The impact of diurnal photosynthetic activity on the fine structure of the amylopectin fraction of starch synthesized by normal barley (NBS) and waxy barley (WBS), the latter completely devoid of amylose biosynthesis, was determined following the cultivation under normal diurnal or constant light growing conditions. The amylopectin fine structures were analysed by characterizing its unit chain length profiles after enzymatic debranching as well as its φ,β-limit dextrins and its clusters and building blocks after their partial and complete hydrolysis with α-amylase from Bacillus amyloliquefaciens, respectively. Regardless of lighting conditions, no structural effects were found when comparing both the amylopectin side-chain distribution and the internal chain fragments of these amylopectins. However, the diurnally grown NBS and WBS both showed larger amylopectin clusters and these had lower branching density and longer average chain lengths than clusters derived from plants grown under constant light conditions. Amylopectin clusters from diurnally grown plants also consisted of a greater number of building blocks, and shorter inter-block chain lengths compared to clusters derived from plants grown under constant light. Our data demonstrate that the diurnal light regime influences the fine structure of the amylopectin component both in amylose and non-amylose starch granules.

This study investigated the influence of diurnal photosynthetic activity on the morphology, molecular composition, crystallinity, and gelatinization properties of normal barley starch (NBS) and waxy barley starch (WBS) granules from plants cultivated in a greenhouse under normal diurnal (16 h light) or constant light photosynthetic conditions. Growth rings were observed in all starch samples regardless of lighting conditions. The size distribution of whole and debranched WBS analyzed by gel-permeation chromatography did not appear to be influenced by the different lighting regimes, however, a greater relative crystallinity measured by wide-angle X-ray scattering and greater crystalline quality as judged by differential scanning calorimetry was observed under the diurnal lighting regime. NBS cultivated under the diurnal photosynthetic lighting regime displayed lower amylose content (18.7%), and shorter amylose chains than its counterpart grown under constant light. Although the relative crystallinity of NBS was not influenced by lighting conditions, lower onset, peak, and completion gelatinization temperatures were observed in diurnally grown NBS compared to constant light conditions. It is concluded that normal barley starch is less influenced by the diurnal photosynthetic lighting regime than amylose-free barley starch suggesting a role of amylose to prevent structural disorder and increase starch granule robustness against environmental cues.

Starch granules derived from certain tuber or root crops exhibit a B‐type polymorphic pattern and amylopectin with a high content of long B‐chains and comparatively long segments between the building blocks. Here, four B‐crystalline starches are selected to study their morphology and molecular composition, including lintnerization conducted at two different temperatures. The structure of the granules suggests that the B‐type crystalline starches can be divided into two distinct groups, with potato and edible canna forming one group having large granules with typical “growth rings” and the molecular structure of the lintners being dependent on the temperature of lintnerization. The other group consists of shoti and lesser yam starches possessing granules with alternating “granular slices” instead of rings or shells and the molecular composition of the lintners is not dependent on the temperature. It is found that the former group of starch possess lower gelatinization temperatures and swell at lower temperatures than the latter group, suggesting a more labile granular structure of potato and canna starches compared to shoti and lesser yam. As the properties are not related to the amylose or phosphate content of the granules, the result suggests that B‐crystalline starch granules are found as at least two distinct structural types with unique architectures.

The effects of amylose deposition on crystalline regions of barley starch granules were studied in granules containing zero to 99.1% amylose using “waxy” (WBS, 0% amylose), normal (NBS, 18% amylose) and amylose-only barley lines (AOS, 99.1% amylose). The effects were probed after hydrolysis of amorphous regions of starch granules in dilute HCl generating lintners, which typically represent the crystalline lamella of starch granules. Compared to NBS and WBS, AOS granules exhibited an irregular, multilobular morphology with a rough surface texture. AOS displayed lower rates of acid hydrolysis than WBS, and AOS reached a plateau at ∼45wt% acid hydrolysis. High-performance anion-exchange chromatography of lintners at equivalent levels of hydrolysis (45wt%) revealed the average degree of polymerization (DP) of AOS lintners was 21, substantially smaller than that of NBS and WBS (DP 42). AOS lintners contained the lowest number of chains (NC) per molecule (1.1) compared to NBS (2.8) and WBS (3.3) and the average chain length of AOS, NBS and WBS lintners was 19, 15 and 13, respectively. Hence, both NC and the average chain length correlated with amylose content. The size distribution profile of AOS lintners revealed a repeat motif in the molecules corresponding to 5–6 glucose residues.

Two product matrices with different concentrations of grains will be discussed that are representative of a wide variety of grain-based baked products. Product staling is a complicated phenomenon due to the vast number of interactions taking place among and between starch, proteins, lipids, and water. Aspects of staling relating to baked products will be discussed including mechanisms of staling, methodologies for determining attributes of staling, and anti-staling strategies.

Structured emulsions, including monoacylglycerol (MAG) gels, are of interest as alternatives to shortenings rich in saturated and trans fatty acids (SFA and TFA). However, an understanding of their physical and nutritional functionality in baked products is limited. The objective of this randomized crossover study was to compare the postprandial lipid and glucose responses to two different baked product matrices produced with a MAG gel. Differences between study treatments are discussed in the context of underlying ingredient interactions impacting, primarily, starch digestibility. Healthy males (n = 18, 19-40 years, BMI ≤27 kg m(-2), waist circumference ≤102 cm, fasting plasma glucose <5.6 mmoL L(-1), insulin <180 pmol L(-1) and TAG <1.7 mmol L(-1)) attended six study visits, each separated by at least one week, and consumed one of six study treatments with subsequent blood sampling for 6 h for determination of triacylglycerol (TAG), glucose, insulin and free fatty acids (FFA). The study treatments consisted of sugar-free cakes and cookies (high and low moisture products, respectively) produced using either the canola oil-based structured MAG gel or the compositionally-equivalent MAG gel ingredients. Although MAG gel structure per se did not impact postprandial response, all cookies had higher TAG responses compared with cakes, even when matched for fat content. Sugar cookies containing 40 g of the MAG gel or an industry standard stearic-rich shortening were also compared, with no differences observed in postprandial response.

In this study we report on the effects of structuring, aging, temperature, and shear history on the polymorphism and stability of structured monoglyceride stabilized oil in water emulsions, or MAG gels. With knowledge that the structure of the gel is paramount towards its functionality, this study investigated how structuring of MAG gel affects proton relaxation and monoglyceride crystal polymorphism. The structured MAG gel was compared to its compositionally equivalent unstructured components containing either dry or hydrated monoglycerides. Proton relaxation studies were conducted using pulsed proton Nuclear Magnetic Resonance T 2 relaxation analysis. Powder X-ray Diffraction was used to determine the monoglyceride crystal polymorphism within the system. Proton relaxation was greatly affected by the structuring of MAG gel components, with the structured MAG gel displaying faster relaxation times compared to its unstructured components. The structured MAG gel also displayed different polymorphic behaviour than its unstructured components, with structured gels exhibiting greater stability, and displaying both α and β monoglyceride polymorphic forms. The application of shear resulted in greater water mobility within MAG gels compared to non-sheared samples, as well as a greater proportion of the β polymorphic population. This study established a relationship between water mobility determined by T 2 relaxation analysis and the proportion of the β polymorph population determined through XRD reflections. It clearly demonstrates that an increase in the β polymorph population leads to a decrease in the strength of water binding, and that shear enhances this process.

This paper investigates the use of a novel monoglyceride stabilized oil in water emulsion as a shortening alternative in cookies. We report on the effects of the monoglyceride stabilized emulsion on cookie quality attributes when compared to formulations containing all purpose shortening. Furthermore, the role of structuring and its effects on the monoglyceride stabilized emulsion functionality in cookies were determined by comparing quality attributes of cookies containing the structured emulsion to those containing the unstructured components of the monoglyceride emulsion. Cookie quality attributes measured included dough firmness, cookie break strength, cookie spread, surface colour, and textural shelf life analysis. Water mobility of cookie dough was also determined using proton Nuclear Magnetic Resonance analysis. It was determined that the structured monoglyceride emulsion resulted in greater dough firmness, and decreased width and length values than doughs containing its unstructured components. However, cookies with all purpose shortening displayed superior quality attributes, as expected.

ABSTRACTStarch is a major part of our diet. Food processing determines the physicochemical properties of starch in processed foods. An understanding of such properties is important in the development of strategies to modulate desirable textural attributes as well as the digestibility of starch in foods such as baked and extruded products. This review summarises the molecular interactions that occur during gelatinization and retrogradation of starch molecules studied using starch‐water systems focusing on those with starch concentrations of 60–150% db relevant to baked and extruded foods. Little information exists on effects of starch concentration on digestibility and polymer conformations and structures of processed starch in concentrated systems.

Summary In this study, we report on the effects of cellulose fibres of different particle size on changes to dough water absorption and rheology; and on effects of fibre on starch and gluten, separately, at different levels of fibre incorporation (0.1–10%). Water absorption and dough‐mixing properties were affected with fibre incorporation, with 40‐μm fibre incorporation resulting in greater absorption values. Dough stickiness and extensibility were affected by cellulose fibre particle size, and decreased with increasing fibre addition. Flour or starch and fibre mixtures were evaluated using a Micro ViscoAmlyoGraph (MVAG), and the resulting gel firmness was measured using a texture analyzer. MVAG peak and final viscosities of flour samples decreased with increasing fibre content. Starch–fibre interactions followed a similar trend as flour–fibre treatments. Gluten–fibre interactions were also measured using a Gluten Peak Tester on flour–fibre and gluten–fibre mixtures. Cellulose fibre enhanced the kinetics of gluten aggregation.