Fadi M. Aramouni

Effects of xanthan–locust bean gum mixtures on the physicochemical properties and oxidative stability of whey protein stabilised oil-in-water emulsions

The effects of xanthan gum (XG)-locust bean gum (LBG) mixtures (0.05, 0.1, 0.15, 0.2 and 0.5 wt%) on the physicochemical properties of whey protein isolate (WPI) stabilised oil-in-water (O/W) emulsions containing 20% v/v menhaden oil was investigated. At higher concentrations, the apparent viscosity of the emulsions containing XG/LBG mixtures was significantly higher (p<0.05) than the emulsions containing either XG or LBG alone. Locust bean gum showed the greatest phase separation, followed by XG. Microstructure images showed depletion flocculation at lower biopolymer concentrations, and thus led to an increase in creaming instability and apparent viscosity of the emulsions. Addition of 0.15, 0.2 and 0.5 wt% XG/LBG mixtures greatly decreased the creaming of the emulsions. The rate of lipid oxidation for 8-week storage was significantly lower (p<0.05) in emulsions containing XG/LBG mixtures than in emulsions containing either of the biopolymer alone.

Physical and sensory characteristics of cookies prepared with flaxseed flour.

BACKGROUND Flaxseed has many health benefits and is considered a functional food ingredient. Flaxseed flour (0-18%) was used to partially replace wheat flour in cookies and its effects on the physical and sensory characteristics of the cookies were investigated. A correlation analysis was conducted between the instrumental and sensory data. RESULTS The cookie dough stickiness significantly (P < 0.05) decreased in relation to higher percentages of flaxseed flour. The 18% flaxseed cookies had the firmest texture, darkest color and lowest water activity. The 18% flaxseed cookies had the greatest spread ratio. However, this resulted in cookies of unacceptable quality properties. In consumer acceptance tests, cookies made with 6% and 12% flaxseed flour had the highest rating among all sensory attributes, while the 18% flaxseed cookies had the lowest sensory scores. The flavor attribute was most highly correlated with the overall acceptability (r = 0.90). CONCLUSION Results indicated that flaxseed flour can be incorporated in cookies as a partial replacement up to 12% of wheat flour without negatively affecting the physical and sensory quality. The correlation results suggest that the flaxseed flavor attributes best predict consumer preference for overall acceptability, though texture and color attributes also contribute.

Effect of HPMC on the quality of wheat-free bread made from carob germ flour-starch mixtures.

UNLABELLED Carob germ proteins have been shown to have functional properties similar to wheat gluten enabling formulation and production of yeast leavened gluten-free baked goods from a true dough rather than a stiff batter. The purpose of this research was to optimize the production of wheat-free bread containing carob germ flour, corn starch, NaCl, sucrose, hydroxypropyl methylcellulose (HPMC), and H₂O. A key criterion was to formulate viscoelastic dough similar to wheat dough. To that end, response surface methodology (RSM) was used to determine optimal levels of carob germ flour, H₂O, and HPMC. Components varied as follows: 4.94%-15.05% for carob germ flour, 0.05%-3.75% HPMC, and 65.25%-83.75% H₂O (percents are on a flour basis, where carob germ flour in combination with maize starch equals 100%). Sucrose, NaCl, and yeast were held constant at 2%. Bread parameters evaluated were specific volume and crumb hardness, where the largest specific volume and the lowest value for crumb hardness were considered most desirable. The optimum formula as determined by RSM consisted of 7% carob germ flour, 93% maize starch, 2% HPMC, and 80% H₂O with predicted crumb hardness of ~200 g of force and a specific volume of ~3.5 cm³/g. When proof time was optimized, a specific volume of ~5.6 ml/g and crumb hardness value of ~156 g of force was observed. Carob germ flour may be used as an alternative to wheat flour in formulating viscoelastic dough and high quality gluten-free bread. PRACTICAL APPLICATION Celiac disease affects approximately 1% of the worlds population. Sufferers of the disease must consume a gluten-free diet. Currently, gluten-free baked products are made from batters and lack the ability to be made from dough based systems which limits the overall processability and product variety. This research is aimed at the utilization of carob germ protein and its ability to form dough to produce an optimal gluten-free bread formulation. This will help to alleviate problems in processability and product variety associated with gluten-free baked goods.

Composition and Molecular Weight Distribution of Carob Germ Protein Fractions

Biochemical properties of carob germ proteins were analyzed using a combination of selective extraction, reversed-phase high-performance liquid chromatography (RP-HPLC), size exclusion chromatography (SEC) coupled with multiangle laser light scattering (SEC-MALS), and electrophoretic analysis. Using a modified Osborne extraction procedure, carob germ flour proteins were found to contain approximately 32% albumin and globulin and approximately 68% glutelin with no prolamins detected. The albumin and globulin fraction was found to contain low amounts of disulfide-bonded polymers with relatively low M(w) ranging up to 5 x 10(6) Da. The glutelin fraction, however, was found to contain large amounts of high molecular weight disulfide-bonded polymers with M(w) up to 8 x 10(7) Da. When extracted under nonreducing conditions and divided into soluble and insoluble proteins as typically done for wheat gluten, carob germ proteins were found to be almost entirely ( approximately 95%) in the soluble fraction with only ( approximately 5%) in the insoluble fraction. As in wheat, SEC-MALS analysis showed that the insoluble proteins had a greater M(w) than the soluble proteins and ranged up to 8 x 10(7) Da. The lower M(w) distribution of the polymeric proteins of carob germ flour may account for differences in functionality between wheat and carob germ flour.

Role of non-covalent interactions in the production of visco-elastic material from zein

The role of non-covalent interactions in the formation of visco-elastic material from zein was investigated. Hydrophobic interactions were evaluated through the addition of various salts from the Hofmeister series. Urea, ethanol, and beta mercaptoethanol (β-ME) were used to evaluate the effects of protein denaturation and disulfide bonds on zeins ability to form a visco-elastic material. The addition of NaI and NaSCN altered the properties of visco-elastic materials made from zein, making them softer and more extensible, as did urea and ethanol. The addition of NaCl and Na2SO4 negatively impacted the ability of zein to from a visco-elastic material and at higher concentrations completely disrupted the formation of visco-elastic material. These results indicate that manipulating non-covalent interactions in zein can alter and in some cases, completely disrupt the formation of a visco-elastic material. Specifically this may be due to disruption of hydrophobic interactions within individual zein proteins or interactions between proteins. The reducing agent β-ME had little effect on zeins ability to form a visco-elastic material. Therefore, the visco-elastic properties of zein arise as a result of non-covalent interactions.

Physicochemical and sensory characteristics of no-bake wheat–soy snack bars

BACKGROUND Health and wellness is a trend observed throughout ready-to-eat cereals, cereal health bars. Therefore, the main objectives of this research were to produce a low cost, acceptable, nutritious and healthy wheat- and soy-based bar under no-bake conditions. Also, the physical, chemical, microbial, acceptability and the nutritional value of this product were studied. Six different bars were produced: a wheat bar (WB), a wheat bar with coating (WBC), a wheat and soy bar with coating (WSBC), a soy bar with coating (SBC), a wheat bar with 3% glycerin (WB3%), and a wheat bar with 6% glycerine (WB6%). RESULTS WB and WBC had the highest water activities while WSBC had the lowest. The three bars with coating had higher L and lower b values, which indicates that they were lighter and not as highly yellow coloured as the wheat samples. WSBC had the lowest value for hardness while the SBC and WBC had the highest. SBC received the highest scores for overall acceptability, appearance, sweetness, flavour and texture while WSBC received the second highest score in all categories. CONCLUSION It appears that consumers prefer the soy varieties to the wheat bars. These types of bars can aid in feeding the general population, which is becoming increasingly concerned with nutrition and convenience.

Effect of sorghum flour composition and particle size on quality properties of gluten-free bread

White, food-grade sorghum was milled to flour of varying extraction rates (60%, 80%, and 100%) and pin-milled at different speeds (no pin-milling, low-speed, and high-speed) to create flours of both variable composition and particle size. Flours were characterized for flour composition, total starch content, particle size distribution, color, damaged starch, and water absorption. Bread was characterized for specific volume, crumb structure properties, and crumb firmness. Significant differences were found (P < 0.05) in the composition of sorghum flours of varying extraction rate, most notably for fiber and total starch contents. Flour particle size and starch damage were significantly impacted by extraction rate and speed of pin-milling. Water absorption increased significantly with increasing extraction rate and pin-milling speed. Breads produced from 60% extraction flour had significantly higher specific volumes, better crumb properties, and lower crumb firmness when compared with all other extractions and flour types. The specific volume of bread slices ranged from 2.01 mL/g (100% extraction, no pin-milling) to 2.54 mL/g (60% extraction, low-speed pin-milling), whereas the firmness ranged from 553.28 g (60% extraction, high-speed pin-milling) to 1096.26 g (commercial flour, no pin-milling). The bread characteristics were significantly impacted by flour properties, specifically particle size, starch damage, and fiber content (P < 0.05).

Effect of flaxseed flour incorporation on the physical properties and consumer acceptability of cereal bars

Extensive research has revealed numerous nutritional and health benefits of flaxseed due primarily to its nutrients content. The objective of this study was to evaluate the effect of flaxseed flour addition on the physical and sensory characteristics of cereal bars. Four formulations of the flaxseed cereal bars were prepared by partially replacing oats with flaxseed flour added at levels of 0 (control), 6%, 12% and 18%. There were no significant differences (p > 0.05) in water activity, moisture and firmness values between the flaxseed bars and control. Flaxseed addition significantly (p < 0.05) decreased lightness and increased redness of the bars. There were no significant differences (p > 0.05) between the 12% flax cereal bars and the control with respect to sensory attributes and overall acceptability. The overall acceptability for both 12% flax bars and the control was in between ‘like moderately’ and ‘like slightly’ on the 9-point hedonic scale. The overall acceptability was most highly correlated with flavor acceptability for both control (r = 0.80) and 12% flax (r = 0.82) cereal bars. Flaxseed bars provided 12% dietary fiber of the daily recommended value. These results indicated that flaxseed flour incorporation up to 12% substantially enhanced the nutritional qualities of the cereal bars without affecting their sensory and quality properties.

Evaluation of sorghum flour functionality and quality characteristics of gluten-free bread and cake as influenced by ozone treatment

Commercially milled food-grade sorghum flour was subjected to ozone at the rate of 0.06 L/min for 15, 30, and 45 min. The pH of ozone-treated flour decreased as exposure time increased. The L* (lightness) values of sorghum flour significantly increased (p < 0.05), while the b* (yellowness) values significantly decreased as ozone exposure time increased. Peak viscosity significantly increased as time of ozonation increased from 0 to 45 min. Results showed that gluten-free cake volume significantly increased as ozonation time increased. Additionally, longer ozonation exposure times increased cells per slice area, lightness, and slice brightness values in gluten-free cakes while reducing crumb firmness. Despite improving lightness and slice brightness values, ozonation did not significantly increase the specific volume of gluten-free batter-based bread. While ozonation improved the volume and texture in cakes, it did not have the same positive effects on gluten-free bread. Bread made from ozonated sorghum flour had an open ragged structure with equivalent volume to the control flour. In both applications, the increased brightness and lightness values due to ozone exposure is recommended to increase the acceptability of sorghum products.

The Effects of Egg and Diacetyl Tartaric Acid Esters of Monoglycerides Addition on Storage Stability, Texture, and Sensory Properties of Gluten-Free Sorghum Bread.

The impact of whole egg addition (as is) at 20%, 25%, or 30% (flour basis) on sorghum bread quality was evaluated. The use of the antistaling agent diacetyl tartaric acid esters of monoglycerides (DATEM) at 0.5% (flour basis) at each of the egg addition levels was also studied. Evaluated quality factors included color, specific volume, and crumb structure. Texture analysis was performed to evaluate the rate of quality loss based on changes in crumb hardness values over time. A trained sensory panel evaluated bread quality attributes by descriptive analysis. Sorghum breads with egg had larger specific volumes than the control, while DATEM had a negative effect on the volume of sorghum gluten-free bread. Inclusion of egg in the bread formula improved cell structure and produced darker crust (P < 0.05). The addition of egg reduced bread hardness and slowed the rate of quality loss over a 12-d storage period. Descriptive analysis confirmed the findings of texture analysis. Control breads were significantly harder (P < 0.05) than egg-containing bread at days 0 and 4. This research demonstrates that addition of eggs to a gluten-free sorghum bread formulation results in improved storage stability and better overall quality and acceptability of the product.