The Role of Hydrocolloids in Gluten-Free Bread and Pasta; Rheology, Characteristics, Staling and Glycemic Index

Hydrocolloids are important ingredients controlling the quality characteristics of the final bakery products. Hydrocolloids are frequently used in gluten-free (GF) recipes, mimicking some rheological properties of gluten, improving dough properties, delaying starch retrogradation and improving bread texture, appearance and stability. Hydrocolloids addition increases viscosity and incorporation of air into the GF dough/batter. Besides their advantages for the technological properties of the GF bread, hydrocolloids addition may impact the glycemic index (GI) of the final product, thus answering the demand of people requiring products with low GI. This review deals with the application of hydrocolloids in GF bread and pasta with a focus on their effect on dough rheology, bread hardness, specific volume, staling and GI.

PSIV-9 Effective ruminal degradability of steam-flaked corn is influenced by flake density and starch retrogradation

The objective of this study was to evaluate in situ ruminal digestion characteristics of steam-flaked corn with large differences in starch availability (SA) using two different models: 1) increasing flake density and 2) exposure to 55°C temperatures to induce starch retrogradation. Five ruminally-cannulated steers (body weight = 390 ± 7.86 kg) were pen-fed a starter diet. In Exp. 1, sifted flakes with flake densities of 257, 296, 335, 373, and 412 g/L (SA: 87%, 76%, 66%, 43%, and 49%, respectively) were evaluated. In Exp. 2, three steam-flaked corn fractions were evaluated: flakes + fines (not sifted), sifted flakes (>4-mm), and sifted fines (< 4-mm). Feed fractions were stored for 3-d at either 23°C or 55°C (average SA across steam-flaked corn fractions: 53.3% and 25.5% respectively). Treatments of Exp. 2 were arranged with a 3 × 2 factorial. Both experiments were duplicated and analyzed as randomized complete block designs. In Exp. 1, the fractional rate of degradation linearly decreased (P < 0.001) and effective ruminal dry matter degradability (ERD) linearly decreased (P < 0.001) from 80.8% to 60.3% as flake density increased from 257 to 412 g/L. In Exp. 2, storage of steam-flaked corn samples at 55ºC for 3-d decreased (P < 0.001) the fractional rate of degradation and ERD by 38.6% and 21.7% across all feed fractions, respectively. Using data from Exp. 1 and 2, SA of sifted flakes was positively correlated (Pearson = 0.8435; R2 = 0.71; P < 0.001) to ERD. The results of the current study demonstrate that decreased SA resulting from starch retrogradation or increased flake density is associated with decreased ERD. Decreases in SA and ERD may indicate that increasing flake density or starch retrogradation could potentially alter the site of digestion in cattle, by increasing postruminal starch flows.

Pasting Behavior and Viscoelastic Properties of Fresh, Chilled, and Rehydrated Freeze-Dried Gel Beads from Blends of Tapioca Flour, Soy Flour, and Cane Sugar

An extreme vertices design for a mixture of three components was used to establish the proportions of tapioca flour (50% to 100% w/w), soy flour (0% to 50% w/w), and cane sugar (0% to 10% w/w) mass fractions in a food gel bead system. Thus, nine compositions were prepared and analyzed. The pasting profiles of the mixtures were studied using a Rapid Visco Analyzer. The texture profiles of fresh, chilled, and rehydrated freeze-dried gel beads were studied using a texture analyzer. Increasing the proportion of soy flour in the range of 11.25% to 50.00% w/w decreased the peak viscosity, breakdown, final viscosity, and setback of mixed flour. Tapioca flour in the proportion of 81.25% to 100.00% w/w recorded the lowest hardness of fresh gel beads (92.00 to 283.00 g). Soy flour in the proportion of 11.25% to 50.00% w/w exhibited lower texture profiles (hardness, chewiness, and gumminess) than tapioca flour in gel beads for both chilled and rehydrated freeze-dried gel beads. Significant relationships were found among pasting profiles of the flour mixtures and texture profiles of fresh, chilled, and rehydrated freeze-dried gel beads, implying a functional role for soy flour in food gel beads. In conclusion, soy flour can act as an anti-retrogradation agent for the gel beads both in chilled (stored at 4°C for 7 days) and freeze-dried conditions. A small amount of cane sugar does not affect the inhibition of starch retrogradation in the gel bead system. Keywords: Anti-retrogradation, Food gel bead, Pasting profile, Soy flour, Tapioca flour, Texture profiles

The retrogradation characteristics of starch in green wheat product Nianzhuan: effects of storage temperature and time

The objective of this study was to reveal the process of starch retrogradation and quality changes of Nianzhuan stored at 4, −18 °C, and freeze-thaw cycles treatment for different lengths of time. XRD revealed that Nianzhuan starch displayed an increasing trend of crystallinity with prolonged storage time and numbers of freezing-thawing cycles, which was likely due to a more orderly crystalline matrix in starch. The Raman full width at half-maximum (FWHM) of the bands at 2913 cm−1 of the three storage methods all decreased. According to DSC analysis, an increase in ∆H was detected, and a significant (P < 0.05) increase in T o and T p were found at −18 °C, and freeze-thaw treated samples, indicating more thermal energy were needed to disrupt re-crystallization. Good correlations between crystallinity, FWHM, ∆H, and hardness, springiness, chewiness were tested. The results of this study would provide useful information for the process of starch-based product Nianzhuan.

Wheat rheological and Mixolab quality in relation to cropping systems and plant nutrition sources

The objective of this study was to evaluate the effect of cropping systems [integrated (INT) vs. organic (ORG)] and plant nutrition sources (synthetic in INT vs. approved organic in ORG) on analytical and rheological quality traits of winter wheat and its productivity. The results after 16 years of field experiments were evaluated. Pre-crop for winter wheat was N-fixing crop. Grain yield of winter wheat (6.8 t ha^–1 in INT, 6.5 t ha^–1 in ORG) did not differ significantly, while plant nutrition sources had an equal and positive effect on the yield. Crude protein quantity was higher in INT system by about 0.2%. The farinograph dough development time and dough stability were the longest for ORG and fertilised treatments. Mixolab quality indicators showed a clear distinction between ORG and INT systems and fertilisation in the protein and starch characteristics of the grain. The ORG reported longer Mixolab stability of the dough, mainly on fertilised treatment (8.8 min). Starch characteristics – torque C4 (amylolytic activity) and torque C5 (starch retrogradation) were higher for ORG system. Torque C2, protein weakening, was not affected by the cropping system. ORG system has the potential to achieve consistent, high-quality yields with significantly lower reliance on external inputs.