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RESEARCH REVIEW REPORT

LIPIDS

JESSICA LEIS

KNH 404

SEPTEMBER 12, 2012

Research Review Report KNH 404

Suzuki, A., Lee, J., Padilla, S., & Martini, S. (2010). Altering functional properties of fats using power ultrasound. Journal Of Food Science, 75(4), 208-214.

Background/Need for Research

Trans fatty acids are widely and frequently used in the food industry because of their exceptional functional properties and their ability to increase shelf time. Despite these properties, trans fatty acids negative impact on the nutritional aspects of foods. Therefore, scientists have set out to find alternative lipid sources to provide the same adequate functional properties for foods previously containing trans fatty acids with positive health benefits. To do so, these researchers have studied the effect of power ultrasound on crystallization behavior of fats as a means of discovering new lipid sources to use. Ultrasound techniques are those that use sound waves using frequency just above human hearing detection, or greater than 20 kHz. In this study, researchers used power ultrasound, or high frequency ultrasound (HIU) at a range of 20 to 100 kHz to examine its ability to change the physiochemical properties of lipid materials. High frequency ultrasound can be used for generating and inducing chemical reactions to alter lipid crystallization behaviors and therefore alter functional properties. The overall objective of this study was to use HIU to evaluate its effect on functional properties such as hardness, amount of crystalline material, and melting behavior of anhydrous milk fat (AMF), palm kernel oil (PKO), and all-purpose shortening (Sh) as a means to determine if alternative lipid sources could provide the same functional properties as trans fatty acids.

Procedure

Several different forms of experimentation and measurements were used during this experiment. Crystallization experiments were first performed with the three testing materials: anhydrous milk fat (from here on, AMF), palm kernel oil (PKO), and all-purpose shortening (Sh). These materials were first crystallized at a fast cooling rate of 10 degrees Celsius per minute at different crystallization temperatures. The samples were heated to 80 degrees Celsius and kept at this temperature for 30 minutes to allow time for complete triacylglyceride melting. The samples were then placed in a double-walled thermostatized crystallization cell with a magnetic stirrer (at 200 rpm) that was constantly stirring during cooling. Crystallization kinetics with sample temperatures were monitored for all samples. When the AMF, PKO, and Sh samples reached their final cooling temperatures, stirring was stopped and high frequency ultrasound (HIU) waves were applied. HIU was applied using a Misonix S-3000 sonicator operating at an acoustic frequency of 20 kHz for 10 seconds using 50 watts of electrical power; a microtip of 3.2 millimeters in diameter was used to sonicate samples that resulted in acoustic powers of 62, 58, and 80 watts for AMF, PKO, and Sh. For the PKO and Sh samples, a second set of HIU acoustic waves was applied when the first crystals were observed with the naked eye. Samples were kept under HIU and at final cooling temperatures for 90 minutes. After time elapsed, the crystallized material was sampled to determine, hardness, melting profile, and amount of crystallization.

A polarized light microscope (PLM) was used to examine crystallization kinetics as well. When the experienced observer first noticed crystallization formation, a drop of liquid was placed in a thermostatized slide with cover slide and observed. The PLM was also equipped with a digital camera. Observations were taken every five minutes during the 90-minute cooling time


frame. Another instrument, the DSC-2910, was used to determine the melting profile of the crystallized lipids in the samples. After 90 minutes at final cooling temperature, 7 to 15 milligrams of the crystallized material was placed in an airtight aluminum pan and immediately placed in the DSC. An empty aluminum pan was used as a reference. The samples were kept at final cooling temperature for five minutes to stabilize the signal and were then heated to 60 degrees Celsius at a rate of five degrees Celsius per minute. The melting property was calculated from the melting endotherms and the parameter was used to evaluate degree of crystallization of the samples. Melting profile of the crystal network was calculated as a percentage of solid fat at different temperatures during melting.

Texture profile analysis for hardness of the crystallized fats was also conducted using a TA-XT plus Texture Analyzer. After being kept at final cooling temperature for the 90-minute time frame, the samples were placed in cylindrical tubes (one centimeter in diameter) and stored at five degrees Celsius for 24 hours. For measurement of texture profile analysis, the samples (now solid) were cut flat into one-centimeter length cylinders. A one-centimeter diameter cylindrical probe was calibrated with a two-kilogram load to be used. Samples were compressed at a constant speed of five mm/s using a compression strain of 25 percent. Hardness was defined as the maximum peak force obtained during the first compression. Melting point determination was determined using the AOCS Official Method Cc 3-25. The melting points used were: AMF at 32.4 ± 0.6 ◦C, PKO at 32.9 ± 0.3 ◦C, and Sh was 35.1 ± 0.4 ◦C.

Experiments were run three times. Results reported are mean values and standard deviations. Significant differences (α = 0.05) were evaluated using a one- and two-way ANOVA with Bonferroni’s posttest using GraphPad Prism version 4.00.

Results

Experimentation demonstrated that, for AMF, HIU could successfully induce crystallization and smaller crystal size. However, this effect strongly depended on supercooling. It was observed that lowering the duration of the ultrasound application and lowering the ultrasound power resulted in more crystallization and formation of smaller crystals. The supercooling of the system, crystallization temperature, duration of ultrasound pulse and the moment at which ultrasound is applied all play important roles in induction of crystallization based on the AMF results.

PKO was tested on the same basic principles. For PKO, more, smaller crystals were obtained when HIU was applied, indicating induction of lipid crystallization. These results correlate with previous data suggesting that ultrasound has the ability not only to induce fat crystallization but to promote formation of smaller crystals (Suzuki, 2010). This means that possible changes in texture may occur to due alteration of the final crystal network.

Based on the same basic principles mentioned above, Sh crystals obtained were also smaller. These crystals were significantly smaller than those for PKO; the decrease in size was also attributed to HIU application.

In reference to hardness, harder materials are expected due to decrease in crystalline size and structure. PKO hardness decreased the most, followed by AMF and then Sh. As expected, the hardness of the samples (crystallized without HIU application) decreased as crystallization temperature increased. The increase is more significant at higher crystallization temperatures. No tendency in hardness values as a function of crystallization temperature was noticed. These results suggest that no further crystallization can be achieved, even if supercooling is increased


or the crystallization temperature is decreased. This means that HIU could be used in AMF systems to generate harder materials in shorter amounts of time without the need of lowering temperature or increasing supercooling. PKO crystals were smaller but the texture was not highly affected by HIU application. However, after the second wave of HIU, a harder sample was observed. This may suggest that there is an “optimum crystal size reduction” value (Suzuki, 2010). A similar behavior was observed for Sh, with a more pronounced effect.

To obtain enthalpy (the energy absorbed form the lipid crystals when they melt) and the melting profile, samples of the crystallized materials were obtained 90 minutes after the start of the experiment. Enthalpy depends upon the degree of crystallization of the lipid. For AMF controls, the higher the temperature, the lower the enthalpy and therefore the lower the amount of crystallized material. This was due to the sizes of the crystals, not the amount of crystallized material. Enthalpy also increased upon crystallization conditions for PKO, meaning HIU is promoting crystallization. No significant differences in enthalpy values were observed for Sh samples when HIU was applied.

Implications

The lipid melting profile of a lipid network depends on the amount of crystallized material and the size of the crystals. The melting behavior of lipid networks is important because it is related to mouthfeel and palatability. The higher the melting profile, the better these properties are. AMF crystallized with HIU had a similar solid/liquid profile as AMF crystallized without HIU, but had a lower percentage of solids at any given temperature, leading to a steeper and sharper melting profile. This may be contributed to smaller crystals obtained after HIU application. PKO samples that were subjected to HIU melted faster, suggesting that despite smaller crystals, the packing of the crystals contributes to a broader melting profile. Sh showed a melting profile similar to that of AMF; sonicated samples melted fast, indicating a lower percentage of solid fat at a constant temperature.

This study indicates that high frequency ultrasound methods have the potential to become an additional processing tool to modifying the textural, structural, and melting properties of lipids to provide a healthier alternative to trans fatty acids used in shortenings. Further testing is needed to determine which products have the best physiochemical properties for altering. Anhydrous milk fat, palm kernel oil, and all-purpose shortening are only a few of the many lipid sources that are used on a regular basis in the food world. HIU needs to be tested on other lipid sources to test in which products trans fatty acids can be replaced or altered without harming the functional properties of the products.


Lin, X., Wu, J., Zhu, R., Chen, P., Huang, G., Li, Y., & ... Ruan, R. (2012). California almond shelf life: Lipid deterioration during storage. Journal Of Food Science, 77(6), 583-593.


This study was designed to look at the effect of storage conditions on the lipid deterioration of California almonds nuts, whole and sliced. Almonds have high levels of unsaturated fatty acids, making them susceptible to lipid oxidation. Almonds are very sensitive to respiration rates, therefore too much respiration from inappropriate storage conditions can have detrimental effects. From this, lipid oxidation occurs, contributing to loss of flavor, color, nutrient value, functionality, and accumulation of compounds that can be detrimental to health. This lipid deterioration can occur through enzyme-catalyzed hydrolytic cleavage, where moisture content is higher than the critical level causing activated enzymes to slice the lipids, or atmospheric oxygen driven oxidative lipid cleavage, which requires oxygen – light, heavy metals, and heat enhance these oxidative reactions. In this experiment, changes in moisture content, mold growth, and textural properties of almonds under different temperature, humidity, and packaging conditions were observed. Examining the correlation between lipid oxidation and moisture contents of the almonds as well as the effect of temperature lipid oxidation was the researchers main focus.

Procedure

The initial moisture content, oil content, and texture of the almond samples were determined prior to starting experimentation. Two types of almonds were used: California and nonpareil. Types of almonds samples included: one pound nonpareil whole, raw almonds sealed in a polyethylene (PE) bag, one pound nonpareil raw almonds in a carton with no PE liner, one pound California whole, blanched almonds sealed in a PE bag, and one pound California regular, sliced blanched almonds in a sealed PE bag. These samples were stored in temperatures ranging from 4.4 degrees Celsius to 38.8 degrees Celsius a total of nine different times. Samples for water content, peroxide value (PV), free fatty acid content (FFA), and iodine value (IV) were taken periodically throughout the experiment. Some treatments did not last because of spoilage at high temperature and/or high humidity.

To determine water content, a weighed almond sample was placed into a clean and dry container with a lid. The total weight of the sample and container with lid was recorded. The sample and container (lid removed) were placed into a drying oven at a temperature of 105 to 110 degrees Celsius. The sample and container with lid were weighed during the drying until they reached a constant weight. A formula was followed to determine these numerical values.

Oil was extracted from the almond samples for analysis of PV, FFA, and IV. To extract the oil, researchers pressed about 300 grams of each sample. Oil extracted was stored in a 50 mL flask at 40 degrees Fahrenheit before analysis; all analyses were completed within one day of oil extraction.

A complex series of liquid additives and titration was conducted to determine PV values. Upon addition of all but one chemical, the solution was shaken vigorously in an Erlenmeyer flask until it turned a faint blue color. The final additive, sodium thiosulfate, was then dropped into the liquid solution until the blue color disappeared. The final product was used in a


standardized calculation for determining PV as mEq of peroxide per kg of oil. A similar procedure was performed to determine IV of oil samples. The final product was calculated using a standardized formula. Again, throughout a complex series of liquid and chemical addition, FFA content was determined as well.

Lipase activity was determined through a series of steps. A 0.01 gram almond sample, one mL of oil, and one mL of phosphate buffer were added to a mortar, ground with quartz sand into a fine paste and then transferred to an Erlenmeyer flask. The mortar was washed with one mL of water (several times) to pool all of the liquid; the flask was then sealed and incubated. The flask was incubated at 4.4, 21.1, and 37.8 degrees Celsius for 24 hours. Upon time lapse, 50 mL of ethanol and ether mixture were added to the flask, which was then shaken and allowed to stand for one to two minutes. The mixture was filtered into another flask where 25 mL of filtrate, three to five drops of phenolphthalein indicator, and titrated 0.05NKOH solution was pipetted into it. Using this final solution and numerical data, a standardized formula was used to calculate lipase activity of each sample.

Statistical analysis and computation of data was performed using Microsoft Excel. All of the data were averaged values of three repetitions. Standard deviations and coefficients of variation were calculated for all data.

Results

Peroxide values in the natural samples did not change much. PV values of blanched samples were higher and did show change during storage. Because of the blanching, these samples had much lower enzyme activity than did the natural samples. These changes may be attributed to the protective almond skins, which act as an oxygen barrier. Overall, the PV values increased with increasing storage temperature. With higher relative humidity, there were fewer changes in PV values. This may suggest that high humidity reduces exposure of lipids to oxygen.

Iodine values indicate the degree of unsaturation in oil; therefore, a higher IV presents a higher potential for oxidation and rancidity. Storage time fluctuated greatly for these values, therefore terminating further observation. However, it seemed that IV seemed to decrease faster at higher storage temperature and humidity and that blanched samples decreased faster than raw samples.

In general, FFA values increased with increasing storage time, temperature, and humidity. Highest levels of FFA were observed in the samples stored at high temperature and high humidity. At low to medium temperatures, values only slightly increased in comparison to higher temperatures, in which the values dramatically increased, even with relatively low humidity. This suggested the importance of temperature in FFA values of the almonds.

Lipase activity for whole, raw nonpareil almonds doubled when temperature was raised from 4.4 to 21.1 degrees Celsius and then increased by 20 times when increased to 37.9 degrees Celsius. FFA content also increased with increasing humidity. This increasing humidity showed that relative humidity dictated the moisture movements and moisture contents. This positive correlation suggests that increased moisture content favored enzymatic reactions.

When comparing samples with whole, raw nonpareil almonds in a sealed bag with PE to the second sample of whole, raw nonpareil almonds in a container with no PE, it was noted that moisture absorption was affected. At medium or high relative humidity, the unpackaged almonds absorbed more moisture than those that were PE packaged. At lower relative humidity, the almond sample without packaging lost more moisture than the PE packaged sample.


The blanched samples followed similar trends as mentioned above, but in lower levels. This could potentially be contributed to lower lipase activity from blanching. Lipase was not totally inactivated by blanching and its activity increased dramatically with increasingtemperature. Despite having the lowest lipase activity, the final sample of California, sliced almonds followed the same trend.

Implications

Overall, it was found that the peroxide values in the raw almond samples did not change much in comparison to blanched samples, which changed dramatically. Skins may have played an important role in preventing oxidation here; blanched almonds had little protection against this autooxidation. This implies that oxidation is reduced when skin is left on the nut and enzymes are not deactivated from blanching. The iodine values decreased slightly in the first period of storage and then began to level off. Almond samples that were nonpareil, whole and raw (with and without PE lining) had higher FFA levels than the California blanched almonds (whole and sliced, both with PE lining). This may have been contributed to inactivated enzyme activities in the blanched almonds compared to the whole. In general, FFA increased with storage time, temperature and humidity. Storage time should be kept to a minimum to reduce the level of lipids. Temperature and humidity should be carefully controlled in almond storage as well to prevent this from happening.

It was also concluded that FFA’s contribute little to PV in almonds, indicating that FFA is not a reliable indicator for rancidity on its own. Several factors must be examined in all future experimentations with almond rancidity.


Rodríguez-Carpena, J., Morcuende, D., & Estévez, M. (2011). Partial replacement of pork back-fat by vegetable oils in burger patties: Effect on oxidative stability and texture and color changes during cooking and chilled storage. Journal Of Food Science, 76(7), C1025-C1031.


This study examines the potential nutritional and technological benefits of replacing animal fats with vegetable oils in cooked and chilled pork meat patties. To extend shelf life, burger patties are chilled during distribution and for display at grocery stores, creating the opportunity for chemical and structural changes to occur within the lipids and proteins, diminishing quality. The technological and appropriateness of using porcine back-fat contributes high amounts of saturated fatty acids (SFA) and cholesterol. The replacement of this animal fat with vegetable oils decreases these amounts. Therefore, the researchers in this study focused on examining the impact of partial back-fat replacement (50 percent) with avocado (A), sunflower (S), and olive oil (O) and their affect on chemical composition, oxidative stability, color, and texture of porcine burgers subjected to oven cooking and chilling.

Procedure

Four types of pork burger patties were prepared using either A, S, or O oils. A control batch (C-patties) of pork back-fat burgers with no added oil was used as well. The patties in the control batch were made using 700 grams meat, 180 grams distilled water, 100 grams back-fat and 20 grams sodium chloride. Those prepared with oils followed the same ingredients list, however 50 percent of the back-fat in the patties was replaced with each of the oils. All ingredients were minced using a Stefan UMC 5 Electronic cutter at 10,000 rpm for five minutes or until a homogenous emulsion-type raw batter was formed. A total of 18 patties were formed. Patties were formed using a conventional patty maker to give average dimensions of 10 centimeters in diameter and one centimeter in thickness. Patties were further divided into three groups: raw(R), cooked (CO), and chilled (CC).

CO patties were cooked at 170 degrees Celsius for 18 minutes in a forced-air oven. Patties were cooked to an internal temperature of 73 degrees Celsius. After cooking, patties were cooled and placed in a refrigerator with the raw patty samples. The following day, R patties were observed for chemical composition and instrumental color and then frozen at -80 degrees Celsius for four weeks. CO samples were also analyzed for their cooking loss, instrumental color and texture and then frozen at the same temperature for four weeks. CC patties were cooked in the same manner as the CO patties and were then placed in polypropylene trays wrapped in PVC film and stored for 15 days at five degrees Celsius under white fluorescent light to simulate retail display conditions. Upon time lapse, the CC samples were analyzed for color, texture, and storage loss. They were then frozen at the same temperature as the CO and R patties for just under four weeks.

Moisture and total protein contents were determined using official methods. Analysis of polyunsaturated fatty acids (PUFA) was done using a gas chromatograph. Total protein carbonyls were determined by derivatisation with dintrophenylhydrazine; protein concentration was calculated from absorption at 280 nm using bovine serum albumin as standard. Volatile compounds were analyzed from the R, CO, and CC burger patties by using the solid-phase micro


extraction (SPME) and gas chromatography/mass spectrometry (GC/MS). The compounds were tentatively identified by comparing their mass spectra with those from the Wiley library or by positively identifying comparison of mass spectra and retention time with displayed standard compounds. Texture profile analysis was also performed. Samples were compressed to 40 percent of their original height with a five-centimeter probe and cross head speed of five mm/s by a Texture Analyzer TA-XT2i. Surface color measurements were conducted using a Minolta Chromameter CR-300. Before each measuring session, the chromameter was calibrated on the CIE color spaced system using a white tile. These measurements were made in triplicate and at room temperature.

A total of six burger patties per oil and processing treatment were used. A one-way analysis of variance (ANOVA) and Tukey tests were used to study the effect of the vegetable oil replacement on chemical composition, texture, and color. Data analysis was performed using SPSS for Windows.

Results

Replacing 50 percent back-fat with vegetable oils reduced the amount of SFA by about 12 percent. O-patties contained the highest amounts of monounsaturated fatty acids (MUFA), followed by A-patties, C-patties, and S-patties. The highest amount of PUFA was found in S-patties, followed by A-patties, C-patties, and O-patties. Replacing the back-fat with oils had no effect on cooking yield.

Cooked and chilled patties, overall, saw a decrease in PUFA of about 4.4 percent. Significant decreases were most noticed in C and A burger patties after cooking and chilling. This could be attributed to heat-induced changes in muscle components, disrupting cell compartmentalization and exposing membrane lipids to a favorable oxidative environment. The degree of unsaturation in oils should have predicted susceptibility to oxidation, however, patties enriched in PUFA (S and O-patties) showed less intense loss of PUFA than control patties. This may be attributed to the presence of antioxidant compounds in the oils that could have enhanced the stability of the treated patties against oxidative reactions.

Thiobarbituric acid reactive substances (TBA-RS) are used to indicate the level of lipid oxidation in products. All R-patties increased significantly in TBA-RS numbers as a result of cooking. The protective effect of vegetable oils against oxidation could again possibly be attributed to antioxidant components. The use of these oils seem to show an efficient way to diminish adverse effects, like rancidity, caused by lipid oxidation in meats. Weak coupling between protein and lipid oxidation was shown through evaluation of protein carbonyls. The substitution did not affect the accumulation of protein oxidation products in the samples.

Hexanal was the most abundant lipid-derived volatile in all meat samples. This compound is a key indicator of lipid oxidation and rancidity. The cooked patties with A oil were significantly lower than those from the control group. The volatiles profile exhibited by cooked and chilled patties was linked by their fatty acid composition as A- and O-patties (containing the largest amounts of oleic acid and MUFA) and their high counts of octanal and nonanal as well. These compounds could reflect a more pleasant odor profile in these burgers as opposed to C- and S-patties.

Hardness in the freshly cooked and chilled patties did not show significant changes in textural properties. This could be attributed to loss of water during storage, among other factors. However, in regards to color, changes were noticed. The small oil globules in the samples reflect


more light because of the larger surface area than the beef fat globules. Cooking and chilled storage of the oil patties increased lightness in color. In regards to redness, the raw control patties were of a deeper color. At all stages, *alpha-values were found in A-patties. This could have potentially been attributed to the large amounts of polyphenols, pigments, and chlorophylls present.

Implications

This experiment has shown that the usage of avocado, sunflower and olive oil as replacements for back-fat in burger patties enhances oxidative stability during cooking as well as in chilled storage. This replacement strategy has a positive outlook for enhancing nutritional quality and oxidative stability of the meat patties bought in supermarkets. This would prolong storage time while maintaining quality. No major detrimental color or texture change was noted in the experiment as well, again positively attributing to grocery store holding. Further analysis will need to be conducted to determine exact nutritional benefits, but vegetable oils are a definite option for replacement of animal back-fat without unfavorable effects on color, texture, and oxidative stability.


Research Content Questions

1. What specific topics are addressed in the research? Replacing back-fat in porcine burgers with avocado, sunflower, and olive oils in

comparison with a control to examine the effect on chemical composition, oxidative stability, color and texture after oven cooking and chilling

Abrasion of hulless barley kernels (fines, kernels and ground kernels) at different levels of removal stored at varying storage temperatures and humidity to analyze levels of oil, free phytosterols, tocopherols and tocotrienols and at what levels these variables were at highest composition

Investigate possible formation of trans fatty acids in ground beef and frankfurters as a result of irradiation and storage at different doses and temperatures

Producing interesterified fats with trans-free substrates of fully hydrogenated soybean oil, extra virgin olive oil, and palm stearin in varying weight ratios at varying temperatures to test potential replacement of the conventional hydrogenation process with trans fatty acids

Examining the effects of storage conditions on the lipid deterioration in California and unpareil almond nuts, whole, sliced, and/or blanched at different combinations of temperature and relative humidity levels

Investigating the effect of green tea extract on biscuits lipid fraction oxidation stability by examining antioxidant effects at different levels

Evaluate the effects of added pyruvate on enhanced beef color stability by assessing the role of pyruvate in lipid oxidation and direction interaction between pyruvate and beef myoglobin

Using ultrasound to test the effect of high intensity ultrasound waves on the functional properties of anhydrous milk fat, palm kernel oil, and all-purpose shortening

Comparison of temperature-induced destabilization of the dispersed phase in butter and margarine by assessing changes in droplet size, solid fat content, and fat crystal organization

Evaluation of the effect of antioxidants on oxidative stability of extruded jerky-style salmon snacks using rosemary, mixed tocopherols, tertiary butylhydroquinone, and ascorbyl palmitate to assess total fatty acid composition, lipid content, moisture, water activity, pH and salt

Examining ground beef lipid oxidation and total volatiles under irradiation with varying fat levels and added degrees of ascorbic acid, alpha-tocopherols and sesamol

Identifying parameters of heating rate, dielectric factors and specific heat capacity of precooked pork patties during different wattages of microwave heating

Determining the effect of different concentrations of citric acid and calcium ions on protein yield, color, and lipid removal from protein isolates of mechanically separated turkey meats

2. What specific objective measurements were used in food evaluation? Acid-aided protein recovery from mechanically separated turkey meat Lipid extraction via homogenization using Power Gen 1000S1, Fisher Scientific Whatman No. 1 filter paper


Thiobarbituric acid reactive substances (TBA-RS) in triplicate for extraction Direct spectrophotometric measurement UV-visible spectrophotometer (V-530, Jasco Corporation) Statistical analysis

o Triplicate runs o Analysis of variance performed with SAS software o JMP software, version 5 for calculation of means and standard deviation o ANOVA (analysis of variance) o STATISTICA 7.1 software o GraphPad Prism version 4.00 o Tukey testso Split-plot randomized complete block design

Laboratory electrical seed scarifer machine Airtight incubator Cyclone Sample Mill with mill enclosures, vacuum system, and sieve Extractions

o Oil yield o Folch method (lipid)

Folin-Ciocalteu’s reagent with Gallic acid as a standard to determine total phenol content Baking with conventional oven

o Biscuits CR-10 Colorimeter to measure color intensity Minolta Chromameter CR-300 to measure surface color Sensory analysis

o 10-member expert panel specialized in fat products for odor profiling of samples Volatile compound analysis using gas chromatography coupled with mass spectrometry Bovine myoglobin isolation and purification

o Ammonium sulfate precipitation and gel filtration chromatography Raw color analyses HunterLab MiniScan XE Plus spectrophotometer Meat pH using Polytron PT 10 homogenizer Water content using formulas Filtration through dry filter paper Mortar and pestle to grind sample Crystallization experiments – fast cooling rate High intensity ultrasound using Misonix S-3000 sonicator operating at acoustic frequency

20 kHz using 50W electrical power TA-XT plus Texture Analyzer

o Compression at 5 mm/s with strain of 25 percent o Compression at 5 mm/s with strain of 40 percent

SFC and droplet size distribution Microscopy using polarized light microscropy (PLM) to characterize morphology Burger patty basic formulation Stefan UMC 5 Electronic cutter


Derivatisation with dinitrophenylhydrazine (DNPH) for total protein carbonyl determination

Hobart Mixer, model H-600-D SafTest percent fat kit for total lipid content determination Aqualabs CX2 water activity meter SafTest Aldesafe test kit and Peroxysafe kit Irradiation

o Electron Paramagnetic Resonance Instrument Moiseeve and Cornforth to determine change of oxidation-reduction potential in meat Meat grinder – Model nr MG1532 Domestic microwave oven (Panasonic, 251 W Inverter) Microwave Workstation – computer interface, fiber optic slip ring for online temperature

measurements, the Workstation Commander Control, software for data collection DSC30 Differential Scanning Calorimeter Bruker Tesnor 27 Attentuated Total Freflectance-Fourier Transform Infrared operated by

OPUS software for determination of trans fat content using AOCS Official Method Pulsed nuclear magnetic resonance (NMR) spectrometer Rheological analysis using stress-controlled SR-5000 dynamic Stress Rheometer

3. What sensory measures were used in food evaluation? Evaluation of color Temperature Moisture content Color Texture analysis (hardness) Sensory analysis

o 10-member expert panel specialized in fat products for odor profiling of sampleso Three sessions – samples presented to panel members three times within eight

hourso Assessors passed basic odor test o Same panel used on a previous study on lipid oxidationo Trained in numerous sessions over several years in sensory analysis and on their

ability to evaluating using a control cardo Samples kept in 100-mL closed glass vessels at 35 degrees Celsius for 30 minutes

to allow for volatile compound release – then sniffed by panel memberso Glasses coded in random order o Six odor attributes offered for biscuit samples: brown (typical odor of burn grain,

chocolate, cocoa), sweet (associated with malthol or sugar-wool), fruity-floral (characteristic for trans-2-hexenal, malty (characteristic for malty extract), oxidized (characteristic for rancid fat or plant oils), overall acceptance (aroma of freshly baked biscuits)

o Odor attributes were chosen according to “Basic Flavor Descriptive Language” from Givaudan Roure Flavor Ltd.

o Panel members assigned intensity of each odor descriptor on a linear graphic scale from zero to 10


o Results from linear scales were converted into numerical values for data analysis (mean, variance, standard deviations)

4. Trends in ResearchMany of the experiments examining lipid content in food researched the effect of lipid

oxidation on the quality of the food. Lipid oxidation was a key factor needing to be controlled to enhance and maintain a quality product. For example, in the experiments examining lipid in California almonds and hulless barley kernels, storage time and temperature were key variables in determining the rate of lipid deterioration and its effect on the product (5). When replacing back-fat in porcine burger patties with vegetables oils, oxidative stability was a concern as well (8). Not only was it a concern in these experiments, it was a concern in most all experiments. Replacing lipids, such as trans fatty acids, with alternative oils was another trend that I felt was forming. With as many nutritional and health concerns as there are in regards to trans fatty acid consumption, this is a topic that I feel will be presenting much more research in the near future.

This led me to see another trend in the research: preventing this lipid oxidation. Methods of irradiation, replacement fats, interesterified fats with trans-free substrates and high intensity ultrasound waves were employed to try and reduce the opportunity for lipid rancidity. The effect of antioxidants on lipid stability was another method researched. The effect of green tea extracts on biscuit lipid fraction oxidation and antioxidants on salmon jerky were examined as having positive effects on maintaining lipid stability and product quality (3-9). All of the researchers also made sure to take note of color, texture or any other functional property change that may have been influenced by variables of the experiment.

5. Researchers’/My Suggestions for Further ResearchThe researchers are suggesting that further, more extensive experiments be done on the

functional properties of lipids to determine what can be done to prevent oxidation. This would improve store quality and storage time. Replacement of lipids with alternative oils is becoming an ever-popular trend that, as I mentioned previously, I believe is soon to become a very popular research subject. Determining oils, like the avocado oil that was used as a replacement for porcine back-fat, that can be substituted for lipid without affecting any structural, physical, or sensory qualities in a food could provide a new route for creating healthier foods that are normally saturated with unhealthy fats. They could also help enhance these functional properties, possibly providing for an even better product.

I also believe that future research should include more experiments testing the effectiveness of using power ultrasound to alter functional properties, in lipids and other compounds as well. By studying lipid crystallization under HIU, even more alternatives to fat use could be employed. This is also such an advanced form of technology that I believe more research should be done to quantify results and make them more reliable.

Research Form Questions

1. The research is presented in primarily past tense.

2. Some of the research presented was in active voice; some of the research was presented in passive voice.


3. If other research studies were discussed, it was primarily in the results and discussions section or in the methods and materials section. Many experiments referenced previously approved and generalized procedures and equations that were used. Other research studies were mentioned in the results and discussion session as a way of comparison. However, some experiments had very little data to refer to so the experiment was based solely on the data obtained.

4. Tables and figures were placed either in the methods and materials section or the results and discussion section. Tables in the methods and materials section were used to display variables, such as temperature, storage time, or altered ingredients, in a format that was easy to observe and compare before experimentation began. After the variables were identified in textual form, the table would follow in sequence. For tables and figures in the results and discussion session, this was not the case. Many times the discussion of variables would refer to a table or figure all located together in the middle or end of the section.


References

1. Hrynets, Y., Omana, D., Xu, Y., & Betti, M. (2011). Impact of citric acid and calcium ions on acid solubilization of mechanically separated turkey meat: Effect on lipid and pigment content. Poultry Science, 90(2), 458-466.

2. Liu, K., & Moreau, R. (2008). Concentrations of functional lipids in abraded fractions of hulless barley and effect of storage. Journal Of Food Science, 73(7), C569-C576.

3. Mildner-Szkudlarz, S., Zawirska-Wojtasiak, R., Obuchowski, W., & Gośliński, M. (2009). Evaluation of antioxidant activity of green tea extract and its effect on the biscuits lipid fraction oxidative stability. Journal Of Food Science, 74(8), 362-370.

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