of SDS and RS. Molecular weight and gyration radius of the four banana starches ranged between 2.88-3.14×10(8)g/mol and 286-302nm, respectively. The chain-length distributions of banana amylopectin showed that B1 chains (DP 13-24) is the main fraction, and an important amount of long chains (DP≥37) are present. The information generated from this study can be useful to determine banana varieties for starch isolation with specific functionality.

Pea starch (Pisum sativum L.) with slow digestion property produced using β-amylase and transglucosidase

Starches extracted from wrinkled (WP) and smooth (SP) peas were treated using β-amylase (B) alone and also with a combination of β-amylase and transglucosidase (BT). After enzymatic treatment, the proportions of slowly digested starch in WP-B, WP-BT, SP-B and SP-BT samples were increased by 6%, 9%, 9% and 12%, respectively. Starches treated by a combination of β-amylase and transglucosidase exhibited a smaller amount of longer amylopectin chains, a larger amount of short amylopectin chains, and higher branching fraction. The branching fraction was significantly increased, with an increase of 8%, 10%, 13% and 14% for WP-B, WP-BT, SP-B and SP-BT, respectively. The maximum absorbance and iodine binding of enzyme-treated starches were reduced compared with their native starch parents. The C-type crystalline structure completely disappeared after enzymatic treatment. The results support previous findings that increases in the amount of shorter amylopectin chains and branch fraction are likely to contribute to the slow digestion of starch.

Slow glucose release property of enzyme-synthesized highly branched maltodextrins differs among starch sources

Seven types of starch (waxy corn, normal corn, waxy rice, normal rice, waxy potato, normal potato, and tapioca) were selected to produce slowly digestible maltodextrins by enzymatic modification using a previously developed procedure. Branching enzyme (BE) alone and in combination with β-amylase (BA) were used to increase the amount of α-1,6 branching points, which are slowly hydrolyzed by mucosal α-glucosidases in the small intestine. The enzymatic treatments of all starches resulted in a reduction of the debranched linear chain length distribution and weight-average molecular weight. After α-amylolysis of the enzymatically synthesized-maltodextrins, the proportion of branched α-limit dextrins increased, and consequently a reduction in rate of glucose release by rat intestinal α-glucosidases in vitro. Among the samples, enzyme-modified waxy starches had a more pronounced effect on an increase in the slow digestion property than normal starches. These enzyme-modified maltodextrins show potential as novel functional foods by slowing digestion rate to attain extended glucose release.

In vitro digestibility, physicochemical, thermal and rheological properties of banana starches

Banana starches (BS) were isolated from Enano, Morado, Valery and Macho cultivars. The BS possessed B-type crystallinity and an amylose content varying from 19.32 to 26.35%. Granules had an oval morphology with different major-to-minor axis ratios, exhibiting both mono- and bi-modal distributions and mean particle sizes varying from 32.5 to 45 μm. BS displayed zeta-potential values ranging between -32.25 and -17.32 mV, and formed gels of incipient to moderate stability. The enthalpy of gelatinization of BS affected the crystalline order stability within the granules. In-vitro digestibility tests showed fractions as high as 68% of resistant starch. Rheological oscillatory tests at 1 Hz showed that BS dispersions (7.0%, w/w) exhibited Type III behaviour, attributed to the formation of a continuous phase complex three-dimensional amylose gel reinforced by swollen starch granules acting as fillers. Amylose content and granules morphology were the main factors influencing the BS properties.