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.

What makes starch from potato (Solanum tuberosum L.) tubers unique: A review.

The use of starch in food systems in many instances relies on its thickening and gelling capacity. When native starches fail to match process and/or product-specific requirements, starches are physically and/or chemically modified to meet end-use demands. Evidently, differences between starches of varying botanical origin have to be considered when selecting or modifying starches for particular applications. Potato starch (PS) ranks third in world production after maize and wheat starches. Its unique properties differ from those of cereal and pulse starches and are directly related to its molecular structure and organization. This review summarizes the differences between PS and cereal and pulse starches and how they set it apart in terms of gelatinization, pasting, gelation, and retrogradation. Recent advances in improving PS pasting and gelation using enzyme technology and mineral ions are also described.

Ingredient Functionality During Foam-Type Cake Making: A Review.

Foam-type cakes are complex food systems. Their main ingredients are wheat flour, hen eggs, sugar, leavening agent, and, in some cases, oil and/or surfactants. In contrast to the vast amount of research outcomes on the contribution of ingredients to the quality of batter-type cake systems, information on the functionality and importance of the ingredients and their constituents in foam-type cake systems is lacking. This review defines foam-type cakes, describes how they are made, summarizes the current knowledge of factors determining their quality, and identifies the current knowledge gaps.

Ingredient Functionality in Multilayered Dough-margarine Systems and the Resultant Pastry Products: A Review.

Pastry products are produced from heterogeneous multilayered dough systems. The main ingredients are flour, water, fat and sugar for puff pastry, and the same plus yeast for fermented pastry. Key aspects in pastry production are (i) building laminated dough containing alternating layers of dough and bakery fat and (ii) maintaining this multilayered structure during processing to allow for steam entrapment for proper dough lift during baking. Although most authors agree on the importance of gluten and fat for maintaining the integrity of the different layers, detailed studies on their specific function are lacking. The exact mechanism of steam entrapment during dough lift and the relative contribution of water set free from the fat phase during baking also remain unclear. This review brings together current knowledge on pastry products and the factors determining (intermediate) product quality. Its focus is on flour constituents, fat, water, and (where applicable) yeast during the different production stages of pastry products. Future research needs are addressed as the knowledge on biochemical and physical changes occurring in flour constituents and other ingredients during pastry production and their effect on product quality is currently inadequate.

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.

The influence of varying levels of molecular oxygen on the functionality of azodicarbonamide and ascorbic acid during wheat bread making.

Air, and thus also molecular oxygen (O2), is incorporated in wheat flour dough during mixing. O2 participates in several (enzymatic) reactions, including those resulting in the oxidation of free sulfhydryl groups, thereby increasing dough strength and bread volume. We here incorporated different O2 levels in dough by mixing dough samples for a fixed time under different modified atmospheres which led to significant changes in dough free sulfhydryl contents and bread volumes. Although altering the mixing time not only impacted how much O2 was incorporated in dough but also the mechanical input, the changes in dough and bread properties when using different mixing times, largely depended on differences in O2 uptake. When used in bread recipes, redox agents such as azodicarbonamide (ADA) and ascorbic acid (AH2) impact the dough sulfhydryl contents and bread volumes. The effect of different levels of O2 incorporation on dough samples which contained ADA or AH2 was studied by altering the mixing time or the O2 content in the mixing atmosphere. Lower ADA levels were needed when dough was mixed under an atmosphere enriched in O2. As AH2 requires O2 to be converted to dehydroascorbic acid (DHA) to exert its improver effect, it came as a surprise that when it was included in a dough which was prepared under O2 enriched conditions, no additional impact was obtained and that, even under reduced O2 conditions, its use still resulted in an increased bread volume. These findings suggest that AH2 oxidase very effectively uses O2 to form DHA.

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.

Intact and Damaged Wheat Starch and Amylase Functionality During Multilayered Fermented Pastry Making.

The roles of native and damaged starch (DS) during fermented pastry making were examined by increasing the level of DS in wheat flour by ball-milling and/or by including amylase in the recipe. Increased DS levels increase laminated dough strength presumably by making less water available for the gluten. This effect was partly overcome by amylase use. During baking, a reduced resistance of the dough to gas cell expansion, as a result of enzymatic starch hydrolysis, seems responsible for increased pastry lift and improved crumb structure. Gelatinization of intact starch limits dough lift and expansion. Even at high amylase dosages structural collapse was limited, which suggests a significant role for gluten in pastry product structure formation. Differential scanning calorimetry and low-resolution 1 H nuclear magnetic resonance experiments indicated that increased levels of starch damage and amylase use impact the amylose network in the product and respectively increase and decrease the extent to which amylopectin retrogrades during storage. PRACTICAL APPLICATION: This research article evaluates the role of intact and damaged wheat starch during the production of fermented pastry products. An expanded knowledge on starch functionality during the different pastry production steps allows for a targeted selection of additives to improve product quality and production efficiency. The results obtained in this study can contribute to the realization of industrially feasible solutions for the production of quality pastry products.

The impact of disulfide bond dynamics in wheat gluten protein on the development of fermented pastry crumb.

Gluten proteins functionality during pastry production was examined by including redox agents in the ingredient bill. Addition of reducing and oxidizing agents respectively increased and decreased dough height during fermentation. The presence of large gas bubbles in the samples with oxidizing agents may have caused a 'stacking'-effect and a more effective dough lift. During baking, the level of extractable proteins decreased to comparable values for all samples, except when potassium iodate (KIO3) was used in the recipe. As a result of its use, a lower level of gliadin was incorporated into the gluten polymer and dough layers tended to 'slide' apart during baking, thereby causing collapse. Most likely, KIO3 caused glutenin oxidation within each individual dough layer to such extent during the dough stage that insufficient thiol groups were available for forming dough layer interconnections during baking, after margarine melting. Furthermore, addition of redox agents impacted the product's crumb structure.

Storage of parbaked bread affects shelf life of fully baked end product: a ¹H NMR study.

Full baking of earlier partially baked (parbaked) bread can supply fresh bread to the consumer at any time of the day. When parbaked bread loaves were stored at -25, 4 or 23°C, the extent of crumb to crust moisture migration and amylopectin retrogradation differed with storage temperature, and the firming rate was evidently lowest during frozen storage. The extent of crumb to crust moisture migration during parbaked bread storage largely determined the mass of the fresh finished bread, and its crumb and crust moisture contents. Initial NMR proton mobility, initial resilience, the extent of amylopectin retrogradation and changes in firmness and resilience during storage of fully baked bread were affected by its crumb moisture content. The lowest firming rate was observed for finished bread resulting from parbaked bread stored at -25°C, while the highest firming rate was observed for finished bread from parbaked bread stored at 23°C.

Biopolymer interactions, water dynamics, and bread crumb firming.

To establish the relationship between biopolymer interactions, water dynamics, and crumb texture evolution in time, proton mobilities in starch and gluten model systems and bread were investigated with NMR relaxometry. Amylopectin recrystallization was observed as an increased amount of fast-relaxing protons, while network strengthening and changes in water levels were noted as a reduced mobility and amount, respectively, of slowly relaxing protons. Amylopectin recrystallization strengthened the starch network with concomitant inclusion of water and increased crumb firmness, especially at the beginning of storage. The inclusion of water and the thermodynamic immiscibility of starch and gluten resulted in local gluten dehydration during bread storage. Moisture migration from crumb to crust further reduced the level of plasticizing water of the biopolymer networks and contributed to crumb firmness at longer storage times. Finally, we noted a negative relationship between the mobility of slowly relaxing protons of crumb polymers and crumb firmness.