Mohammad Ganjeh; Seyed Mahdi Jafari; Mohammad Hoseinnejad
Abstract
Introduction: Yogurt is the most frequently consumed fermented milk product with a positive impact on human health due to its high nutritional value. Characteristics such as acidity, amount of free fatty acids with sensory characteristics and nutritional properties of yogurt are very important. Food ...
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Introduction: Yogurt is the most frequently consumed fermented milk product with a positive impact on human health due to its high nutritional value. Characteristics such as acidity, amount of free fatty acids with sensory characteristics and nutritional properties of yogurt are very important. Food fortification is defined as addition of one or more essential nutrients at levels higher than naturally presence in food products. The World Health Organization estimates that at least 1 of every 5 people in the world suffer from lack of iodine, zinc, iron, folic acid, calcium, vitamin A and B. The aim of this study was to evaluate the changes in physicochemical, textural and sensory properties of iron and zinc enriched yogurt during the shelf-life period and to assess the extent and the effect of these supplements on these properties.
Materials and methods: To perform enrichment, milk was divided into seven parts: 3 containers for fortification with iron, 3 containers for fortification with zinc and 1 container as the control sample. Fortification with iron and zinc was performed by concentrations of 20, 40 and 60 mg per kg of milk (according to the daily requirement of iron and zinc). The samples were then transferred into the container of 100 grams which were incubated at 45 °C, and after reaching the pH of 4.4 to 4.5, they were transferred to cold storage at 4 °C. To investigate the effect of enriching on the produced yogurt properties, the samples were evaluated after a period of one, seven and fourteen days. The syneresis of yogurt samples was determined by Salvador and Fiszman (2004) method, with slight modification. Water holding capacity was determined by centrifuge (Hettich Universal 320R - Germany) as reported by Sahin et al (2008) with slight modification. The acidity of the yogurt samples was measured by Kim and Lee (2002) method based on the percentage of lactic acid. Sensory characteristics of our samples in terms of taste, odor, color and texture and overall acceptability were evaluated by 12 Panelists (6 males, 6 females, 45- 21 years) by using a five-point hedonic test. Texture analysis was performed using Texture Analyzer (Brookfield Model CT3 Texture Analyzer – USA) based on Supavititpatana et al (2008) method.
Results & discussion: Syneresis of product decreased from 0.24 to zero in yogurt samples containing iron and from 1.20 to 0.81% in zinc treatments. Increasing the storage time in the presence of iron causes a sharp decrease in the amount of the syneresis up to zero. The main reasons for syneresis in fermented products include high incineration temperature, low total solids and inadequate storage temperature. The water holding capacity of the product was shown a relatively increase over time and the highest amount was observed in the treatments containing high concentrations of iron during the early days of storage, while at the same high concentrations in the final days of storage, the lowest water holding capacity was observed, which could be due to the adverse effect of the storage time on this factor. The viscosity increased over time, and the rate of increase in the early days was far higher than the final days (in both iron and zinc treatments). In iron and zinc treatments respectively, water holding capacity increased from 50.08 to 55.50, and 43.57 to 55.47 % and viscosity from 855.55 to 961.11, and 677.78 to 833.30 mPa s. By analyzing data obtained from texture analyzer, important properties such as firmness and springiness increased and the lowest cohesiveness and the highest adhesiveness were observed in the middle of storage time. Both iron and zinc treatments increased the hardness of the product compared to the control samples and the amount of this increase in iron containing yogurt samples was slightly higher than that of zinc. In both treatments, there was a significant decrease in the product adhesion force compared to the control sample. In contrast, the highest continuity of product was observed in the middle days of the storage period.The highest levels of flavor were detected on the seventh day of storage, and changes in the zinc and iron content of the products were almost ineffective in the desirability or taste loss, and only control samples were evaluated with a little higher flavor than other treatments. Sensory properties were not significantly different (P
Amin Rangriz; Seyed Ali Mortazavi; Morteza Khomeiri; Soheil Amiri
Abstract
IntroductionTraditional mayonnaise is probably one of the oldest and most widely used sauces in all over the world. Mayonnaise is a product with particular consistency and is classified as a type of oil in water emulsions. Vegetable oil, acetic acid, and egg yolk are main components of mayonnaise. In ...
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IntroductionTraditional mayonnaise is probably one of the oldest and most widely used sauces in all over the world. Mayonnaise is a product with particular consistency and is classified as a type of oil in water emulsions. Vegetable oil, acetic acid, and egg yolk are main components of mayonnaise. In addition, mayonnaise may contain salt, sweeteners, spices, effective flavor materials, preservatives and stabilizers. It must contain at least 78.5 % of total fat and 6 % pureegg yolk. Due tohigh levels of oil present in mayonnaise, continuous usageof this product may result in diseases such as obesity,arteriosclerosis, hypertension and cardiovascular diseases.Therefore, consumers tend to consume low-fat products.Yoghurt is a very useful fermented milk products in terms of lactic acid bacteria that have beneficial effects on human health and Because of the similarity between this productand mayonnaise in terms of rheological properties, Yoghurt have been selected as a fat mimetic in mayonnaise.Therefore, the objective of present study was to investigate the effects of partial fat substitutionby yoghurt on physicochemical, rheological and sensory properties of low fat mayonnaise.Materials and methodsMayonnaise preparationOne kilogram of each mayonnaise sample was prepared.Different recipes of mayonnaise contained yoghurt asfat mimetic (as % of oil and yoghurt) including (49.5 % & 25%), (33% & 50%), (16.5% & 75%). All formulations contained 13 % Egg yolk, 10 % Vinegar, 1 %Mustard, 1 % common salt ,4 % sugar , sodium benzoate 0.07 % , Xanthan gum 0.2%.Mayonnaise preparation procedure was as follows; firstlyegg and vinegar were mixed together and then all otherIngredients(including Yoghurt for the low fatmayonnaise recipes) except oil were added and mixed well. The oil was finally poured insidethe mixer very slowly and homogenized for 1 min. Subsamples (250 g) of mayonnaise were aseptically transferredto sterile 250 ml, Duran glass bottles withpolypropylenescrew caps and left for one-day at 5 °C.Proximate composition analysisMoisture, protein, and ash contents were determined accordingto AOAC (2005) official methods. Fat content wasmeasured by Bligh and Dyer (1959) method, and totalcarbohydrate content was calculated by difference.Rheological measurementsRheological measurements were performed after 24 hstorage using a Brookfield viscometer Model RVDV-IIwith aspindle no.6 at 5 °C and 25 °C. Shear stress data wereplotted versus shear rate for each mayonnaise sample ata range of spindle speed (10–200 rpm). Plots of Lnshear stress versus Ln shear rate (for each sample) werethen used to calculate values including flow behaviorindex (n) andconsistency coefficient (K).Texture analysisMayonnaise samples were stored in refrigerator for 24 huntil texture analysis. The measurements were carriedout using a Brookfield texture analyzer (BrookfieldLFRA texture analyzer model number 4500 texture prolite) equipped with a 38 mm diameter cylindrical probeat 25 °C.The condition of the analysis was as follows; one cyclewas applied, at a constant crosshead velocity of 1 mm/s to asample depth of 30 mm, and then returned. From the resultingforce-time curve, the values for texture attributes, i.e.firmness, adhesiveness, and consistency were obtained usingtexture pro lit software.pH measurement and stability testpH was determined using AOAC standard method at 25 °C. The samples were assessed for the stabilitytest after 24 h storage at 35 °C. Mayonnaise stability wasdetermined after centrifugation (10 min, 2,500 rpm), andwas expressed as the volume of separated phase to the totalemulsion volume.Color measurementMayonnaise samples were measured for color in the L*, a*,b* system using a Lovibond Colorimeter.Sensory analysisAfter 1 day storage Sensory characteristics including appearance,color, odor, texture, taste, and overall acceptabilitywere evaluated by 14 semi-trained panel on 5-point hedonicscale (1 = the least or the lowest; 5 = the most or thehighest).Statistical analysisAll the tests were performed in triplicate. The data collectedwere analyzed by one-way analysis of variance (ANOVA),and significant differences of means were compared usingDuncan test at 5 % significance level using SAS softwareprogram.Results and Discussion: In present study, physicochemical, texture, sensory and rheological properties were evaluated in mayonnaise formulation with dairy-based. Fat was partially substituted by yoghurt at levels of 25, 50 and 75% which were referred respectively as SM1 (25% fat substitution level), SM2 (50% fat substitution level) and SM3 (75% fat substitution level) and the full fat mayonnaise (S) with 66 % oil was used as control sample. Results indicated that low-fat mayonnaise samples had considerably lower energy content compared with control sample, but higher water content than it. In terms of texture, SM3 had lower hardness compared with control sample. The samples exhibited thixotropic and shear thinning behavior through rheological studies and all samples were classified in the group of solid viscoelastic materials because, in all samples, storage modulus was greater than loss modulus. Also, the loss tangent of low-fat mayonnaise samples were higher than the control sample which reflects the tendency of these samples behavior to pseudo-liquid behavior. Results of sensory evaluation demonstrated that SM2 and SM3samples, were more acceptable. It was concluded that yoghurt can be used as a suitable fat replacer in mayonnaise formulation.
Asal Gachpazian; Sodeif Azadmard Damirchi; Javad Hesari; Seyed Hadi Peighambardoust; Mahbub Nemati; Sadegh Alijani; Effat Ahmadi
Abstract
Milk and dairy products are in diet almost every day. Milk fat contains 70% of saturated fatty acids which can cause an increase in total and low-density lipoprotein cholesterol, and the risk of cardiovascular diseases. Therefor, modification of fat composition at dairy products such as yoghurt seems ...
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Milk and dairy products are in diet almost every day. Milk fat contains 70% of saturated fatty acids which can cause an increase in total and low-density lipoprotein cholesterol, and the risk of cardiovascular diseases. Therefor, modification of fat composition at dairy products such as yoghurt seems necessary. Walnut has high amount of essential fatty acids, anti oxidants and other beneficial components. In this study, ground walnut is added to yoghurt at level of 0 (control sample), 3, 6 and 9% and their texture properties (synersis and viscosity), sensory, fatty acids profile and dry matter were analysed every week for 4 weeks during storage. Results showed that fortification of yoghurt samples with ground walnut and storage had significant effects ( ) on synersis, viscosity, fatty acids profile and dry matter. Control sample had the highest synersis and the lowest viscosity and dry matter among samples. By adding ground walnut to yoghurt samples, the amount of saturated fatty acids decreased and the amount of unsaturated fatty acids increased. Major fatty acids of yoghurt incorporating ground walnut were linoleic acid, oleic acid, linolenic acid, palmitic acid and stearic acid, respectively. The highest final score in sensory evaluation in 1, 14 and 28 days of storage time were for yoghurt samples with 9% of gorund walnut, yoghurt with 6 and 3% of ground walnut and yoghurt with 3% of gorund walnut, respectively. Results of this study showed that adding ground walnut modifies yoghurt fat composition, forify it with essential fatty acids and also has good effect on its texure properties.
