Tailoring the formulation of sugar-snap cookies to lower in vitro starch digestibility: A response surface modelling approach

An I-optimal response surface experimental design revealed impacts of dough moisture content (DMC, 14-22%) and level of wheat flour substitution (10-50%) by wheat gluten and one of six different native starches [wheat, (waxy) maize, rice, potato, pea] on sugar-snap cookie starch thermal properties, in vitro starch digestion, dough and cookie hardness and spread ratio. Increasing DMCs from 14 to 22% increased the cookie starch digestion rate constants of each starch source used. A linear increase of the constant by 25-30% across the 14 to 22% DMC range for all starches was predicted and validated. That cookie spread and hardness were related to the water retention capacity of the native starches used suggested that they underwent limited changes during baking. For each starch examined, formulations were optimized to lower in vitro starch digestion rate and extent, and cookie hardness, while maximizing dough spread ratio.

Varying precipitation conditions allow directing the composition and physical properties of soy protein concentrates

Soy protein concentrates (SPCs) are common food ingredients. They typically contain 65% (w/w) protein and ∼30% (w/w) carbohydrate. SPCs can be obtained with various protein precipitation conditions. A systematic study of the impact of these different protein precipitation protocols on the SPC protein composition and physical properties is still lacking. Here, SPCs were prepared via three different protocols, that is, isoelectric (pH 3.5-5.5), aqueous ethanol (50%-70% [v/v]), and Ca2+ ion (5-50 mM) based precipitations, and analyzed for (protein) composition, protein thermal properties, dispersibility, and water-holding capacity. SPCs precipitated at pH 5.5 or by adding 15 mM Ca2+ ions had a lower 7S/11S globulin ratio (∼0.40) than that (∼0.50) of all other SPC samples. Protein in SPCs obtained by isoelectric precipitation denatured at a significantly higher temperature than those in ethanol- or Ca2+ -precipitated SPCs. Precipitation with 50%-60% (v/v) ethanol resulted in pronounced denaturation of 2S albumin and 7S globulin fractions in SPCs. Additionally, increasing the precipitation pH from 3.5 to 5.5 and increasing the Ca2+ ion concentration from 15 to 50 mM caused a strong decrease of both the dispersibility of the protein in SPC and its water-holding capacity at pH 7.0. In conclusion, this study demonstrates that the SPC production process can be directed to obtain ingredients with versatile protein physicochemical properties toward potential food applications. PRACTICAL APPLICATION: This study demonstrates that applying different protein precipitation protocols allows obtaining SPCs that vary widely in (protein) composition and physical properties (such as protein dispersibility and water-holding capacity). These varying traits can greatly influence the suitability of SPCs as functional ingredients for specific applications, such as the production of food foams, emulsions, gels, and plant-based meat alternatives. The generated knowledge may allow targeted production of SPCs for specific applications.

Hydrothermal treatments of starch impact reaction patterns during subsequent chemical derivatization

Differences in derivatization patterns (using a fluorescent reagent, fluorescein isothiocyanate) of wheat, pea, and potato starches between native granular (NAT) starches and their respective annealed (ANN) and heat-moisture treated (HMT) starches were investigated to reveal structural changes associated with starch hydrothermal treatments. Size-exclusion chromatography with fluorescence and refractive index detection assessed the reactivity of amylose (AM), intermediate chains (IM1 and IM2), and amylopectin branch chains (AP1, AP2, and AP3) within the different starches. Shifts in X-ray diffraction patterns of HMT starches and in the gelatinization properties of both ANN and HMT starches confirmed molecular rearrangement. The reaction homogeneity (wheat and pea) and the overall extent of reaction (pea and potato) increased for HMT starches compared to other starches. The lower reactivities of IM2 chains (HMT starch) and AP3 chains (ANN starch) relative to NAT starches, indicated their involvement in molecular rearrangements and improved double helical order. IM2 and AP branch chains in ANN pea starch also were less reacted than NAT starch chains, suggesting their co-crystallization. Molecular rearrangements in ANN and HMT starches led to altered swelling and pasting viscosities. Thus, changes in the relative crystallinity of individual starch branch chains induced by hydrothermal processing impact the final physical properties.

Sucrose substitution in cake systems is not a piece of cake

Successful sucrose replacement in cake systems requires thorough understanding of its functionality. Time-domain 1H NMR showed that water in the viscous aqueous phase isolated from cake batter by ultracentrifugation [i.e. the batter liquor (BL)] exhibits low mobility by its low T2 relaxation time (T2,D RT). This is due to its interactions with sucrose or sucrose replacers. The T2,D RT itself is positively related with the effective volumetric hydrogen bond density of sucrose or sucrose replacers. Sucrose additionally co-determines the quantity and viscosity of cake BL and thereby how much air the batter contains at the end of mixing. Like sucrose, maltitol and oligofructose provide adequate volumes of BL with low water mobility and thus sufficient air in the batter, while the rather insoluble mannitol and inulin do not. Differential scanning calorimetry and rapid viscosity analysis revealed, however, that, in contrast to sucrose and maltitol, oligofructose fails to provide appropriate timings of starch gelatinisation and protein denaturation, resulting in poor cake texture. The shortcomings of mannitol and oligofructose in terms of respectively ensuring appropriate gas content in batter and biopolymer transitions during baking can be overcome by using mixtures thereof. This work shows that successful sucrose substitutes or substitute mixtures must provide sufficient BL with low water mobility and ensure appropriate timings of starch and protein biopolymer transitions during baking.

Promotion of starch retrogradation by enzymatic elongation of amylopectin chains does not reduce glycemic responses: a randomized cross-over clinical trial

The molecular structure of amylopectin (AP) governs the propensity of its chains to re-associate into crystalline arrangements after starch gelatinization. Amylose (AM) crystallization and AP re-crystallization (i.e. retrogradation) decrease starch digestibility. The aim of this work was to enzymatically elongate AP chains using an amylomaltase (AMM, i.e. 4-α-glucanotransferase) from Thermus thermophilus to promote AP retrogradation and to investigate the impact thereof on in vivo glycemic responses in healthy subjects. Participants (n = 32) consumed two oatmeal porridges (containing 22.5 g available carbohydrates) prepared with or without the enzymatic modification and stored at 4 °C for 24 h. Finger-prick blood samples were taken fasting and at intervals during 3 h following test-meal consumption. The incremental area under the curve (iAUC_0-180) was determined. The AMM was very effective at elongating the AP chains at the expense of AM, resulting in increased retrogradation capacity upon storage at low temperature. Nevertheless, postprandial glycemic responses were not different after consumption of either the AMM modified oatmeal porridge or its unmodified counterpart (iAUC_0-180 = 73 ± 30 vs. 82 ± 43 mmol min L^-1, respectively; p = 0.17). Unexpectedly, promoting starch retrogradation by selectively modifying its molecular structure did not result in reduced glycemic responses, challenging the notion that starch retrogradation negatively impacts glycemic responses in vivo.

Olive-Derived Antioxidant Dietary Fiber Modulates Gut Microbiota Composition and Attenuates Atopic Dermatitis Like Inflammation in Mice

SCOPE

Epidemiological data suggest that altered gut microbiota contributes to the development of atopic dermatitis (AD). The effect of an olive-derived antioxidant dietary fiber (OADF) in relieving AD symptoms in a murine model of 2,4-dinitrofluorobenzene (DNFB)-induced AD was examined and the effect of OADF in modulating host gut microbiota was explored.

METHODS AND RESULTS

Mice were fed with either standard diet or standard diet + OADF for 3 weeks prior to induction of AD and maintained on the same diet throughout the DNFB application period. Dietary OADF caused significant improvement of AD-like symptoms with reduced serum levels of IgE, IL-1β, IL-6, CXCL1 and increased serum levels of IL-10. OADF supplementation restored gut microbiota composition that were altered in AD mice. Specifically, OADF increased the proportion of intestinal bacteria (Ruminococcaceae UCG014, GCA900066575, UBA1819) associated with enhanced butyrate production, along with inhibiting Clostridiales vadinBB60 which were more prevalent in AD mice.

CONCLUSION

OADF modulates gut microbiota composition, improves cytokine profile and butyrate production influencing AD-associated immune response. Results highlight the importance of the gut-skin axis for the AD dietary therapeutic agents. This article is protected by copyright. All rights reserved.

The use of time domain 1 H NMR to study proton dynamics in starch-rich foods: A review

Starch is a major contributor to the carbohydrate portion of our diet. When it is present with water, it undergoes several transformations during heating and/or cooling making it an essential structure-forming component in starch-rich food systems (e.g., bread and cake). Time domain proton nuclear magnetic resonance (TD ¹ H NMR) is a useful technique to study starch-water interactions by evaluation of molecular mobility and water distribution. The data obtained correspond to changes in starch structure and the state of water during or resulting from processing. When this technique was first applied to starch(-rich) foods, significant challenges were encountered during data interpretation of complex food systems (e.g., cake or biscuit) due to the presence of multiple constituents (proteins, carbohydrates, lipids, etc.). This article discusses the principles of TD ¹ H NMR and the tools applied that improved characterization and interpretation of TD NMR data. More in particular, the major differences in proton distribution of various dough and cooked/baked food systems are examined. The application of variable-temperature TD ¹ H NMR is also discussed as it demonstrates exceptional ability to elucidate the molecular dynamics of starch transitions (e.g., gelatinization, gelation) in dough/batter systems during heating/cooling. In conclusion, TD NMR is considered a valuable tool to understand the behavior of starch and water that relate to the characteristics and/or quality of starchy food products. Such insights are crucial for food product optimization and development in response to the needs of the food industry.

Hydration of Wheat Flour Water-Unextractable Cell Wall Material Enables Structural Analysis of Its Arabinoxylan by High-Resolution Solid-State 13C MAS NMR Spectroscopy

To enable its structural characterization by nuclear magnetic resonance (NMR) spectroscopy, the native structure of cereal water-unextractable arabinoxylan (WU-AX) is typically disrupted by alkali or enzymatic treatments. Here, WU-AX in the wheat flour unextractable cell wall material (UCWM) containing 40.9% ± 1.5 arabinoxylan with an arabinose-to-xylose ratio of 0.62 ± 0.04 was characterized by high-resolution solid-state NMR without disrupting its native structure. Hydration of the UCWM (1.7 mg H₂O/mg UCWM) in combination with specific optimizations in the NMR methodology enabled analysis by solid-state ¹³C NMR with magic angle spinning and ¹H high-power decoupling (¹³C HPDEC MAS NMR) which provided sufficiently high resolution to allow for carbon atom assignments. Spectral resonances of C-1 from arabinose and xylose residues of WU-AX were here assigned to the solid state. The proportions of un-, mono-, and di-substituted xyloses were 59.2, 19.5, and 21.2%, respectively. ¹³C HPDEC MAS NMR showed the presence of solid-state fractions with different mobilities in the UCWM. This study presents the first solid-state NMR spectrum of wheat WU-AX with sufficient resolution to enable assignment without prior WU-AX solubilization.

Investigating the Sequence Determinants of the Curling of Amyloid Fibrils Using Ovalbumin as a Case Study

Highly ordered, straight amyloid fibrils readily lend themselves to structure determination techniques and have therefore been extensively characterized. However, the less ordered curly fibrils remain relatively understudied, and the structural organization underlying their specific characteristics remains poorly understood. We found that the exemplary curly fibril-forming protein ovalbumin contains multiple aggregation prone regions (APRs) that form straight fibrils when isolated as peptides or when excised from the full-length protein through hydrolysis. In the context of the intact full-length protein, however, the regions separating the APRs facilitate curly fibril formation. In fact, a meta-analysis of previously reported curly fibril-forming proteins shows that their inter-APRs are significantly longer and more hydrophobic when compared to straight fibril-forming proteins, suggesting that they may cause strain in the amyloid state. Hence, inter-APRs driving curly fibril formation may not only apply to our model protein but rather constitute a more general mechanism.

Heat-induced denaturation and aggregation of protein in quinoa (Chenopodium quinoa Willd.) seeds and whole meal

Physical barriers hinder about 20-25% of the protein from being extracted from whole meal. Heat-induced denaturation and aggregation of protein in quinoa seeds and in whole meal was investigated. Maximally 37% of the protein in seeds covalently aggregate when boiling for 15 min. Although embryonic cell walls surrounding protein bodies remain intact during boiling of seeds, protein aggregation is not hindered. 11S Globulin monomers first dissociate into their acidic and basic subunits which further assemble into large (> 500 kDa) mainly disulfide-linked aggregates. 2S Albumins are not involved in covalent aggregation but partially leach during seed boiling. The presence of disrupted food matrix constituents in whole meal delays denaturation and causes less aggregation of protein in whole meal than in seeds. Globulins still dissociate into their subunits but less and mainly small covalent aggregates (ca. 100-500 kDa) are formed. These novel insights allow developing new quinoa-based food products.

Structural factors governing starch digestion and glycemic responses and how they can be modified by enzymatic approaches: A review and a guide

Starch is the most abundant glycemic carbohydrate in the human diet. Consumption of starch-rich food products that elicit high glycemic responses has been linked to the occurrence of noncommunicable diseases such as cardiovascular disease and diabetes mellitus type II. Understanding the structural features that govern starch digestibility is a prerequisite for developing strategies to mitigate any negative health implications it may have. Here, we review the aspects of the fine molecular structure that in native, gelatinized, and gelled/retrograded starch directly impact its digestibility and thus human health. We next provide an informed guidance for lowering its digestibility by using specific enzymes tailoring its molecular and three-dimensional supramolecular structure. We finally discuss in vivo studies of the glycemic responses to enzymatically modified starches and relevant food applications. Overall, structure-digestibility relationships provide opportunities for targeted modification of starch during food production and improving the nutritional profile of starchy foods.

Gas cell stabilization by aqueous-phase constituents during bread production from wheat and rye dough and oat batter: Dough or batter liquor as model system

Proper gas cell stability during fermentation and baking is essential to obtain high-quality bread. Gas cells in wheat dough are stabilized by the gluten network formed during kneading and, from the moment this network locally ruptures, by liquid films containing nonstarch polysaccharides (NSPs) and surface-active proteins and lipids. Dough liquor (DL), the supernatant after ultracentrifugation of dough, is a model system for these liquid films and has been extensively studied mostly in the context of wheat bread making. Nonwheat breads are often of lower quality (loaf volume and crumb structure) than wheat breads because their doughs/batters lack a viscoelastic wheat gluten network. Therefore, gas cell stabilization by liquid film constituents may be more important in nonwheat than in wheat bread making. This manuscript aims to review the knowledge on DL/batter liquor (BL) and its relevance for studying gas cell stabilization in wheat and nonwheat (rye and oat) bread making. To this end, the unit operations in wheat, rye, and oat bread making are described with emphasis on gas incorporation and gas cell (de)stabilization. A discussion of the knowledge on the recoveries and chemical structures of proteins, lipids, and NSPs in DLs/BLs is provided and key findings of studies dealing with foaming and air-water interfacial properties of DL/BL are discussed. Next, the extent to which DL/BL functionality can be related to bread properties is addressed. Finally, the extent to which DL/BL is a representative model system for the aqueous phase of dough/batter is discussed and related to knowledge gaps and further research opportunities.

Investigation of starch functionality and digestibility in white wheat bread produced from a recipe containing added maltogenic amylase or amylomaltase

In the crumb of fresh white wheat bread, starch is fully gelatinized. Its molecular and three-dimensional structure are major factors limiting the rate of its digestion. The aim of this study was to in situ modify starch during bread making with starch-modifying enzymes (maltogenic amylase and amylomaltase) and to investigate the impact thereof on bread characteristics, starch retrogradation and digestibility. Maltogenic amylase treatment increased the relative content of short amylopectin chains (degree of polymerization ≤ 8). This resulted in lower starch retrogradation and crumb firmness upon storage, and reduced extent (up to 18%) of in vitro starch digestion for fresh and stored breads. Amylomaltase only modestly shortened amylose chains and had no measurable impact on amylopectin structure. Modification with this enzyme led to slower bread crumb firming but did not influence starch digestibility.

1H Diffusion-Ordered Nuclear Magnetic Resonance Spectroscopic Analysis of Water-Extractable Arabinoxylan in Wheat (Triticum aestivum L.) Flour

The structural heterogeneity of water-extractable arabinoxylan (WE-AX) impacts wheat flour functionality. ¹H diffusion-ordered (DOSY) nuclear magnetic resonance (NMR) spectroscopy revealed structural heterogeneity within WE-AX fractions obtained via graded ethanol precipitation. Combination with high-resolution ¹H-¹H correlation NMR spectroscopy (COSY) allowed identifying the relationship between the xylose substitution patterns and diffusion properties of the subpopulations. WE-AX fractions contained distinct subpopulations with different diffusion rates. WE-AX subpopulations with a high self-diffusivity contained high levels of monosubstituted xylose. In contrast, those with a low self-diffusivity were rich in disubstituted xylose, suggesting that disubstitution mainly occurs in WE-AX molecules with large hydrodynamic volumes. In general, WE-AX fractions precipitating at higher and lower ethanol concentrations had higher and lower self-diffusivity and more and less complex substitution patterns. Although ¹H DOSY NMR, as performed in this study, was valuable for elucidating WE-AX structural heterogeneity, physical limitations arose when studying WE-AX populations with high molecular weight dispersions.

Free wheat flour lipids decrease air-liquid interface stability in sponge cake batter

The impact of free wheat flour lipids on air-liquid interface stability during sponge cake making was investigated. Therefore, the molecular population at the air-liquid interface in batters prepared with flour of which part of the lipids had been either relocated or removed prior to batter preparation was determined. Surface-active molecules were isolated from batter using a foam separation protocol. Diluted batter was whipped and the resulting foam was used as model system for the air-liquid interface in sponge cake batter. Relocating flour lipids prior to batter making enabled them to adsorb at the air-liquid interface in the foam. This limited the degree of protein adsorption at the air-liquid interface, but it did not impact the composition of the adsorbed protein population. Removing flour lipids prior to batter making resulted in foam containing relatively higher levels of lipids mainly originating from egg yolk. Prior removal of flour lipids impacted neither foam protein content nor foam protein composition. The resultant molecular population improved air-liquid interface stability in sponge cake batter. Thus, free wheat flour lipids and wheat flour lipids set free by solvent treatment decrease air-liquid interface stability in sponge cake batter mainly because they limit protein adsorption and, as such, interfere with the protein-dominated interface.

Hydrothermal Treatments Cause Wheat Gluten-Derived Peptides to Form Amyloid-like Fibrils

Formation of amyloid fibrils (i.e., protein structures containing a compact core of ordered β-sheet structures) from food proteins can improve their techno-functional properties. Wheat gluten is the most consumed cereal protein by humans and extensively present in food and feed systems. Hydrolysis of wheat gluten increases the solubility of its proteins and brings new opportunities for value creation. In this study, the formation of amyloid-like fibrils (ALFs) from wheat gluten peptides (WGPs) under food relevant processing conditions was investigated. Different hydrothermal treatments were tested to maximize the formation of straight ALFs from WGPs. Thioflavin T (ThT) fluorescence measurements and transmission electron microscopy (TEM) were performed to study the extent of fibrillation and the morphology of the fibrils, respectively. First, the formation of fibrils by heating solutions of tryptic WGPs [degrees of hydrolysis 2.0% (DH 2) or 6.0% (DH 6)] was optimized using a response surface design. WGP solutions were incubated at different pH values, times, and temperatures. DH 6 WGPs had a higher propensity for fibrillation than did DH 2 WGPs. Heating DH 6 WGPs at 2.0% (w/v) for 38 h at 85 °C and pH 7.0 resulted in optimal fibrillation. Second, trypsin, chymotrypsin, thermolysin, papain, and proteinase K were used to produce different DH 6 WGPs. After enzyme inactivation and subsequent heating at optimal fibrillation conditions, chymotrypsin and proteinase K DH 6 WGPs produced small worm-like fibrils, whereas fibrils prepared from trypsin DH 6 WGPs were long and straight. The surface hydrophobicity of the peptides was key for fibrillation. Third, peptides from the wheat gluten components gliadin and glutenin fractions formed smaller and worm-like fibrils than did WGPs. Thus, the peptides of both gluten protein fractions jointly contribute to gluten fibrillation.

Use of Amylomaltase to Steer the Functional and Nutritional Properties of Wheat Starch

The fine molecular structure of starch governs its functionality and digestibility, and enzymatic approaches can be utilized to tailor its properties. The aim of this study was to investigate the in situ modification of starch by amylomaltase (AMM) from Thermus thermophilus in model starch systems subjected to hydrothermal treatments under standardized conditions and the relationship between molecular structure, rheological properties and in vitro digestibility. When low dosages of AMM were added to a wheat starch suspension prior to submitting it to a temperature-time profile in a Rapid Visco Analyzer, the increased peak viscosity observed was attributed to partial depolymerization of amylose, which facilitated starch swelling and viscosity development. At higher dosages, the effect was smaller. The low cold paste viscosity as a result of the activity of AMM reflected substantial amylose depolymerization. At the same time, amylopectin chains were substantially elongated. The longer amylopectin chains were positively correlated (R² = 0.96) with the melting enthalpies of retrograded starches, which, in turn, were negatively correlated with the extent (R² = 0.92) and rate (R² = 0.79) of in vitro digestion. It was concluded that AMM has the potential to be used to deliver novel starch functionalities and enhance its nutritional properties.

Heating Wheat Gluten Promotes the Formation of Amyloid-like Fibrils

Amyloid fibrils (AFs) are highly ordered nanofibers composed of proteins rich in β-sheet structures. In this study, the impact of heating conditions relevant in food processing on AF formation of wheat gluten (WG) was investigated. Unheated and heated WG samples were treated with proteinase K and trypsin to solubilize the nonfibrillated protein, while protein fibrils were extracted with 0.05 M sodium phosphate buffer (pH 7.0) from the undissolved fraction obtained by the same enzymatic treatment. Conditions (i.e., heating at 78° for 22 h) resembling those in slow cooking induced the formation of straight fibrils (ca. 700 nm in length), whereas boiling WG for at least 15 min resulted in longer straight fibrils (ca. 1-2 μm in length). The latter showed the typical green birefringence of AFs when stained with Congo red. Their X-ray fiber diffraction patterns showed the typical reflection (4.7 Å) for inter-β-strand spacing. These results combined with those of Fourier transform infrared and thioflavin T spectroscopy measurements validated the identification of β-rich amyloid-like fibrils (ALFs) in dispersions of boiled WG. Boiling for at least 15 min converted approximately 0.1-0.5% of WG proteins into ALFs, suggesting that they can be present in heat-treated WG-containing food products and that food-relevant heating conditions have the potential to induce protein fibrillation.

The role of exogenous lipids in starch and protein mediated sponge cake structure setting during baking

While it is well established that using exogenous lipids (ELs) such as monoacylglycerols and polyglycerolesters of fatty acids improves gas cell incorporation and stability in sponge cake batter (SCB) and allows producing sponge cakes (SCs) with very high volume, fine grained crumb and soft texture, their impact on starch gelatinization and protein polymerization remained unknown. Here, differential scanning calorimetry and size-exclusion high performance liquid chromatography were performed on SC(B) samples prepared with or without ELs. Starch gelatinization and protein denaturation and polymerization started at temperatures exceeding 67 °C and mostly occurred up to a temperature of 96 °C. During further isothermal treatment at 96 °C the rigidity of the cake matrix (for which temperature-controlled time domain ¹H NMR T₂ relaxation times are a predictor) further increased mainly because of protein polymerization. While the temperature range of starch crystal melting was not affected by the use of ELs, protein polymerized more intensively in an 88 to 94 °C temperature range when SCB contained ELs. The more intense protein polymerization and the high water binding capacity of ELs presumably made the cake matrix more rigid at that point in time. The present results allow concluding that ELs not only impact air-liquid interface stability but also cake structure setting. Hence, both aspects most likely contribute to the superior quality of SCs containing ELs.

Transformations and functional role of starch during potato crisp making: A review

Potato chips are a major product in the savory snack market and are consumed worldwide because of their enjoyable and distinctive organoleptic properties. They are conventionally produced by deep-frying thin slices of fresh potato. In contrast, potato crisps are manufactured from dried potato derivatives such as potato flakes (PFs). Their production is reviewed in this manuscript and requires the formation of dough based on hydrated PFs. Expansion of the dough during deep-frying provides the crisps with their desired crunchy texture. As part of an overall trend, the consumer search for calorie-reduced food products has also stimulated research to lower oil uptake during crisp production. However, minimizing oil absorption without losing the characteristic palatability of deep-fried products is challenging and requires fundamental knowledge on factors determining product texture and oil absorption. The transformations and functional role of starch, potato's main constituent, during crisp making are key in this respect and are reviewed here.

Amylose molecular fine structure dictates water-oil dynamics during deep-frying and the caloric density of potato crisps

The fine structure of extractable amylose (E-AM) in potato flakes dictates oil uptake during the production of deep-fried crisps from dough made from the flakes, and thus their caloric density. High levels of short E-AM chains increase the extent of amylose crystallization during dough making and increase water binding. Time-domain proton NMR analysis showed that they also cause water to be released at a low rate during deep-frying and thus restrict dough expansion and, most importantly, oil uptake. X-ray micro-computed tomography revealed that this results in high thickness of the crisp solid matrix and reduced pore sizes. Thus, the level of short E-AM chains in potato flakes impacts amylose crystal formation, dough strength and expansion, as well as the associated oil uptake during deep-frying. Based on these results, we advise potato crisp manufacturers to source potato cultivars with high levels of short amylose chains for the production of reduced-calorie crisps and to make well-reasoned process adaptations to control the extractability of potato amylose.

Amylose and amylopectin functionality during storage of bread prepared from flour of wheat containing unique starches

Bread crumb firming is largely determined by the properties of gluten and starch, and the transformations they undergo during bread making and storage. Amylose (AM) and amylopectin (AP) functionality in fresh and stored bread was investigated with NMR relaxometry. Bread was prepared from flours containing normal and atypical starches, e.g., flour from wheat line 5-5, with or without the inclusion of Bacillus stearothermophilus α-amylase. Initial crumb firmness increased with higher levels of AM or shorter AM chains. Both less extended AM and gluten networks and too rigid AM networks led to low crumb resilience. AP retrogradation during storage increased when crumb contained more AP or longer AP branch chains. Shorter AP branch chains, which were present at higher levels in 5-5 than in regular bread, were less prone to retrogradation, thereby limiting gluten network dehydration due to gluten to starch moisture migration. Correspondingly, crumb firming in 5-5 bread was restricted.