Progress 10/01/12 to 09/30/13
Outputs
Target Audience:
Nothing Reported
Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? This research provided the opportunity for a Masters candidate to learn numerous chemical and physical methods associated with assessing meat quality. These will be very valuable skills as the student enters the food industry. The methods included: proximate analysis (ash, fat, moisture), pH, soluble ortho-phosphate analysis, and two measures of lipid oxidation (thiobarbituric acid-reactive substances, TBARS; peroxides value analysis). Of particular value was the experience the student gained from working out a successful soluble ortho-phosphate analysis for this project. Published procedures were rather vague and flawed. As part of a non-formal collaborative arrangement the student got to work side by side with a visiting scientist from Turkey. Together they worked out a procedure that is now used in my lab and the visiting scientist’s lab back in Turkey. The student also learned about different statistical analysis designs and interpretation of results. Besides these methodologies the student gain experience associated with the operation of various meat processing equipment (choppers, mixes, meat packaging systems). The student was also able to attend a national meeting organized by the American Meat Science Association. Attending this meeting provided the opportunity for this student to be exposed to current topics in meat science research and to interact with professionals and students from around the U.S. How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Impact- As refrigerated processed meats are stored lipids in the product become oxidized. This condition can cause consumer dissatisfaction and shorten shelf life. From a health standpoint oxidized lipids are undesirable as they can induce changes in physiologically desirable bioactive compounds. Therefore, controlling lipid oxidation has positive implications associated with food quality and human health. This research clearly established the ability of the turkey industry to greatly reduce the development of lipid oxidation. Broadly this research also has positive implications for controlling lipid oxidation in a variety of other muscle foods (e.g. red meat, chicken, seafood). This research established a practical way to limit oxidation by basically preserving the antioxidant ability of commercially used phosphates. Simply encapsulating (coating) the phosphates with a hydrogenated vegetable oil provided far greater control of lipid oxidation than the common practice of just adding unencapsulated phosphate. It is worth mentioning that encapsulation of food ingredients is a common, commercially available process. Depending upon the phosphate selected the improvement was up to 14 times more effective. Two of the encapsulated (encap) phosphates limited oxidation on product stored 7 days to a level less than the turkey containing the counterpart unencapsulated (unencap) phosphates only stored for 1 day. All three experimental objectives were completed. Pertinent interactions among the main effects as indicated in the third objective are discussed within the first two objectives. Objective 1. Determine the effect of meat pH on encapsulated polyphosphate control of lipid oxidation. Design- The experiment used boneless turkey breasts (1 day postmortem). Turkey was collected into two different pH groups with a minimum difference between each group of 0.2 pH units. Ground turkey was mixed with one of the test phosphates (0.4% meat weight basis, mwb), water (10% mwb), and salt (1% mwb). Phosphate types included: sodium tripolyphosphate (STP), sodium hexametaphosphate (HMP) and sodium pyrophosphate (SPP). Phosphates were tested unencapsulated and encapsulated (encapsulated to release at 140 F: HMP140, SPP140, STP140; encapsulated to release at 155 F: HMP155, SPP155, STP155). With the nonmeat ingredients incorporated, the raw sample was stuffed into plastic casings and water cooked (end point temperatures, EPT; 165 F, 175 F) after they reached 3, 6, 24 hr of pre-cook storage time (35 F). Chilled sample links were ground, overwrapped in an oxygen permeable film, and stored (post-cook storage, 0, 1, 7 days; 35 F). This experiment enable the determination of six main effects which included: pH group (low, high), phosphate type, precook storage, phosphate release (unencapsulated: immediate; encapsulated: 140 F or 155 F), EPT, and post-cooked storage. Samples were analyzed for pH, soluble orthophosphate (indication of phosphate breakdown, SOP), lipid oxidation (thiobarbituric acid-reactive substances, TBARS; lipid peroxides, LP), and cooking loss. Results- In the uncooked samples, unencapsulated phosphates developed higher amounts of soluble orthophosphate (6172 ug/g) than their encapsulated counterparts indicating the encapsulation (5573 ug/g) did indeed protect the polyphosphate from hydrolysis by endogenous enzymes (phosphatases). A minor difference between the two turkey pH groups remained in the cooked samples for two of the phosphates used (SPP, 5.90 versus 5.96; STP, 6.28 versus 6.31). Phosphate type had an interaction with phosphate release (immediate, 140, 150 F) for SOP (ug/g) in raw samples. HMP had the lowest values (4690, 4548, 4510; respectively). This suggests HMP may not be as susceptible to phosphatase hydrolysis as the other phosphates. Unencapsulated SPP and STP had the two highest SOP values (7000, 6826). For SPP no difference was found between 140 F (5752) and 155 F (5757). However for STP, 154 F (6606) had higher SOP than 140 F (6268). Pre-cook storage time (3, 6, 24 hr) had no influence on SOP (5876, 5753, 5688 μg/g SOP, respectively) in the raw samples. It is likely that all of the unencapsulated phosphates were hydrolyzed within 3 hr after incorporation and the encapsulated phosphates remained protected from hydrolysis. In the cooked samples, precooked storage time (3, 6, 24 hr) also did not affect SOP (5737, 5755, 5827 μg/g, respectively) or LP (741, 730, 745 μg/g, respectively). However for TBARS, 24 hr storage resulted in a lower value (0.52 mg/kg) than either 3 or 6 hr (0.55, 0.56, respectively). Such a difference is unlikely to represent a detectable human sensory response. Phosphate type, phosphate release, and post-cooked storage time interacted to have an effect on TBARS and LP. However as expected the consistent trend was TBARS increased with post-cooked storage time for both these measures of lipid oxidation. Unencapsulated phosphates always had higher values for TBARS than the encapsulated phosphates (140, 155 F). The TBARS for the 155 F group were either equal to or lower than the 140 F group. On day 7 the encapsulated phosphates (HMP155, SPP155, and STP155) had lower (1.5, 5, and 3.6 times lower) TBARS than the corresponding unencapsulated phosphates. To demonstrate the effectiveness of encapsulation, on day 7 the TBARS value of HMP155 was as low as the unencapsulated day 1 sample. Both SPP155 and SPP140 on day 7 were lower than unencapsulated SPP day 0 sample. The same was true for the encapsulated STP. On day 7 the encapsulated phosphates (HMP155, SPP155, and STP155) had lower (2.6, 14.7, and 6.5 times lower) LP than the corresponding unencapsulated phosphates. Melting point of the coating did not appear to have a significant effect on SOP. Encapsulation was not expected to affect the pH as the encapsulated phosphates were designed to be fully released upon cooking. The results indicated the encapsulated phosphates had statistically equal to (7.0%, 155 F) or slightly higher (7.4%) cooking loss than unencapsulated phosphates (6.5%). Objective 2. Determine the effect of meat age on encapsulated polyphosphate control of lipid oxidation. Design- A replicated experiment was conducted using turkey breast meat stored postmortem (2, 4 days) before use. Similar product manufacturing was used to test the same independent variables as in experiment 1 except the pH group treatment was replaced by turkey meat age (2, 4 days). Results- Samples produced from older meat (4 day) and with a pre-cooked storage of 6 or 24 hours resulted in the two highest SOP values in the uncooked product. SOP on uncooked product from 2 day aged meat had similar SOP values regardless of the pre-cooked storage time. For the day 4 aged meat the SOP values were higher for the 6 hr precooked stored group than the 3 hr group. Cooked product from 4 day aged meat was equal to the 2 day aged meat in SOP on day 7 of storage for HMP (4782 versus 4644 ug/g) and SPP (5572 versus 5480 ug/g). However, SOP was higher in the older meat (6842 versus 6501 ug/g) for STP. In general TBARS were lower in less aged turkey meat (0.44 versus 0.52 mg/kg). This pattern remained valid regardless of the phosphate release point (immediate, 140 F, 155 F). Use of the encapsulated phosphates on fresh 2 day aged meat and stored prior to heat processing (3, 6, 24 hr) reduced TBARS 2.8, 2.9, and 3.6 times more than non-encapsulated phosphate treatments (0.73, 0.77, 0.78 mg/kg; respectively). Conclusions: Although turkey meat pH grouping and meat age affected some of the physical and chemical properties associated with lipid oxidation, there were limited and often weak interactions involving these two main effects with other test factors. However, encapsulated phosphates performed well in controlling lipid oxidation in either pH group or meat age providing the opportunity for turkey meat processors to improve the quality of uncured processed meats made with turkey.
Publications
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Progress 01/01/12 to 12/31/12
Outputs
OUTPUTS: This effort is centered on demonstrating the ability to preserve the strong antioxidant capabilities of polyphosphates by protecting them from enzymes naturally found in meat (phosphatases). The enzymes hydrolyze the polyphosphates which greatly reduces their antioxidant properties. The approache used to protect the polyphosphates involved coating (encapsulating) them with a hydrogenated vegetable oil which is a solid at refrigerated temperatures. Upon cooking the meat containing the encapsulated phosphates, the coating melts causing their release after heat inactivation of the polyphosphatases. The three phosphates that have been encapsulated include: sodium tripolyphosphate (STP; Brifisol 5-1327, BK Giulini), sodium hexameta phosphate (HMP; 7-1462 BK Giulini) and sodium acid pyrophosphate (SPP; 5-1230, BK Giulini). Phosphates were encapsulated to provide two different melting release points (60 C, 140 F; 68 C, 154 F). Two commercially available hydrogenated vegetable oils (Loders Croklaan, Channahon, IL) were selected to achieve these temperature release points. The two hydrogenated vegetable oils were a hydrogenated palm oil (27 Stearine) with a capillary melting point of 60C (140F) and hydrogenated soybean oil (17 Stearine) with a capillary melting point of 68C (154F). A method of determining orthophosphates was developed. In addition, three preliminary trials were completed to develop an appropriate thermal processing schedule for the ground turkey model system used to evaluate the efficacy of the encapsulated phosphates. PARTICIPANTS: Chen Du, a graduate student, worked on this project. Dr. Birol Kilic (Suleyman Demirel Universitesi, Isparta, Turkey) was a visiting scientist. He helped develop the orthophosphate method and provided methods development training to Chen Du. BK Giulini company also contributed to this project. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: For the higher endpoint temperature release coating, a hydrogenated soybean oil that was used had a melting point one degree lower than initially proposed. Nevertheless, this one was selected because it was commercially available and acceptable for the experimental objective of determining if a higher endpoint temperature release point would be beneficial to preserving the antioxidant capabilities of the polyphosphates. The proposed orthophosphate procedure (Molins et al., 1985) required a chemical that is no longer readily available in the U.S. and required use of a relatively toxic chemical. The new method developed utilizes safer reagents that are readily available. The original research was designed to thermal process the ground turkey meat mixes in plastic centrifuge tubes. It was determined that cooking the tubes in a preheated waterbath resulted in too short of a transition time between the two temperature release endpoints. In addition, the thermal processing profile was dramatically different than a typical processing profile used in a commercial processing plant. Instead of filling centrifuge tubes with the test meat mixes, based on preliminary results, somewhat larger test batches will be made and stuffed into actual fibrous sausage casings and thermally processed in a smokehouse. By making this change, a more valuable assessment of the efficacy of the encapsulated phosphates can be made.
Impacts
A collaborative arrangement was established with Dr. Birol Kilic (Suleyman Demirel Universitesi, Isparta, Turkey). Dr. Kilic secured the funding necessary to encapsulate the polyphosphates. In addition, while he was a visiting scientist, a method was developed for determining orthophosphates. This was a valuable effort because it will be used for this Hatch project and to enable direct comparative evaluation of results from our studies with the same encapsulated phosphates.
Publications
- No publications reported this period
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