Physical properties and water state changes during storage in soy bread with and without almond

Changes in the starch quality of adlay seed varieties (Coix lacryma-jobi L.) from different regions in China after high-temperature storage

The effects of high-temperature storage at 37 °C on the crystallinity, pasting, rheological, and thermal properties of adlay seed starches from three famous Chinese varieties were studied. The results showed that high-temperature storage altered the natural structure of adlay seed starch, resulting in increased peak viscosity for all starch pastes after one month of storage at 37 °C. Jinsha adlay seed starch (JSC), which had the highest amylose content (11.21 %), showed increased D50, relative crystallinity and OD values, demonstrating strong regrowth ability and hydrophobicity, with starch gels having greater hardness and gumminess after storage. In contrast, Pucheng adlay seed starch (PSC) and waxy Ninghua adlay seed starch (WSC), with similar amylose proportions, showed distinct starch gel properties. PSC (with an amylose content of 3.35 %) exhibited better starch gel properties, whereas WSC (amylose content of 5.74 %) demonstrated improved gumminess and chewiness after storage and exhibited stronger anti-starch regrowth capabilities. This study provides valuable insights into the selection of future starches based on their specific processing requirements.

Effect of synergistic fermentation of Lactobacillus plantarum and Saccharomyces cerevisiae on thermal properties of wheat bran dietary fiber-wheat starch system

A synergistic fermentation system was constructed using single strains of Lactobacillus plantarum and Saccharomyces cerevisiae cultured separately; wheat starches containing different wheat bran dietary fiber (WBDF) levels (0, 3, 6, 9 & 12%) were fermented in this system. The thermal properties of materials were measured by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and rapid viscosity analysis (RVA). The results showed that WBDF may alter the thermal behavior of starch by forming hydrogen bonds with the leached starch chains and limit the available water of starch. The viscosity properties (peak, trough, and final viscosity) and setback decreased, and they were negatively correlated with the WBDF levels. In addition, dynamic rheological measurements showed that the addition of WBDF significantly enhanced the elasticity of fermented starch gels while slightly improving the mechanical strength, and 6% level of WBDF had the largest contribution. This study provides some data for the production of high dietary fiber fermented flour products, both common and gluten-free.

Effect of Frying and Roasting Processes on the Oxidative Stability of Sunflower Seeds (Helianthus annuus) under Normal and Accelerated Storage Conditions

The effect of different cooking processes such as frying and roasting on the oxidative stability of sunflower seeds was evaluated under accelerated oxidation and normal storage conditions. The fatty acid composition by GC-MS showed a higher amount of linoleic acid in fried samples due to the replacement of the seed moisture by the frying oil. On the other hand, roasted samples presented a higher oleic acid content. DSC and TGA results showed some decrease in the thermal stability of sunflower seed samples, whereas PV and AV showed the formation of primary and secondary products, with increasing oxidation time. Roasted sunflower seeds showed seven main volatile compounds characteristic of the roasting process by HS-SPME-GC-MS: 2-pentylfuran, 2,3-dimethyl-pyrazine, methyl-pyrazine, 2-octanone, 2-ethyl-6-methylpyrazine, trimethyl-pyrazine, and trans,cis-2,4-decadienal, whereas fried samples showed six volatile characteristic compounds of the frying process: butanal, 2-methyl-butanal, 3-methyl-butanal, heptanal, 1-hexanol, and trans,trans-2,4-decadienal. The generation of hydroperoxides, their degradation, and the formation of secondary oxidation products were also investigated by ATR-FTIR analysis. The proposed methodologies in this work could be suitable for monitoring the quality and shelf-life of commercial processed sunflower seeds with storage time.

Deterioration mechanisms of high-moisture wheat-based food - A review from physicochemical, structural, and molecular perspectives

Wheat-based products are staple foods for over a third of the world's population. However, most wheat-based staple foods are provided with a high water content to maintain naturally chewable mouthfeel, which leads to a short shelf life and limits their distribution and marketing. Understanding the fundamental mechanisms and dynamics that drive the quality deterioration is therefore essential for obtaining alternative technologies for optimal quality and extended shelf life. Here, we provide the basis for the physicochemical, structural, and molecular changes occurring in various wheat products during storage, intending to elucidate the underlying deterioration causes. Generally, more desirable qualities are obtained for fresh wheat products, both in appearance and mouthfeel. During storage, changes in the physicochemical properties, structure, main constituents, and water status contribute to the quality deterioration. Based on these changes, deterioration mechanisms are summarized to provide both theoretical and practical references for the quality regulation of high-moisture wheat-based food.

A facile method to synthesize strong salt-enhanced hydrogels based on reversible physical interaction

To overcome the adverse effects of salt on the mechanical properties of hydrogels, a facile double cross-linking method has been proposed to synthesize salt-enhanced tough hydrogels. Herein, a poly(hexafluorobutyl methacrylate-acrylamide) hydrogel [P(AAm-co-HFBMA) hydrogel] is prepared by the copolymerization of acrylamide (AAm) and hexafluorobutyl methacrylate (HFBMA) with N,N'-methylene bisacrylamide (NMBA) as a cross-linking agent in a dimethylformamide (DMF)/aqueous solution; DMF is then replaced by water. The results indicate that the tensile fracture stress of the P(AAm-co-HFBMA) hydrogel (20 mol% HFBMA) is as high as 0.43 MPa, which is far better than that of the PAAm hydrogel (ca. 30 kPa). Additionally, with a further increase in the hydrophobic structural units (25 mol% HFBMA), the tensile fracture stress of the P(AAm-co-HFBMA) hydrogel can be increased up to 2.34 MPa. The mechanical strength of the P(AAm-co-HFBMA) hydrogel is significantly enhanced to 3.50 MPa (2 M) from 2.34 MPa (0 M) after it is soaked in aqueous NaCl solutions with various salt concentrations. The mechanical properties and the results of the DSC analysis indicate that the main reason for its mechanical strength to exhibit a unique salt-enhancement trend can be explained as follows. After the P(AAm-co-HFBMA) hydrogel is soaked in the salt solution, the network gradually collapses with the penetration of the small molecules of salt. Thus, the hydrophobic C-F units easily form dynamic cross-linking junctions due to the switchable hydrophobic interaction between C-F groups, which can endow the P(AAm-co-HFBMA) hydrogel with a more effective dynamic energy dissipation mechanism in salt solution.

Physicochemical properties, structural transformation, and relaxation time in strength analysis for honey powder models

Present study developed a strength analysis for relaxation time (τ) in characterizing physicochemical properties and structural transformation of freeze-dried honey/whey protein isolate (H/WPI) and honey/maltodextrin (H/MD) models based on water sorption, time-dependent crystallization, glass transition, and α-relaxation at various water activities (0.11a_w to 0.76a_w) and 25 °C. Water sorption data of two models explained WPI was a more effectiveness drying stabilizer than MD as H/WPI model owned higher monolayer water content. Crystallization was observed in prepared models with drying-aids content below 50% of mass ratios at water activity above 0.44a_w and 25 °C, whereas the extent of crystallization and structural collapse were inhibited by WPI and MD addition based on sorption isotherms. Glass transition temperature, α-relaxation temperature, and τ for two models were composition-dependent and altered by water, WPI, and MD at water activity below 0.44a_w. According to strength analysis of τ, the S for H/WPI and H/MD models was affected by drying-aids and could give a quantitative measure to estimate compositional effects on τ. Moreover, a S-involved state diagram was established to determine the critical parameters (water content and S) for controlling structural transformation of honey powder models during production and storage, i.e., collapse and stickiness.

Nutritional Profile and Chemical Stability of Pasta Fortified with Tilapia (Oreochromis niloticus) Flour

Physicochemical parameters of pasta enriched with tilapia (Oreochromis niloticus) flour were investigated. Five formulations were prepared with different concentrations of tilapia flour as partial substitute of wheat flour: pasta without tilapia flour (PTF0%), pasta with 6% (PTF6%), 12% (PTF12%), 17% (PTF17%), and 23% (PTF23%) of tilapia flour. The formulations were assessed for proximate composition, fatty acid and amino acid profile on day 1 whereas, instrumental color parameters (L*, a* and b* values), pH, water activity (aw), and lipid and protein oxidation were evaluated on days 1, 7, 14, and 21 of storage at 25°C. Fortification with tilapia flour increased (p < 0.05) protein, lipid, ash, total essential amino acids, and total polyunsaturated fatty acids contents. In addition, supplementation of pasta with tilapia flour decreased (p < 0.05) lightness and water activity while redness, yellowness, pH values, and lipid oxidation were increased (p < 0.05) in a level-dependent manner. Nevertheless, all formulations were exhibited storage stability at 25°C. In general, protein oxidation was greater (p < 0.05) in the pasta containing 12%, 17%, and 23% of tilapia flour than their counterparts, and the storage promoted an increase (p < 0.05) on the carbonyl content in all formulations. Thus, pasta with 6% of tilapia flour has the potential to be a technological alternative to food industry for the nutritional enrichment of traditional pasta with negligible negative effects on the chemical stability of the final product during 21 days at 25°C.

A green tea-containing starch confection increases plasma catechins without protecting against postprandial impairments in vascular function in normoglycemic adults

Postprandial hyperglycemia (PPH) increases cardiovascular disease risk regardless of glucose intolerance by transiently impairing vascular endothelial function (VEF) by limiting nitric oxide bioavailability in an oxidative stress-dependent manner. Preclinical studies show that green tea catechins attenuate PPH by inhibiting starch digestion. We hypothesized that a starch-based confection containing catechin-rich green tea extract (GTE) would limit PPH-mediated impairments in VEF in normoglycemic adults. We formulated a unique GTE confection and then conducted a double-blind, randomized, controlled, crossover study in healthy men (n = 15; 25.3 ± 1.0 years; 22.4 ± 1.8 kg m(-2)) in which they ingested starch confections (50 g carbohydrate) formulated with or without GTE (1 g) prior to evaluating sensory characteristics of confections and plasma glucose, biomarkers of lipid peroxidation and nitric oxide homeostasis, and brachial artery flow-mediated dilation (FMD) at 30 min intervals for 3 h. Sensory evaluation of confections indicated acceptable consumer appeal and an inability to distinguish between confections regardless of GTE. Plasma catechins concentrations increased following ingestion of the GTE confection. However, plasma glucose peaked at 60 min (P < 0.05) following confection ingestion and was unaffected throughout the postprandial period by the GTE confection (P > 0.05). FMD was significantly decreased only at 60 min regardless of confections containing GTE. Also at 60 min, both confections similarly increased plasma malondialdehyde while decreasing arginine and increasing asymmetric dimethylarginine/arginine. The successfully formulated GTE-containing confection effectively delivered catechins, but without mitigating PPH-mediated impairments in VEF in association with oxidative stress that likely limits nitric oxide bioavailability.

Bread Staling: Updating the View

Staling of bread is cause of significant product waste in the world. We reviewed the literature of the last 10 y with the aim to give an up-to-date overview on processing/storage parameters, antistaling ingredients, sourdough technology, and measurement methods of the staling phenomenon. Many researchers have been focusing their interest on the selection of ingredients able to retard staling, mainly hydrocolloids, waxy wheat flours (WWF), and enzymes, but different efforts have been made to understand the molecular basis of bread staling with the help of various measurement methods. Results obtained confirm the central role of amylopectin retrogradation and water redistribution within the different polymers in determining bread staling, but highlighted also the importance of other flour constituents, such as proteins and nonstarch polysaccharides. Data obtained with thermal, spectroscopy, nuclear magnetic resonance, X-ray crystallography, and colorimetry analysis have pointed out the need to encourage the use of one or more of these techniques in order to better understand the mechanisms of staling. Results so far obtained have provided new insight on bread staling, but the phenomenon has not been fully elucidated so far.

Type and amount of lipids influence the molecular and textural properties of a soy soft pretzel

Altering baked goods by the addition of nutrient-rich ingredients, such as soy and ground almonds, affects the water and lipid distribution of the product and, subsequently, its final quality. Here, we studied how three lipid sources, shortening, canola oil, and ground almonds, affected texture and water distribution in a baked soy pretzel and the molecular mobility in the dough. Pretzel crumb from all formulations exhibited 40-43% moisture with a little more than half present as "freezable" water. Firmness and chewiness decreased with increased shortening and canola oil, whereas firmness and chewiness increased with additional almonds. In contrast, neither springiness nor cohesiveness was affected by the lipid quantity or source. Finally, magnetic resonance imaging of the soy pretzel dough revealed two or three populations of dough components that have distinct molecular mobilities. With increased lipid content, the mobility of each population increased in magnitude and heterogeneity. Interestingly, almonds had the smallest effect on the molecular mobility of the dough but had the largest effect on textural properties. These results provide quantitative insight into the mechanisms by which the lipid source can influence molecular properties that have textural implications for bakery products.

Physicochemical characterization and sensory analysis of yeast-leavened and sourdough soy breads

Sourdough fermentation has been shown to have numerous beneficial effects on bread quality, and nutritionally enhance soy-supplemented bread by altering isoflavone chemical forms. Given this, the objective of this study was to compare the loaf quality and shelf life of sourdough and yeast-leavened soy breads by various physical, thermal, and sensorial methods, and to assess the effects of fermentation by various microorganisms on isoflavone profile in dough and breads using high-performance liquid chromatography analysis. Sourdough fermentation yielded a less extensible dough compared to yeast-leavened soy dough (P < 0.001), and resulted in a harder bread crumb (P < 0.05) and lighter crust color (P < 0.001), compared to yeast-leavened soy bread (Y-B). Sensory analysis revealed a significantly higher overall liking of Y-B compared to sourdough soy bread (SD-B) (P < 0.001). Segmentation analysis of the cohort suggests that overall liking and bread consumption frequency may be determinants of Y-B or SD-B preference. SD-B and Y-B exhibited similar shelf-life properties. Despite significantly different enthalpies associated with the melting of amylose-lipid complexes, thermal analysis of the 2 soy breads stored for 10 d (ambient conditions) demonstrated no significant difference in water distribution and starch retrogradation (P < 0.05). Lastly, SD-B was determined to have 32% of total isoflavones occurring in the aglycone form compared to 17% in Y-B. These findings warrant further investigation of sourdough fermentation as a processing technique for quality and nutritional enhancement of soy-based baked goods.

Physicochemical properties and consumer acceptance of wheat-germinated brown rice bread during storage time

Selected physicochemical properties and consumer acceptance of bread prepared from composite flour (wheat:germinated brown rice:germinated glutinous brown rice flours at 60:30:10 ratio) were evaluated during storage for 0, 3, and 5 d, and compared with wheat bread (0 d, control). During storage, color profiles and water activity (from 0.947 to 0.932) of crumbs of composite flour breads slightly changed, but moisture content drastically decreased along with increasing crumb hardness (from 4.16 N to 10.37 N). Higher retrogradation in bread crumb was observed particularly for 5-d stored bread (DeltaH = 2.24 J/g) compared to that of the fresh composite bread and the control (DeltaH = 0.70 and 0.51 J/g, respectively). Mean (n = 116) overall liking score of the fresh composite flour bread (0 d) was slightly lower than that of the control (7.1 compared with 7.6 based on a 9-point hedonic scale). At least 76% of consumers would purchase the fresh composite flour bread if commercially available. Breads were differentiated by textural (moistness, smoothness, and softness) acceptability with canonical correlation of 0.84 to 0.87. The signal-to-noise ratio values of the 5-d stored breads were lower than the control, due mainly to the non-JAR (not-enough) intensity responses for moistness, smoothness, and softness; the mean drop of liking scores for these attributes ranged from 2.42 to 2.98. Flavor acceptability and overall liking were factors influencing consumers' purchase intent of composite flour breads based on logistic regression analysis. This study demonstrated feasibility of incorporating up to 40% germinated brown rice flour in a wheat bread formulation. Practical Application: Our previous study revealed that flours from germinated brown rice have better nutritional properties, particularly gamma-aminobutyric acid (GABA), than the nongerminated one. This study demonstrated feasibility of incorporating up to 40% germinated brown rice flour in a wheat bread formulation. In the current U.S. market, this type of bread may be sold as frozen bread that would have a longer shelf life, or may be supplied as a food-service product that would be made-to-order or made fresh daily as currently practiced in some major grocery stores.