High-amylose resistant starch breads were long-stored (11 days) at 20 °C for kinetic analysis of different aspects of the staling process. Bread products were formulated on a French-bread recipe ...basis and replacing wheat flour by type II resistant starch at different levels: 0% (control), 10% (HM10), 20% (HM20) and 30% (HM30). Experiments included measurements of water activity, moisture loss, amylopectin retrogradation by DSC, crystallinity changes by X-ray diffraction, and firmness by texture analysis. In the presence of resistant starch water loss was slower, allowing amylopectin retrogradation to be more extensive. However, HM10 and HM20 had similar firming behavior to the control, likely due to the similar and adequate quality that these breads showed initially (at day 0). In contrast, samples with high resistant starch content such as HM30 presented a poor-quality and highly filled crumb that led to the highest firmness during storage.
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•Presence of type II resistant starch in wheat breads slowed down crumb water loss.•Amylopectin retrogradation was more extensive in the presence of resistant starch.•Breads formulated with 0%, 10% and 20% resistant starch had similar firming behavior.•Initial mechanical characteristics of bread crumb influenced the stiffening process.•Breads with 30% resistant starch showed the highest hardness at the end of storage.
•X-ray diffraction was used to analyse starch crystallinity of bread during storage.•Resistant starch (RS) content had the same pattern of increase as crystallinity.•RS formation was greater for ...refrigeration than ambient or frozen temperatures.•A strong statistical relationship between crystallinity with XRD and RS content was obtained.
Resistant starch (RS) can form during storage of foods, thereby bestowing a variety of potential health benefits. The purpose of the current study has been to determine the influence of storage temperature and time on the crystallinity and RS content of bread. Loaves of white bread were baked and stored at refrigeration, frozen and room temperatures with analysis over a period of zero to seven days. RS determination and X-ray diffraction (XRD) were used to evaluate the influence of storage temperature and time on total crystallinity and RS content. The rate of starch recrystallisation was affected by storage temperature and time, where refrigeration temperatures accelerated RS formation and total crystallinity more than storage time at both frozen and room temperature. A strong statistical model has been established between RS formation in bread and XRD patterns, having a 96.7% fit indicating the potential of XRD to measure RS concentrations.
In this study, lignin was synthesized from the waste leaves of Ficus auriculata obtained after the extraction of gallic acid. The synthesized lignin was incorporated into PVA films, and the neat and ...blended films were characterized using different techniques. Lignin addition improved the UV-shielding, thermal, antioxidant, and mechanical properties of PVA films. The water solubility decreased from 31.86 % to 7.14 ± 1.94 %, while the water vapor permeability increased from 3.85 ± 0.21 × 10−7 g.m.h−1 Pa−1 to 7.84 ± 0.64 × 10−7 g.m.h−1 Pa−1 for pure PVA film and the film containing 5 % lignin, respectively. The prepared films showed a much better performance than commercial packaging films in inhibiting mold growth during the storage of preservative-free bread. The bread samples packed with commercial packaging showed signs of mold growth on the 3rd day, while the growth was inhibited entirely till the 15th day for PVA film containing 1 % lignin. The pure PVA film and the ones containing 3 % and 5 % of lignin inhibited growth till the 12th and 9th day, respectively. Findings from the current study show that safe, cheap, and eco–friendly biomaterials can hinder the growth of spoilage microorganisms and potentially be used in food packaging.
•Lignin synthesis from spent leaves of Ficus auriculata•Incorporation of lignin into PVA film for food packaging•Enhancement of functional properties of PVA film after lignin incorporation•Excellent performance of prepared films in mold inhibition during bread storage
The physicochemical stability of six bread formulations with different tilapia flour (BTF) levels (0%, 2.5%, 5%, 10%, 15%, and 20%) in substitution to wheat flour was investigated regarding moisture ...content, water activity (a
w
), pH, instrumental color parameters, texture profile, lipid and protein oxidation on days 0, 2, 4, 6 and 8 at 25°C. BTF10%, BTF15%, and BTF20% displayed lower (P < 0.05) moisture, aw, lightness index, cohesiveness, springiness and resilience, and higher (P < 0.05) pH, redness index, yellowness index, hardness, chewiness, lipid and protein oxidation compared to BTF0%, BTF2.5%, and BTF5%. Nevertheless, pH drops, lipid and protein oxidation were less pronounced (P < 0.05) for BTF10%, BTF15%, and BTF20% during storage. Although quality loss has been observed in breads containing ≥ 10% TF, bread at 5% TF did not display altered traditional wheat bread physicochemical characteristics and may be an attractive alternative for the health food market.
During storage of frozen par-baked breads for a prolonged period of time, bread quality may undergo changes such as increased firmness, moisture and flavour losses resulting in product deterioration. ...Four categories of par-baked breads namely—variety, white, multi-grain and rye were stored at −18°C for 9 months to evaluate the effects of storage period on product quality, and to develop prediction models that describe kinetics of deterioration of selected quality parameters. The quality was evaluated based on sensory, chemical and physical attributes and properties. Storage life was determined based on the changes in bread quality below certain level. The principal component analysis indicated that approximately 90% of the total variability of 19 quality parameters can be explained with only two principal components. The zero-order kinetic reaction showed good agreement (
R
2>80%) with quality changes observed by the sensory panel over the storage period. A prediction model, based on the bread quality at zero time and the quality at the time when the bread was rejected by the sensory panel, was developed. The proposed prediction model would provide a useful means of estimating storage life of par-baked breads made with similar formulations.
Abstract A soy bread of fully acceptable quality and containing 49% soy ingredients (with or without 5% almond powder) has been recently developed in our laboratory. An investigation on water ...distribution and mobility, as probed by proton signal intensity and T2 magnetic resonance images, during storage was designed to examine possible relations between water states and hindered staling rate upon soy or soy–almond addition. Water proton distribution throughout soy-containing loaves was found to be very homogeneous in fresh breads with and without almond, with minimal water migration occurring during prolonged storage. In contrast, traditional wheat bread displayed an inhomogeneous water proton population that tended to change (with higher moisture migration towards the outer perimeter of the slice) during storage. Similar results were found for water mobility throughout the loaves, as depicted in T2 images. On intensity images of all considered bread varieties, the outer perimeter corresponding to the crust exhibited lower signal intensity due to decreased water content. Higher T2 values were found in the crust of soy breads with and without almond, which were attributed to lipids. The results indicated that the addition of soy to bread improved the homogeneous distribution of water molecules, which may hinder the staling rate of soy-containing breads. However, incorporation of almond had little effect on the water proton distribution or mobility of soy breads.
Effects of packing in modified atmosphere (MA, 30% CO2 and 70% N2) and storage in freezer and room temperature on the shelf-life of a hot-dog type bakery product were determined based on changes in ...both the content of resistant starch (RS) (quantified by enzymatic and calorimetric methods) and crumb texture during 15 week storage. Irrespective of storage conditions the humidity of the crumb continued to decrease with time from 34.80% to 31-32%, however this decrease was lesser when the bakery product was kept frozen. Storage conditions strongly affected both RS formation and crumb firmness. The highest increase in RS content was observed when the bakery product was packed in normal atmosphere and kept in a freezer while the crumb firmness was the lowest when it was packed in MA and kept at room temperature (2.67 N MAP-room, 13.02 N MAP frozen, 17.42 N frozen). A type of RS polymorph formed during the storage depended on storage conditions. It was proved by different temperatures of RS melting and different characters of peaks in endothermal DSC curves. MA was found to prevent changes in the crumb texture and slow down starch restructuring only when the hot-dog type bakery product was kept at room temperature. Freezing and freezer storage extended its shelf-life but did not stop worsening of its quality.
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