Effect of sodium phytate, sodium pyrophosphate and sodium tripolyphosphate on physico-chemical characteristics of restructured beef

Modern Concepts of Restructured Meat Production and Market Opportunities

Restructured meat (RM) products are gaining importance as an essential component of the meat industry due to consumers' interest in health benefits. RM products imply the binding or holding of meat, meat by-products, and vegetable proteins together to form a meat product with meat's sensory and textural properties. RM products provide consumers with diversified preferences like the intake of low salt, low fat, antioxidants, and high dietary fiber in meat products. From the point of environmental sustainability, RM may aid in combining underutilized products and low-valued meat by adequately utilizing them instead of dumping them as waste material. RM processing technique might also help develop diversified and new hybrid meat products. It is crucial to have more knowledge on the quality issues, selection of binding agents, their optimum proportion, and finally, the ideal processing techniques. It is observed in this study that the most crucial feature of RM could be its healthy products with reduced fat content, which aligns with the preferences of health-conscious consumers who seek low-fat, low-salt, high-fiber options with minimal synthetic additives. This review briefly overviews RM and the factors affecting the quality and shelf life. Moreover, it discusses the recent studies on binding agents in processing RM products. Nonetheless, the recent advancements in processing and market scenarios have been summarized to better understand future research needs. The purpose of this review was to bring light to the ways of sustainable and economical food production.

Probing binding mode between sodium acid pyrophosphate and albumin: multi-spectroscopic and molecular docking analysis

Sodium acid pyrophosphate (SAPP) food additive is widely used as a preservative, bulking agent, chelating agent, emulsifier and pH regulator. It is also used as an improver of color and water retention capacity in the processing of various types of seafood, canned food, cooked meat and flour products. For the first time, we evaluated the SAPP interaction with bovine serum albumin (BSA) using spectroscopic methods including UV-Vis absorption, fluorescence spectroscopy, and surface plasmon resonance, and docking analysis to understand the mechanisms of complex formation and binding. The fluorescence intensity of BSA reduces when titrated with various concentrations of SAPP by forming a complex with BSA via a static quenching mechanism. The binding constant between BSA and SAPP decreased from 123,300 to 15,800 (M-1) with rising temperature, which indicates a decrement in complex formation owing to the interaction of SAPP with BSA. A negative ΔG° value means that SAPP binds spontaneously to BSA at all temperatures, and both ΔH° and ΔS° negative values indicate that hydrogen bonds (H-bonding) and van der Waals forces are the primary forces involved in the binding processes. The UV-Vis spectrum of BSA reduced upon increasing SAPP concentrations due to forming a new ground state complex between SAPP and BSA. Molecular docking study shows that residues Arg256, Ser259, Ser286, Ile 289 and Ala 290 play an important role in SAPP binding process to site I (subdomain IIA) of BSA through H-bonding and van der Waals forces, which is supported by the thermodynamic study.Communicated by Ramaswamy H. Sarma.

Applications of Plant Bioactive Compounds as Replacers of Synthetic Additives in the Food Industry

According to the Codex Alimentarius, a food additive is any substance that is incorporated into a food solely for technological or organoleptic purposes during the production of that food. Food additives can be of synthetic or natural origin. Several scientific evidence (in vitro studies and epidemiological studies like the controversial Southampton study published in 2007) have pointed out that several synthetic additives may lead to health issues for consumers. In that sense, the actual consumer searches for "Clean Label" foods with ingredient lists clean of coded additives, which are rejected by the actual consumer, highlighting the need to distinguish synthetic and natural codded additives from the ingredient lists. However, this natural approach must focus on an integrated vision of the replacement of chemical substances from the food ingredients, food contact materials (packaging), and their application on the final product. Hence, natural plant alternatives are hereby presented, analyzing their potential success in replacing common synthetic emulsifiers, colorants, flavorings, inhibitors of quality-degrading enzymes, antimicrobials, and antioxidants. In addition, the need for a complete absence of chemical additive migration to the food is approached through the use of plant-origin bioactive compounds (e.g., plant essential oils) incorporated in active packaging.

Effects of sodium chloride and sodium tripolyphosphate on the prooxidant properties of hemoglobin in washed turkey muscle system

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MetHb in WTM acted as the most effective pro-oxidant, followed by hemin and oxyHb.

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The addition of NaCl significantly increased the oxyHb-mediated lipid oxidation.

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STPP inhibited oxyHb-mediated lipid oxidation.

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Formation of metHb and pH paly critical roles in oxyHb-mediated lipid oxidation.

This study examined the effects of sodium chloride (NaCl) and sodium tripolyphosphate (STPP) on lipid oxidation induced by oxyhemoglobin (oxyHb) in washed turkey muscle (WTM) model. To explore the reasons for observed effects, the pro-oxidant abilities of Hb derivatives (e.g., metHb, oxyHb, hemin, Fe²⁺, and Fe³⁺), pH change, and antioxidation of Hb in the presence of NaCl or STPP were also analyzed. The observed lipid oxidation capacity in WTM followed the order metHb > hemin > oxyHb > Fe²⁺ > Fe³⁺. Added Fe²⁺ accelerated auto-oxidation of oxyHb and oxyHb-mediated lipid oxidation. Hb auto-oxidation to metHb increased as the pH decreased from 6.6 to 5.0. NaCl promoted oxyHb-mediated lipid oxidation due to NaCl causing decreased pH value and increased formation of metHb. STPP inhibited oxyHb-mediated lipid oxidation and weakened the pro-oxidative effect of NaCl. This could be attributed to STPP increasing the pH, inactivating free iron, and inhibiting formation of metHb.

Replacement of Sodium Tripolyphosphate with Iota Carrageenan in the Formulation of Restructured Ostrich Ham

The influence of iota carrageenan (iota-CGN) as a partial replacement of sodium tripolyphosphate (STPP) was investigated on the physical (pH, yield, instrumental color, texture profile analysis), chemical (moisture, protein, total fat, ash, phosphate) and sensory (descriptive analysis, acceptance testing) quality of restructured ostrich ham (95% lean meat plus fat). Treatments consisted of five decreasing levels of STPP (0.70%, 0.53%, 0.35%, 0.18% and 0%) that were simultaneously substituted with five increasing levels of iota-CGN (0%, 0.1%, 0.2%, 0.3% and 0.4%). Cooked yield, hardness, cohesiveness, and gumminess of restructured ostrich ham increased (p ≤ 0.05) with decreasing levels of STPP (and increased levels of iota-CGN). No significant trend in instrumental color measurements or springiness were observed between treatments. Ostrich ham with 0.35% STPP and lower had increased ostrich meat aroma and flavor, while spicy aroma and flavor, mealiness and consumer acceptance decreased. Iota carrageenan can be substituted for STPP (up to 0.35% STPP and 0.2% iota-CGN) to produce reduced STPP ham.

Influences of encapsulated polyphosphate incorporation on oxidative stability and quality characteristics of ready to eat beef Döner kebab during storage

The effect of different polyphosphates (sodium tripolyphosphate, STP; sodium hexametaphosphate, HMP; sodium pyrophosphate, SPP) and ratios of unencapsulated (u) and encapsulated (e) forms of these polyphosphates (PP, 0.5%) on lipid oxidation inhibition and quality characteristics of ground beef döner kebab were evaluated. STP usage provided lower cooking loss (CL) than HMP or SPP (P < .05). Döners containing STP had higher pH than those with HMP or SPP (P < .05). Regardless of ePP ratio in the total added PP (0.5%), added ePP created the same effect on CL and pH as 0.5% uPP in döner samples. The highest orthophosphate (OP) was obtained with STP, followed by SPP, HMP and control (no PP; P < .05). OP values generally decreased with increasing ePP ratio up to 0.4% in the total added PP (P < .05). Thiobarbituric acid reactive substances (TBARS) and lipid hydroperoxide (LPO) in döners containing PP were lower than control (P < .05). The lowest TBARS and LPO were determined in döners containing STP or SPP (P < .05). In general, increasing ePP ratio (up to 0.2% for STP and SPP, and 0.4% for HMP) in the total added PP provided further reduction in TBARS and LPO (P < .05). TBARS and LPO results suggested that ePP incorporation may be strategic implementation for meat industry to control lipid oxidation in ready to eat döner kebab.

Effects of partial and complete replacement of added phosphates with encapsulated phosphates on lipid oxidation inhibition in cooked ground meat during storage

The objective of this research was to investigate the influence of various levels (0.0, 0.1, 0.2, 0.3, 0.4, 0.5%) of added encapsulated polyphosphates (sodium tripolyphosphate; sodium pyrophosphate) combined with unencapsulated polyphosphate to total 0.5% on the inhibition of lipid oxidation in cooked ground meat (beef, chicken) during refrigerated storage (0, 1, 7 d). The use of sodium tripolyphosphate (encapsulated sodium tripolyphosphate, unencapsulated sodium tripolyphosphate) led to lower cooking loss compared to sodium pyrophosphate in both meat species (p < 0.05). Increasing encapsulated sodium tripolyphosphate up to 0.3% decreased cooking loss in ground beef (p < 0.05). Added encapsulated polyphosphate at 0.5% had the same effect on pH as 0.5% unencapsulated polyphosphate in the cooked ground beef and chicken. A higher accumulation of orthophosphate was determined in the samples with sodium tripolyphosphate compared to those with sodium pyrophosphate (p < 0.05). Inclusion of a minimum of 0.1% encapsulated polyphosphate decreased thiobarbituric acid reactive substances and lipid hydroperoxides on 7 d. Increasing encapsulated sodium tripolyphosphate and encapsulated sodium pyrophosphate up to 0.2% in beef decreased thiobarbituric acid reactive substances at 7 d. Addition of 0.4% encapsulated sodium tripolyphosphate and 0.3% encapsulated sodium pyrophosphate in chicken prevented any increase in TBARS during storage. Incorporating encapsulated sodium pyrophosphate at 0.3% inhibited lipid hydroperoxide formation in beef and chicken. The meat industry could achieve enhanced lipid oxidation inhibition by replacing some of the unencapsulated polyphosphate with encapsulated polyphosphate in their product formulations.

The role of phosphate-containing medications and low dietary phosphorus-protein ratio in reducing intestinal phosphorus load in patients with chronic kidney disease

Chronic kidney disease-mineral and bone disorder (CKD-MBD) is a common complication in patients experiencing end-stage renal disease (ESRD). It includes abnormalities in bone and mineral metabolism and vascular calcification. Hyperphosphatemia is a major risk factor leading to morbidity and mortality in patients with chronic kidney disease. Increased mortality has been observed in patients with ESRD, with serum phosphorus levels of >5.5 mg/dL. Therefore, control of hyperphosphatemia is a major therapeutic goal in the prevention and treatment of CKD-MBD. The treatment of hyperphosphatemia includes decreasing intestinal phosphorus load and increasing renal phosphorus removal. Decreasing the intestinal load of phosphorus plays a major role in the prevention and treatment of CKD-MBD. Among the dietary sources of phosphorus, some of the commonly prescribed medications have also been reported to contain phosphorus. However, drugs are often ignored even though they act as a potential source of phosphorus. Similarly, although proteins are the major source of dietary phosphorus, reducing protein intake can increase mortality in patients with CKD. Recently, the importance of phosphorus/protein ratio in food have been reported to be a sensitive marker for controlling dietary intake of phosphorus. This review summarizes the progress in the research on phosphate content in drugs as an excipient and the various aspects of dietary management of hyperphosphatemia in patients with CKD, with special emphasis on dietary restriction of phosphorus with low dietary phosphate/protein ratio.

Quality Characteristics of Low-salt Chicken Sausage Supplemented with a Winter Mushroom Powder

Chicken meat is a low-fat and high-protein food and consumption of chicken meat has been increasing globally. Various food ingredients are widely added for their specific purpose to processed chicken meat. Nonetheless, concerns about the association between high sodium intake and various diseases as well as negative perceptions of artificial additives are increasing. Therefore, in meat products, it is necessary to reduce the amount of salt and to replace artificial additives with natural ingredients. Our aim was to investigate the quality characteristics of low-salt chicken sausages manufactured with the addition of a winter mushroom powder. Sausages was manufactured with sodium pyrophosphate (0.3%) or winter mushroom powder (0%, 0.5% and 1.0%) to ground chicken breast. As a result of addition of the winter mushroom powder to low-salt chicken sausages, pH of the meat batter increased, and the proportion of jelly and melted fat exuded from sausages was reduced. The texture of sausages was softened and lipid oxidation in sausages was inhibited by the winter mushroom powder. This powder did not negatively affect the color and sensory properties of the sausages. According to the results of this study, the winter mushroom powder can serve as a natural ingredient to improve quality of low-salt chicken sausages.

Phosphate Reduction in Emulsified Meat Products: Impact of Phosphate Type and Dosage on Quality Characteristics

Phosphate reduction is of important industrial relevance in the manufacturing of emulsified meat products because it may give rise to a healthier product. The effect of seven different phosphate types was tested on the physicochemical and quality characteristics to select the most promising phosphate type for further cooked sausage manufacturing. Next, phosphate mass fraction was gradually reduced. Tetrasodium di- or pyrophosphate (TSPP) and sodium tripolyphosphate (STPP) increased pH, reduced structural properties, resulted in the highest emulsion stability, lowest cooking loss and had little effect on hardness. Based on the viscoelastic properties, a minimum mass fraction of 0.06% TSPP was sufficient to obtain an acceptable quality product. Rheology proved to be a very useful tool to evaluate the quality of meat products, as it gives insight in the structure of the meat product and especially the functional properties of meat proteins. Based on the obtained results, it can be concluded that the current amount of phosphate added to emulsified meat products can be significantly reduced with minimal loss of product quality.

The effects of potato and rice starch as substitutes for phosphate in and degree of comminution on the technological, instrumental and sensory characteristics of restructured ham

The effects of sodium tripolyphosphate (STPP), two sources of starch (potato starch: PS and rice starch: RS) and comminution degree (CD) on the technological, instrumental and sensory characteristics of reformed hams were studied using response surface methodology. Both starches reduced cook loss and decreased ham flavour intensity, but RS had stronger effects on instrumental measures of texture, while PS was associated with improved juiciness when low/no added STPP was included. Coarsely ground meat, processed 100% with the kidney plate was associated with slightly increased cook loss, reduced texture profile analysis parameters and a more intense ham flavour compared to the other treatment (80% ground with a kidney plate plus 20% with a 9mm plate). STPP was the sole factor affecting overall liking. If starch is included in the formulation, the standard level of STPP (0.3%) can be reduced by half with no increase in cook losses, but some decline in sensory quality cannot be avoided.

Impact of Added Encapsulated Phosphate Level on Lipid Oxidation Inhibition during the Storage of Cooked Ground Meat

The effect of levels (0.1%, 0.2%, 0.3%, 0.4%, 0.5%) of added encapsulated (e) phosphate (sodium tripolyphosphate, STP; sodium hexametaphosphate, HMP; sodium pyrophosphate, SPP) on lipid oxidation inhibition during storage (0, 1, and 7 d) of ground meat (chicken, beef) was evaluated. The use of eSTP and eSPP resulted in lower and higher cooking loss (CL) compared to eHMP, respectively (P < 0.05). Increasing encapsulated phosphate level (PL) enhanced the impact of phosphates on CL in both chicken and beef samples (P < 0.05). Encapsulated STP increased pH, whereas eSPP decreased pH (P < 0.05). pH was not affected by PL. The highest orthophosphate (OP) was obtained with eSTP, followed by eSPP and eHMP (P < 0.05). The level of OP determined in both chicken and beef samples increased (P < 0.05) during storage. Increasing PL caused an increase in OP (P < 0.05). The highest reduction rate in the formation of thiobarbituric acid reactive substances (TBARS) and LPO for both meat species were obtained with eSPP, followed by eSTP and eHMP (P < 0.05). Increasing PL resulted in lower TBARS and LPO (P < 0.05). Findings suggest that encapsulated phosphates can be a strategy to inhibit lipid oxidation for the meat industry and the efficiency of encapsulated phosphates on lipid oxidation inhibition can be enhanced by increasing PL.

Effects of Different End-Point Cooking Temperatures on the Efficiency of Encapsulated Phosphates on Lipid Oxidation Inhibition in Ground Meat

Effects of 0.5% encapsulated (e) phosphates (sodium tripolyphosphate, STP; sodium hexametaphosphate, HMP; sodium pyrophosphate, SPP) on lipid oxidation during storage (0, 1, and 7 d) of ground meat (chicken, beef) after being cooked to 3 end-point cooking temperatures (EPCT; 71, 74, and 77 °C) were evaluated. The use of STP or eSTP resulted in lower (P < 0.05) cooking loss (CL) compared to encapsulated or unencapsulated forms of HMP and SPP. Increasing EPCT led to a significant increase in CL (P < 0.05). Both STP and eSTP increased pH, whereas SPP and eSPP decreased pH (P < 0.05). The higher orthophosphate (OP) was obtained with STP or SPP compared to their encapsulated counterparts (P < 0.05). The lowest OP was determined in samples with HMP or eHMP (P < 0.05). A 77 °C EPCT resulted in lower OP in chicken compared to 74 and 71 °C (P < 0.05), dissimilar to beef, where EPCT did not affect OP. In encapsulated or unencapsulated form, using STP and SPP enhanced reduction in TBARS and lipid hydroperoxides (LPO) compared with HMP (P < 0.05). Regardless of the phosphate type, more effective lipid oxidation inhibition was achieved by the use of encapsulated forms (P < 0.05). Increasing EPCT resulted in lower TBARS in beef and higher LPO values in both beef and chicken samples (P < 0.05). Findings suggest that encapsulated phosphates can be a strategy to inhibit lipid oxidation for meat industry and the efficiency of encapsulated phosphates on lipid oxidation inhibition can be enhanced by lowering EPCT.

Development and analytical evaluation of a spectrophotometric procedure for the quantification of different types of phosphorus in meat products

Phosphorus is an important natural nutrient, but high dietary phosphorus intake, including that sourced from added preservatives, is of great concern in renal patients. In this context a reliable analytical method able to quantify differential phosphorus in food could be a valuable tool for monitoring diet composition This paper presents a novel analytical procedure to quantify the following kinds of phosphorus in cooked ham: total (TP), inorganic (IP), from phospholipids (PL), and from phosphoproteins (PP). This technique is based on a suitable sample preparation followed by spectrophotometric analyses. Analytical performances of each method were evaluated, taking advantage also of food industry certified material and in-house reference samples. Limit of detection and limit of quantification values for TP, IP, PP-derived, and PL-derived phosphorus were 13 and 37, 11 and 33, 2 and 20, and 6 and 16 mg P/100 g fresh mass, respectively. Similar results were obtained when this procedure was used to quantify different types of phosphorus present in cooked ham samples. In conclusion, this procedure is effective for quantifying the content of different types of phosphorus present in cooked ham, which can be contributed by different phosphorus-containing ingredients and additives. To the best of the authors' knowledge, this is the first time that simultaneous determination of TP, IP, PL, and PP in cooked ham has been reported.

Physicochemical and sensory characteristics of restructured beef steak with added walnuts

The effects of different proportions (0, 5, 10, 15%) of added walnuts on the physicochemical and sensory characteristics of restructured beef steak were evaluated. The addition of 10 and 15% walnut reduced (P<0.05) cooking loss. Increasing proportions of walnut in the beef steak increased (P<0.05) water binding and reduced (P<0.05) fat binding properties. The addition of walnut did not affect (P>0.05) textural properties in uncooked restructured beef steak, but in cooked products Kramer shear force and bind strength were reduced (P<0.05) when 10% or more of walnut was added. Product morphology characteristics suggest that walnut interferes with the formation of protein network structures. Restructured steaks made with added walnut presented acceptable sensory properties. Incorporation of nuts in meat products can be use to confer potential heart-healthy benefits (Spanish Patent Application 200300367).

Irradiation and additive combinations on the pathogen reduction and quality of poultry meat

Reduction of foodborne illnesses and deaths by improving the safety of poultry products is one of the priority areas in the United States, and developing and implementing effective food processing technologies can be very effective to accomplish that goal. Irradiation is an effective processing technology for eliminating pathogens in poultry meat. Addition of antimicrobial agents during processing can be another approach to control pathogens in poultry products. However, the adoption of irradiation technology by the meat industry is limited because of quality and health concerns about irradiated meat products. Irradiation produces a characteristic aroma as well as alters meat flavor and color that significantly affect consumer acceptance. The generation of a pink color in cooked poultry and off-odor in poultry by irradiation is a critical issue because consumers associate the presence of a pink color in cooked poultry breast meat as contaminated or undercooked, and off-odor in raw meat and off-flavor in cooked meat with undesirable chemical reactions. As a result, the meat industry has difficulties in using irradiation to achieve its food safety benefits. Antimicrobials such as sodium lactate, sodium diacetate, and potassium benzoate are extensively used to extend the shelf-life and ensure the safety of meat products. However, the use of these antimicrobial agents alone cannot guarantee the safety of poultry products. It is known that some of the herbs, spices, and antimicrobials commonly used in meat processing can have synergistic effects with irradiation in controlling pathogens in meat. Also, the addition of spices or herbs in irradiated meat improves the quality of irradiated poultry by reducing lipid oxidation and production of off-odor volatiles or masking off-flavor. Therefore, combinations of irradiation with these additives can accomplish better pathogen reduction in meat products than using them alone even at lower levels of antimicrobials/herbs and irradiation doses. Effects of irradiation and additive combinations on the pathogen reduction and quality of poultry meat will be discussed in detail.

The effects of tumbling and sodium tripolyphosphate on the proteins of döner

This study was designed to investigate the influence of tumbling and sodium tripolyphosphate (STPP) with marination on the protein structure of raw and cooked döner, a traditional Middle East product consumed widely in many areas of the world. Proximate composition (%moisture, %protein, %fat, %ash, and pH value), salt soluble protein (SSP) and total α-amino grup amount were determined. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was used to investigate alterations in the sarcoplasmic and myofibrillar proteins. Utilization of STPP increased the moisture content and ash contents, and pH value of raw döner (p<0.05). Only tumbling and STPP had a significant two-way interaction for moisture content, SSP and total α-amino group amounts of cooked döner (p<0.05). None of the treatments significantly affected the fraction of sarcoplasmic and myofibrillar proteins. In addition, cooking caused proteolysis of these proteins.

Phosphate additives determination in meat products by 31-phosphorus nuclear magnetic resonance using new internal reference standard: hexamethylphosphoroamide

New (31)P NMR internal reference standard - hexamethylphosphoroamide (HMPA) was applied for determination of added polyphosphates and their ionic forms in raw pork meat and meat products. Phosphate species were determined after extraction with a boric acid buffer (pH=9) and EDTA solution, using internal standard (HMPA) procedure. Hexamethylphosophoroamide was also used as the NMR reference standard. Linear correlations between phosphates and polyphosphate concentrations and (31)P NMR signal areas were found in the range 81-5236 mg P/dm(3), presenting 95-99% recovery and variation coefficient (CV) ≤ 5%. Studied HMPA procedure revealed shorter analysis time and the same recovery (>95%) and precision (CV=1.3-2.7%) in comparison to MDPA method. Results of phosphate determination by both (31)P NMR methods were tested against the molybdenumvanadate yellow spectrophotometric method (standard PN-ISO 13730, 1999) using standard reference material (certified phosphate solution).

Comparison of spice-derived antioxidants and metal chelators on fresh beef color stability

Effects of Type I antioxidants eugenol and rosmarinic acid were compared to those of Type II antioxidants milk mineral (MM), sodium tripolyphosphpate (STPP), and phytate in raw ground beef held for 14 days at 4 degrees C in oxygen-permeable polyvinylchloride. Meat color stability was measured as % oxymyoglobin, Hunter a * value, chroma, and hue angle. Significant correlations (P<0.0001) were observed between all color measurement methods. By day 14, STPP-treated patties lost more red color (P<0.05 for a* and hue angle) and had higher thiobarbituric acid values than other treatments. By day 14, MM was as effective as eugenol and rosmarinate at preventing oxymyoglobin oxidation (72, 76, and 71% retained, respectively) and red color loss as measured by a * (9.2, 9.4, and 10.9), hue angle (58.4, 56.2, and 53.5), and chroma (17, 17, and 18), but was unable to inhibit microbial growth as effectively as the spice-derived antioxidants.

Effect of phosphate treatments on microbiological, physicochemical changes of spent hen muscle marinated with Tom Yum paste during chilled storage

BACKGROUND

This research aimed to study the effect of phosphate on quality of ready-to-cook spent hen muscle marinated with Tom Yum paste, a famous Thai food made from chilli, lime leaves and garcinia (pH 2.5-2.9). The effects of phosphate treatments (phosphate types, soaking time, and phosphate concentration) on physical characteristics of spent hen muscle in high acid condition were investigated. Quality changes of muscles pretreated with or without phosphate and marinated with Tom Yum paste were determined during storage at 4 degrees C for 30 days.

RESULTS

The acidified muscle pretreated with 40 g L(-1) sodium tripolyphosphate for 10 h had the highest marinade absorption, and the lowest cooking loss and shear force among all treatment samples. Microstructures of acidified muscle pretreated with and without sodium tripolyphosphate showed significant swelling with larger fibre diameter. Phosphate pretreatment had no influence on cooking loss, shear force and thiobarbituric acid reactive substance values of Tom Yum marinated muscle during storage. Tom Yum marination with phosphate pretreatment caused a higher increase in psychrophilic bacteria compared to that of marinating without phosphate.

CONCLUSION

Phosphate pretreatment could not improve the physical quality of Tom-Yum marinated spent hen muscle and affected the antimicrobial property of Tom-Yum marinade, resulting in a reduction of shelf-life of the marinated muscle from 30 days to 20 days.

Effect of chelating agents and spice-derived antioxidants on myoglobin oxidation in a lipid-free model system

This study compared myoglobin (Mb) oxidation in lipid-free model systems containing iron and Type I (radical quenching) or Type II (metal chelating) antioxidants. Oxidation was measured as loss of oxymyoglobin (MbO(2)) during 0 to 24 h holding at 22 degrees C. Sodium tripolyphosphate (STPP) demonstrated iron-binding ability at all concentrations tested (88% and 21% added iron bound at 1 and 0.05 mg/mL, respectively). Iron chelation was observed for phytic acid only at the highest concentration (9.5% bound at 1 mg/mL phytate). Neither Type I antioxidant (rosmarinate or eugenol) demonstrated any iron chelating ability (<0.5% bound). In presence of iron, Type I antioxidants had a significant (P < 0.05) prooxidant effect (54.7% retention of MbO(2) in control, 9.5% and 37.5% retention in rosmarinate and eugenol samples, respectively). The Type II antioxidants (STPP and phytate) were more effective inhibitors (P < 0.05) of Mb oxidation than Type I antioxidants, (68.7% and 61.1% for STPP and phytate, respectively). Type I antioxidants were capable of rapid reduction of ferric iron to the ferrous form, as measured by the ferrozine assay. This strong reducing ability accounted for the prooxidant effects of rosmarinic acid and eugenol, since ferrous iron is the form associated with generation of oxygen radicals, and subsequent Mb oxidation. Type II antioxidants chelated and thus prevented the oxidizing effect of added ferrous iron. Mb oxidation can proceed rapidly (within 15 min) in the presence of iron and the absence of lipid, especially if reducing compounds such as rosmarinic acid or eugenol are also present to maintain iron in an active ferrous form.

Characteristics of restructured beef steak with different proportions of walnut during frozen storage

Physicochemical (thawing loss, cooking loss, surface shrinkage, texture, colour and lipid oxidation) and sensory properties of restructured beef steak with different levels of added walnut (0%, 10% and 20%) were determined at various times during frozen storage up to 128 days. Cooking loss (CL), Kramer shear force (KSF) and binding strength (BS) of restructured beef decreased (P<0.05) as the proportion of walnut increased. Walnut enhanced (P<0.05) lightness and yellowness and reduced (P<0.05) redness. Frozen storage did not affect (P>0.05) CL, KSF and BS of restructured beef steak. Redness decreased (P<0.05) over storage for all samples. Lipid oxidation of restructured beef steak containing walnut was not a limiting factor for frozen stability of meat products. Frozen storage had no effect (P>0.05) on the sensory quality of restructured beef steak.