Evaluation of sodium lactate as a replacement for conventional chemical preservatives in comminuted sausages inoculated with Listeria monocytogenes

Sodium lactate (SL) as a potential replacer for potassium sorbate (PS) or sodium benzoate (SB) in comminuted sausages was evaluated. Sausages manufactured with 3.3% SL were compared with a control and 0.05 or 0.1% of PS and SB with regard to its influence on changes of chemical composition, physico-chemical and textural properties, and the growth of inoculated Listeria monocytogenes (LM) stored at 4?°C for up to 8 weeks. The sausages contained 62-64% moisture, 15-17% fat and 12-14% protein with pH range of 6.10-6.15 and water activity (a(w)) range of 0.936-0.941. Sausages containing 3.3% SL alone had lower (P<0.05) thiobarbituric acid reacting substances (TBARS) values than the control and those of PS (0.05-0.1%). Lightness values of sausages varied (P<0.05) among preservatives and storage times, while yellowness values tended to increase with storage time. Textural attributes (springiness and hardness) were reduced after 2 and 6 weeks storage, respectively. Sodium lactate at an incorporation level of 3.3% to sausage formulation had an antilisterial effect similar to those of 0.05-1.0% of PS or SB and delayed the lag phase for the growth of Listeria monocytogenes at least 2 weeks, compared with the control.     

Development of shelf stable pork sausages using hurdle technology and their quality at ambient temperature (37±1°C) storage

Shelf stable pork sausages were developed using hurdle technology and their quality was evaluated during ambient temperature (37±1°C) storage. Hurdles incorporated were low pH, low water activity, vacuum packaging and post package reheating. Dipping in potassium sorbate solution prior to vacuum packaging was also studied. Reheating increased the pH of the sausages by 0.17units as against 0.11units in controls. Incorporation of hurdles significantly decreased emulsion stability, cooking yield, moisture and fat percent, yellowness and hardness, while increasing the protein percent and redness. Hurdle treatment reduced quality deterioration during storage as indicated by pH, TBARS and tyrosine values. About 1 log reduction in total plate count was observed with the different hurdles as were reductions in the coliform, anaerobic, lactobacilli and Staphylococcus aureus counts. pH, a(w) and reheating hurdles inhibited yeast and mold growth up to day 3, while additional dipping in 1% potassium sorbate solution inhibited their growth throughout the 9 days storage. Despite low initial sensory appeal, the hurdle treated sausages had an overall acceptability in the range 'very good' to 'good' up to day 6.     

不同季节中国蜂胶醇提物的化学成分及生物活性

季节是影响蜂胶化学组成和生物活性的生态因子之一。为了解季节对蜂胶品质的影响,以分别来自温带、亚热带和热带地区的不同季节中国蜂胶为材料,采用分光光度法测定其色度、特定吸收率(E1cm)以及总酚、总黄酮、黄酮-黄酮醇和黄烷酮的含量;并测定蜂胶醇提物的抗氧化及抑菌活性。实验结果相关性分析表明:季节对中国蜂胶醇提物(ethanol extract of propolis,EEP)的化学组成有显著影响,中国EEP中总酚、总黄酮、黄酮-黄酮醇和黄烷酮的含量均在7～8月为最高,9月份化学成分含量大多最低,说明其品质在8月总体最好,而9月份,中国蜂胶品质最差。不同季节EEP的总酚和总黄酮含量差异极显著,总酚最大值为(243.87±152.13)mg/g,最小值为(187.25±146.45)mg/g,总黄酮最大值为(189.34±107.51)mg/g,最小值为(122±81.02)mg/g;且季节对EEP的抗氧化活性也有显著影响;EEP的E1cm值与清除DPPH自由基活性和总酚、总黄酮的含量有显著正相关性。而季节对中国EEP的抑菌性没有显著影响。因此,季节对中国蜂胶品质有较大影响。     

Effect of antioxidants on stabilization of meat products fortified with n-3 fatty acids

The effects of an n-3 oil emulsion, with and without added antioxidants, on lipid oxidation in n-3 polyunsaturated fatty acid (PUFA)-fortified meat products were studied. An emulsion of n-3 PUFAs was prepared (25% algal oil, 2.5% whey protein isolates, 10mM sodium citrate, 0.2% potassium sorbate, 500ppm of 70% mixed tocopherols, 100μM EDTA, pH 3, pasteurized at 75°C for 30min) and incorporated into fresh ground turkey, and fresh pork sausage (20% fat) to achieve a concentration of 500mg n-3 PUFA/110g meat. An antioxidant combination containing rosemary (0.2% w/w; radical quencher), citrate (0.5% w/w; sequestrant) and erythorbate (1g/kg product; reductant) was prepared and incorporated into ground turkey patties (5cm dia, 1.5cm thick) or fresh pork sausages (5cm dia, 1.5cm thick). Meat products were stored at 4°C or -18°C and analyzed for color (L*, a*, b* values), lipid oxidation (TBARS and lipid hydroperoxides) and n-3 PUFA profile. a* Values of refrigerated ground turkey patties decreased with storage, and an antioxidant combination effect was observed after 4 days (P<0.05). For fresh pork sausages at 4°C, control+antioxidant (CON+ANTI), and n-3+antioxidant (n-3+ANTI) groups showed greater a* values than controls (CON) indicating that the antioxidant combination stabilized meat color. TBARS and lipid hydroperoxides of both n-3 PUFA-enhanced meat products increased with storage (P<0.05); there were no significant changes in TBARS or lipid hydroperoxides for treatments containing the antioxidant combination (P<0.05). The actual level of n-3 PUFA incorporation in both meat products was greater than 87%; n-3 PUFA concentrations did not change within any treatment during storage (P>0.05). These results provide support for including antioxidant protection in n-3 PUFA fortified meat products.     

Effect of chemical preservatives on shelf life of mushroom (Pleurotus ostreatus) cultivated on cassava peels

Short shelf life is a major impediment to the processing and distribution of mushroom. The effect of chemical preservatives on some quality attributes of mushroom during storage was investigated. Mushroom were soaked in four preservatives at two concentrations for 10 mins, packaged, stored at 4 °C for 30 days and analysed at intervals for their microbial population, colour, firmness and weight loss. Sodium benzoate (0.05%, 0.1%) lost its preservative effect on all the micro‐organisms enumerated after 3 days, and samples treated with 0.1% potassium sorbate had the lowest microbial load at the end of the storage period. Change in colour of the potassium sorbate (0.1%)‐treated sample was lower than and significantly different from the citric acid (2%, 4%)‐treated samples. The values of the firmness of the 4% citric acid preserved mushroom were significantly different (P ≤ 0.05) from other samples throughout the storage period. There was a significant negative correlation (r = ?0.807, P < 0.01) between the firmness and weight loss of the preserved mushroom. Potassium sorbate (0.1%) and citric acid (4%) extended the shelf life of mushroom for 24 days.     

Antioxidant and Antimicrobial Activity of Commercial Propolis Extract in Beef Patties

The objective of this study was to evaluate the efficacy of propolis extract (PE) to reduce lipid oxidation and microbial growth on beef patties during refrigerated storage. Beef patties were manufactured by incorporating PE in 4 different treatments: (1) Control (no PE addition); (2) commercial propolis 1 (2% w/w; CP1); (3) commercial propolis 2 (2% w/w; CP2); and (4) noncommercial propolis (2% w/w; NCP). Raw patties were wrapped with polyvinyl chloride and stored at 2 °C for 8 d. Total phenolic content (TPC), free‐radical scavenging activity (FRS), and polyphenolic content of the PE were evaluated using high‐performance liquid chromatography (HPLC). Lipid oxidation (thiobarbituric acid‐reactive substances (TBARS), conjugated dienes (CnDs), metmyoglobin (MetMb%), pH variation, and color (L*, a*, b*, C*, and h*), and microbial growth (mesophilic and psychrotrophic bacteria) of patty samples were measured. NCP treatment demonstrated the highest FRS (64.8% at 100 μg/mL), which correlated with TPC and the presence of polyphenolic compounds. Lipid oxidation (78.54%, TBARS; 45.53%, CnD; 58.57%, MetMb) and microbial mesophilic and psychrotrophic growth (19.75 and 27.03%, respectively) values were reduced by NCP treatment in refrigerated samples after 8 d. These results indicate that PE has great potential as a natural antioxidant and antimicrobial additive to extend the shelf life of beef patties.     

Effect of grape dietary fibre on the storage stability of innovative functional seafood products made from farmed meagre (Argyrosomus regius)

Two groups of farmed meagre (Argyrosomus regius) sausages were studied regarding quality changes and antioxidant capacity during a 98‐day storage experiment at 2 ± 2 °C. Control sausages contained 3.9% (w/w) of inner pea dietary fibre (IPDF) and the other group contained 0.9% (w/w) IPDF plus 3.0% (w/w) of antioxidant grape dietary fibre (AGDF). The control and AGDF meagre sausages presented a high nutritional value, given their low caloric content, fatty acid profile, amino acid composition and high DF content. Both products were remarkably stable over storage time. The AGDF had an effective antioxidant capacity, proven not only by the radical scavenging activity (90.0–91.0% vs. 82.1–85.4%) and reducing power (8.13–9.10 mg ascorbic acid equivalent g^‐1 vs. 4.16–4.24 mg ascorbic acid equivalent g^?1) measurements, but also by the lower thiobarbituric acid reactive species (TBARS) values (0.78–1.10 vs. 1.50–2.08 mg malonaldehyde kg^?1) over storage time. AGDF seemed to present antimicrobial effect, since on the 63rd day (beginning of significant microbial growth), the control sausages had more than 3 log CFU g^?1 and AGDF sausages much <3 log CFU g^?1. The sensory assessment pointed to some loss of textural quality, more accentuated in the AGDF sausages.     

RESEARCH NOTE: PREPARATION OF FISH SILAGE WITH PHOSPHORIC ACID AND POTASSIUM SORBATE

Silage prepared solely from ground hake frames and ground entrails plus frames (1:4, w/w) acidified to a pH of 4.0 with phosphoric acid and with the addition of 0.1% potassium sorbate underwent enzymatic liquefaction after several weeks storage at 20°C without microbial development. With silage prepared with frames and phosphoric acid but without potassium sorbate, oxidative surface yeasts were the only spoilage microorganisms. With silage prepared from entrails and frames with just phosphoric acid a heavy surface growth of both molds and oxidative yeasts developed.     

The impacts of water and ethanolic extracts of propolis on vacuum packaged sardine fillets inoculated with Morganella psychrotolerans during chilly storage

The impacts of water and ethanolic extracts of propolis at a dose of 0.4 or 0.8% on vacuum packaged sardine fillets inoculated with Morganella psychrotolerans DSM 17886 during storage at 3 ± 1°C for 15 days were investigated. All fish groups were inoculated with M. psychrotolerans (10⁸ cfu/ml) at a rate of 1%. Sensory, colorimetric, chemical analysis (total volatile basic nitrogen, thiobarbituric acid, peroxide values, and free fatty acids), pH value, and microbiological analysis (viable mesophilic and psychrophilic bacteria, coliform, and lactic acid bacteria count) were carried out. An enhance in L* values was found in the group treated with 0.8% ethanolic extracts of propolis on the seventh day of the storage. Application of propolis extract on fish fillets significantly inhibited bacterial growth during storage and extended shelf life of sardine for 4 and 6 days by the use of water extract and for 8 days by the use of ethanolic extract at doses of 0.4 and 0.8%, respectively. The result of the study revealed that application of propolis extracts, mainly ethanolic propolis extracts on sardine fillets resulted in lower lipid oxidation and bacterial growth, therefore, could be natural food additive for preservation of fish fillets.     

Effect of carboxy-hemoglobin on color stability of cooked pork sausage

To investigate the effect of carboxy-hemoglobin (CO-Hb) on the color of cooked pork sausage (CPS), 6 treatments with 5 levels of CO-Hb (0, 0.2, 0.4, 0.6, and 0.8%) and 0.015% NaNO₂ were manufactured. Increased CO-Hb decreased a* values, but increased L* and b* values significantly (p<0.05). Color of the 0.4% CO-Hb samples had no significant change (p>0.05) during the 29-day storage. Both CO-Hb and carboxy-myoglobin (CO-Mb) were found in the pigments extracted from the 0.4% CO-Hb non-cooked sausages. Therefore, CO-Hb showed a potential color agent in the manufacture of sausages.     

Effect of hot-boned pork on the quality of hurdle treated pork sausages during ambient temperature (37 ± 1 °C) storage

The study was aimed at evaluating the suitability of hot-boned pork and pork fat for processing shelf-stable pork sausages using hurdle technology and the different hurdles incorporated were low pH, low water activity, dipping in potassium sorbate solution, vacuum-packaging and post-package reheating. Emulsion stability and cooking yield did not Izatnagardiffer significantly among hot- and cold-processed sausages. Despite the same emulsion pH, the sausages from hot-boned pork had significantly higher fat content. Colour and texture profiles of pork sausages were significantly (P < 0.05) influenced by hot processing. During storage at ambient temperature (37 ± 1 °C), various physico-chemical characteristics, namely pH, TBARS and tyrosine values, of hot- and cold-processed sausages, did not differ. Hot-processing markedly increased the total plate counts of the sausages, but a significant difference was absent for anaerobic counts between treatments at any particular storage interval. Cold-processed sausages had the higher lactobacillus counts throughout the storage period. Sensory evaluation revealed that hurdle-treated pork sausages from hot-boned pork were equally suitable as those from cold-boned pork up to day 6 at ambient temperature.     

蜂胶中有效成分的提取及其抗氧化性能的研究

研究了用乙醇提取蜂胶中有效成分的工艺条件,并对其进行了抗氧化性能的研究。经响应面优化的试验结果表明最佳提取条件为:乙醇浓度为94.51%,提取温度为34.44℃,提取时间为33.86h,料液比为1:15.91。抗氧化试验表明蜂胶的乙醇提取物(EEP)可有效的延缓油脂脂质过氧化反应,通过与维生素E和茶多酚进行比较,其抗氧化性能明显优于二者,表明蜂胶的乙醇提取物是一种很有潜力的天然、安全、高效的油脂抗氧化剂。     

蜂胶醇提物微胶囊的制备及表征

微胶囊具有保护物质免受环境条件影响、掩盖异味和颜色、降低毒性、延长挥发性物质的储存时间,延缓或控制囊心物的释放等功能。本文采用复凝聚技术制备蜂胶醇提物(EEP)海藻酸钠-壳聚糖微胶囊,利用粒度分析仪、激光共聚焦显微镜、红外光谱仪和X射线衍射仪分析、体外释放试验和加速试验等表征微胶囊性状。研究结果表明,制备的EEP微胶囊形状为大小均匀球体,粒径大小为265±25 nm,包埋率和载药量分别达到72.80±3.8%和19.96±2.4%,海藻酸钠和壳聚糖反应形成微胶囊。模拟胃液和肠液条件下体外释放8 h,释放率46.60±0.80%;HPLC分析加速试验EEP微胶囊中7种物质含量变化为14.01%~39.68%,显著低于EEP中37.01%~77.45%。制得的EEP微胶囊粒径小、稳定性良好、释放率符合肠溶体系要求,对EEP中的活性物质具有一定的保护作用。     

Turmeric Extract Rescues Ethanol‐Induced Developmental Defect in the Zebrafish Model for Fetal Alcohol Spectrum Disorder (FASD)

Prenatal ethanol exposure causes the most frequent preventable birth disorder, fetal alcohol spectrum disorder (FASD). The effect of turmeric extracts in rescuing an ethanol‐induced developmental defect using zebrafish as a model was determined. Ethanol‐induced oxidative stress is one of the major mechanisms underlying FASD. We hypothesize that antioxidant inducing properties of turmeric may alleviate ethanol‐induced defects. Curcuminoid content of the turmeric powder extract (5 mg/mL turmeric in ethanol) was determined by UPLC and found to contain Curcumin (124.1 ± 0.2 μg/mL), Desmethoxycurcumin (43.4 ± 0.1 μg/mL), and Bisdemethoxycurcumin (36.6 ± 0.1 μg/mL). Zebrafish embryos were treated with 100 mM (0.6% v/v) ethanol during gastrulation through organogenesis (2 to 48 h postfertilization (hpf)) and supplemented with turmeric extract to obtain total curcuminoid concentrations of 0, 1.16, 1.72, or 2.32 μM. Turmeric supplementation showed significant rescue of the body length at 72 hpf compared to ethanol‐treated embryos. The mechanism underlying the rescue remains to be determined.     

中温乳化香肠中一株优势腐败菌的分离鉴定与生物学特性

以中温乳化香肠为研究对象,对其在25 ℃贮藏过程中的优势腐败菌进行分离鉴定,并通过管碟法和酶标比浊法测定肉制品中常用的7 种防腐剂对腐败菌的抑制效果。结果表明,中温乳化香肠在25 ℃贮藏第25天时,菌落总数已超过GB 2726-2005《熟肉制品卫生标准》中规定的菌落数,从该腐败样品中分离得到1 株优势腐败菌CMRC BC-1,根据形态学、生理生化特征和16S rDNA序列比对结果,该菌株被鉴定为凝结芽孢杆菌。7 种防腐剂中,乳酸链球菌素（Nisin）对该菌株具有明显的抑菌活性,添加量为0.1 g/L时,其抑制率达到99.05%;其余6 种防腐剂除山梨酸钾外,在各自的最大添加量时对该菌株均具有一定的抑制作用。     

Pectin lyase and polygalacturonase of Aspergillus niger pathogenic for yam tubers (Diascorea rotundata)

Polygalacturonase and pectin lyase of Aspergillus niger partially purified by ethanol, ammonium sulphate precipitation, DEAE-cellulose and Sephadex G-150 column chromatography were characterized. Polygalacturonase gave optimum activity at pH 4–5, and at 35°C. It was stable at pH 3–7 and at 20–50°C. The molecular weight was 38020. For pectin lyase optimum activity occurred at pH 5 and 45°C. The enzyme was stable at pH 3–4 and at 40–50°C. The molecular weight was 30 900. Yam tissue was optimally macerated at pH 4–5 by the enzymes. At pH 4.5, potassium sorbate (0.6 mg/ml), benzoic acid (0.8 mg/ml) and sodium benzoate (1.0 mg/ml) caused complete inhibition of polygalacturonase activity. With pectin lyase, this effect was achieved with potassium sorbate and benzoic acid each at 0.9 mg/ml, but not with sodium benzoate.     

Effect of Sodium Acid Pyrophosphate in Combination with Sodium Nitrite or Sodium Nitrite/Potassium Sorbate on Clostridium botulinum Growth and Toxin Production in Beef/Pork Frankfurter Emulsions

Combinations of sodium acid pyrophosphate (SAPP) with added sodium nitrite and/or potassium sorbate were tested at various pH levels to determine effectiveness in delaying Clostridium botulinum growth and toxin production in frankfurter emulsions. Formulations containing sodium nitrite (40 ppm), potassium sorbate (0.26%) and SAPP (0.4%) resulted in a greater delay of toxin production (12–18 days) than other combinations (6–12 days) having similar pH values. Treatments containing 0.4% SAPP appeared to be more inhibitory than their counterparts without SAPP, displaying less numbers of toxic samples during the 53-day storage period at 27°C. Aerobic mesophilic colony counts and residual nitrite data showed little difference among treatments.     

Inhibitory effect of propolis extract on the growth of Listeria monocytogenes and the mutagenicity of 4‐nitroquinoline‐N‐oxide

Propolis originates from a resinous substance collected by honeybees from the buds and leaves of trees and plants, which is then mixed with pollen as well as enzymes secreted by the bees. In the present study, the susceptibility of Listeria monocytogenes to the ethanol extract of propolis (EEP) as influenced by EEP concentration, incubation temperature, pH, and cell age was investigated. In addition, the antimutagenic action of EEP against 4‐nitroquinoline‐N‐oxide (4‐NQO) was also examined. Results revealed that EEP at a dosage of 7.5 µg mL^?1 or higher exerted a bactericidal effect on L. monocytogenes. L. monocytogenes was most susceptible to EEP at 37 °C followed by 25 and 4 °C. At acid pH values, cells of the test organism were more sensitive to EEP than at neutral pH, while most resistant at alkaline pH values. Cell age was also found to affect the susceptibility of L. monocytogenes to EEP. Cells in the mid‐exponential phase showed the highest susceptibility, followed by cells in the late‐exponential phase and stationary phase. EEP caused cell leakage of the test organism. A marked increase in the absorbance at 260 nm, UV‐absorbing material in the supernatant of cell suspension, and irregularly shaped materials around the cell surface were noted after cells of L. monocytogenes were exposed to EEP. Furthermore, EEP at a dosage of 7.5–60.0 µg per plate was found to suppress 4‐NQO‐induced mutation by 17.6–88.8%. Copyright © 2006 Society of Chemical Industry     

Effect of Antioxidants and Cooking on Stability of n-3 Fatty Acids in Fortified Meat Products

ABSTRACT: This study was carried out to determine the effect of processing and cooking on n-3 polyunsaturated fatty acid (PUFA) stability and to determine the efficacy of antioxidants (ANTI) to minimize lipid oxidation in cooked n-3 PUFA-fortified meat products. An emulsion of n-3 PUFAs (25% algal oil) was incorporated into ground turkey, pork sausages, or restructured hams (500 mg n-3 PUFA/110 g meat) with or without an "antioxidant cocktail" containing citrate (0.5% w/w), erythorbate (1 g/kg product), and rosemary (0.2% w/w). Ground turkey and pork sausages were frozen 2 d, then cooked to 71°C, and stored at 4°C for 2 d. Cooked, restructured hams were sliced, vacuum packaged, and stored at 4°C, or frozen and thawed with subsequent storage at 4°C. Treatments were CON (control), n-3 (n-3 PUFAs), CON + ANTI and n-3 + ANTI. Products were analyzed for color, lipid oxidation (TBARS and peroxide values), and n-3 PUFA profile. TBARS of n-3 PUFA-fortified treatments in ground turkey and pork sausages increased with storage ( P < 0.05); there were no changes in TBARS for CON + ANTI and n-3 + ANTI groups ( P > 0.05). For restructured hams nitrite curing appeared to delay lipid oxidation such that antioxidant treatment effects were unobservable ( P > 0.05). Overall recovery of n-3 PUFAs after heat processing was 69% to 85%, and there was no effect of storage on n-3 PUFA concentration in raw or cooked products ( P > 0.05). Sensory scores for n-3 treated restructured hams were lower than controls ( P < 0.05). Results suggested that cooking resulted in some losses of n-3 PUFAs in fortified meat products and that an "antioxidant cocktail" protected against lipid oxidation during subsequent storage in non-cured meat products.     

Effect of sage (Salvia officinalis) on the oxidative stability of Chinese-style sausage during refrigerated storage

The objective of this study was to assess the effect of sage, at levels of 0.05%, 0.1% and 0.15% (w/w), on the oxidative stability of Chinese-style sausage stored at 4 °C for 21 days. The results showed that inclusion of sage in sausages resulted in lower L* values (P < 0.05) and higher a* values (P < 0.05) compared to the control. During refrigerated storage, sausages containing sage showed significantly retarded increases in TBARS values, and in the formation of protein carbonyls (P < 0.05), but showed accelerated losses of thiol groups (P < 0.05). Addition of sage to the sausages at levels of 0.1% and 0.15% reduced textural deterioration during refrigerated storage (P < 0.05). Sage used in this study had no negative effects on the sensory properties of sausages.