Name Student ID # FST 45/55 Food Systems Chemistry Solids Rheology and Dispersed Systems Lab Week 0 Winter 00 >>>>>><<<<< NOTE: The EGG PRODUCTS made in class are made from UNPASTEURIZED egg yolks. As a result of the potential for salmonella food poisoning from ingesting raw eggs the egg products made in class are NOT TO BE EATEN. Station : Mayonnaise A simple emulsion primer http://www.ifr.ac.uk/materials/fractures/emulsions.html Objectives To study the formation of a common food emulsion mayonnaise. To observe: the changes in material properties between the raw materials and the finished product when making the emulsion mayonnaise. the importance of the order of addition of ingredients the viscoelastic behavior, yield stress, and flow properties [if any] of mayonnaise. the influence [if any] of droplet size on flow behaviors. To determine: viscosity and shear thinning behavior To assess: spreadability by a manual test. qualitative yield stress appearance & color Formulation/Process variants all weights in grams Formulation Egg yolk Vinegar Mustard powder Salt Sugar Canola oil % or % w/w xanthan solution Control 50 5 5 5 00 Reduced fat 50 5 5 5 00 00 (% X) a Reduced fat 50 5 5 5 00 00 (% X) b Reduced fat 50 5 5 5 50 50 (% X) c Reduced fat 50 5 5 5 00 00 (% Guar)
3 Control/all 50 5 5 5 00 in 4 Control hand 50 5 5 5 00 mixed 5 Commercial 6 Commercial reduced fat Procedures For power mixing (variants & ): Put egg yolk in a bowl of the Hobart 5 quart mixer. Add sugar, salt, mustard powder, and vinegar [and xanthan solution for #]. Beat with hand whisk until well blended. Turn mixer to speed 3; add oil very slowly beating continuously. Make sure the mixture is emulsified before adding more oil. For power mixing (variant 3): Put OIL, & egg yolk in a bowl of the Hobart 5 quart mixer. Add sugar, salt, mustard powder, and vinegar. Beat at speed until well blended. For hand mixing (variant 4): Put egg yolk in a glass bowl. Add sugar, salt, mustard powder, and vinegar. Beat at with hand whisk until well blended. Add oil VERY VERY slowly at first beating continuously making sure the mixture is emulsified before adding more oil. As you get through about ½ the oil it can be added faster but still make sure the mixture is emulsified before adding additional oil. For ALL samples Variant Appearance* Color Spreadability** Homogeneity** Texture*** (DO NOT EAT) Yield stress**** yes/no a b c 3 4 5 6 *e.g. glossy, dull, oily, dry, and other descriptors; **see rating scales; ***thick, thin, watery, jelly like, elastic, flows easily, doesn t flow; ****Yield stress, take a spoonful and mound onto the line spread apparatus, does it flow or not, leave for 5 minutes and observe? **Mayonnaise for spreadability** Use a knife to scoop out a small amount of mayonnaise and spread on a flat surface
3 4 5 Very easy Moderately Slightly Not very Not at all easy easy easy easy **Mayonnaise homogeneity** 3 4 5 Very Moderately Slightly Not very Not at all homogeneous homogeneous homogeneous homogeneous homogeneous creamy & smooth lumpy Viscosity [All expect sample 3] Take readings and record MEAN value and standard deviation 5 rpm (factor 4000***) 0 rpm (factor 000) 0 rpm (factor 000) Mean SD Mean SD Mean SD Sample Dial reading Sample Dial reading Sample 4 Dial reading Sample 5 Dial reading Sample 6 Dial reading *** To calculate viscosity in centipoise (cp), multiply the dial reading by the factor corresponding to the viscometer spindle and speed combination utilized. cp = mpa s. You are using Spindle T D Questions:. In mayonnaise, what is the dispersed phase? What is the continuous phase?. Briefly describe how lecithin, the emulsifying agent in egg yolk acts to emulsify oil and water. 3. This is phosphatidylcholine a component of lecithin. Circle and label which part of the molecule would be embedded in the oil phase; the water phase. Why?
4. What causes the mayonnaise to thicken? 5. Why must the oil be added slowly? 6. PLOT using Excel or another spreadsheet viscosity versus RPM for each sample ON A SINGLE GRAPH Station : Stress relaxation Apply these test parameters with the texture meter and the 5 mm flat blade compression probe to all three samples Compress to 0 % @ 0.5 mm/sec, hold at target strain value for 0 sec. Take readings and record MEAN value and standard deviation Sample Peak force @0% strain Residual force % residual force *# % stress relaxation **# Mean SD Mean SD Cookie dough Noodle dough Hunt s SnackPack sugar free gels * % residual force (final force / peak force * 00 ); ***% stress relaxation (00 %residual force) higher values mean MORE stress relaxation; #calculate once from mean values Questions:. Which material had the most elastic behavior which the least how did you make this determination?. What are plausible MOLECULAR LEVEL rationales for the relaxation of stress in each of the materials 3. Look at the ingredients on the SnackPack gels. Strawberry Ingredients: Filtered Water, Less than % of: Fruit Juice from Concentrate (Adds a Trivial a Amount of Sugar) (Water, Apple, Pear, Peach, Pineapple), Carrageenan, Natural and Artificial Flavor, Potassium Citrate, Adipic Acid, Citric Acid, Locust Bean Gum, Sodium Citrate, Sucralose, Salt, Xanthan Gum, Red 40.
4. Go on a quest (the index of Fennema is a good start). What are the most likely ingredient[s] that are forming the gel. What is your rationale for your conclusion? Fennema IVth Ed. a very brief treatment of rheology pp 809 8. Station 3: Brittle versus ductile fracture Stored (> 6 hours @ >80% RH) and fresh cookies and crackers apply these test parameters with texture meter and 3 point bend rig with mm radius flat blade probe 0.5 mm / sec compression 5 kg load cell Take readings and record MEAN value and standard deviation. Calculate distance and strain to fracture from MEANS of time to fracture and sample thickness Sample thick mean SD Peak force Time to fracture * Distance to fracture ** mean SD mean SD STRAIN to fracture *** Cookie fresh Cookie stored Cracker Fresh Cracker stored *time to first catastrophic failure; **time x 0.5 mm/sec; ***distance to fracture/sample thickness Questions:. What sample was HARDEST? What parameter did you use to make this determination?. What sample was MOST ELASTIC? What parameter did you use to make this determination? 3. Using strain to fracture, which was MORE BRITTLE, the fresh cookies or fresh crackers? 4. Did strain to fracture agree with your observation of the brittleness or not of the fresh versus stored samples? 5. WHY was there the observed difference between the stored and fresh cookies and crackers? 6. Would we have had the same problem storing cookies out in the open in Arizona in the summer?
7. Plot the hypothetical path the cookies or crackers took during storage in the accompanying state diagram. Note where the cookies were crunchy and where they were soggy, leathery? Cookie state diagram Station 4: Exploring Egg White Foams >>>>><<<<< Objectives Investigate the influence of acid, sugar and timing of addition on the volume and stability of egg white foams. Explain the observations of the behavior of each foam system based upon the characteristic and interactions of the different ingredients Procedure. For each trial, separate egg whites from the yolk and add to a stainless steel bowl. Set mixer on medium low, and beat egg whites in until air is clearly entrained in the mix. Then increase speed to medium high until foam reaches a maximum volume. Make note of the time it takes to reach this volume. 3. As soon as the beating of each treatment is complete, transfer 00 ml of foam from the bowl to a 50 ml graduated cylinder and let stand for 5 minutes. Then measure the volume of liquid drained from the foam. 4. As the foam collapses, measure the ph of each. In separate bowls prepare each of the following:. Egg whites only. Egg whites + ½ tsp. (5 g) cream of tartar add cream of tartar after 3. Egg whites plus 4 Tbsp. (50 g) of sugar add sugar before beating egg whites 4. Egg whites plus 4 Tbsp. (50 g) of sugar beat egg whites to foamy stage, then slowly add sugar while still beating.
Data Recording Compare the appearance and texture (do not consume raw eggs can transmit Salmonella) of the foams. Treatment Egg whites only (control) + cream of tartar + sugar (at beginning) + sugar (after foam) Time to Max. Volume Rank Order of Volume = most ph Color Volume Relative to Control Texture Drainage (ml) Questions:. Provide a molecular explanation for the order of volume?.which foam appeared to have the smallest gas cells? Why would this be the case? 3.Which foam had the maximum drainage? Minimum drainage? Explain. 4.Were there differences in color? What would result in a shift from a yellow white to a blue white color? 5.How did the two trials that included sugar differ? Interfacial properties of proteins starts P 69 in Fennema IVth Ed.
Materials: Brittle and ductile fracture o Sugar snap cookies and Nabisco Crackers new crispy old soggy Stress relaxation o Preset xanthan/lbg gels o Sugar cookie dough o Noodle dough Egg Whites o 8 eggs, sugar, cream of tartar (Potassium acid tartrate) Mayonnaise o 8 eggs, % w/w xanthan gum solution, vinegar, mustard, sugar, salt Equipment: Mayonnaise o 4 glass bowls, hand and electric whisks or Hobart stand mixer, Brookfield Viscometer, Helipath Stand, and associated sensors, line spread apparatus Brittle and ductile fracture o TA XTPlus texture meter, 3 point bend rig 5 kg load cell, computer, Digital calipers (from bake lab) Stress relaxation o TA XTPlus texture meter, compression rig 5 kg load cell, computer, wire cheese cutter Egg Whites o 4 stainless steel bowls, 4 graduated cylinders 50 ml, Blender, Stopwatches; ph meter >>>>>><<<<<<<>>>>>><<<<<<>>>>><<<<<<>>>>>><<<<<<>>>>>><<<<<< References: () Damodaran, S., Parkin, K. L., and Fennema, O.R. 007. Fennema s Food Chemistry 4th Edition, CRC Press. p66 67; 84 86; () Walstra P. 003. Physical Chemistry of Foods. CRC Press. TP37.5.W355