Physicochemical Changes Occurring During Storage of Precured Beef Blends at Different Temperatures and Two Levels of Salt

Preblends of lean beef (20% water, 75 ppm nitrite, 3 or 6% salt) were stored at -10, 0 and 15°C and samples were analyzed at 0, 1, 2 and 3 days of storage. Emulsifying capacity (per 100 mg of total protein) was not significantly different between the 3 and 6% salt levels; and, was not significantly affected by storage temperature but decreased with storage time. The viscosities of the extracts were not significantly affected by the amount of added salt or the temperature of storage; however, they increased significantly during storage. Water-holding capacity increased significantly with the quantity of salt and length of storage time. Correlation analysis resulted in a negative correlation between pH and viscosity and a positive correlation between pH and salt soluble proteins. Surprising was the significant negative correlation between emulsifying capacity and water-holding capacity.     

Quality Characteristics of Broiler Chicken Meat on Salt at Different Temperatures

The aim of this investigation was to compare the quality characteristics and muscle structure of broiler chicken meat stored at different temperatures in the retail market in Oman. The meat quality characteristics of broiler breast meat were analysed. Ten samples were randomly selected from each group of fresh, frozen, and chilled chicken meat. Colour L?, a?, b?, pH, expressed juice, cooking loss, sarcomere length, W-B-shear force and muscle structure (using scanning electron microscopy) were determined. Fresh meat samples had significantly (P < 0.05) lower pH values and lightness L? than those of chilled and frozen samples. The chilled meat samples were significantly (P < 0.05) lighter and had lower shear force values than fresh and frozen samples. Frozen samples had significantly (P < 0.05) higher expressed juice and cooking loss values than either fresh or chilled samples. The pH values of fresh, chilled, and frozen breast samples were related to colour and expressed juice. Electron microscopy demonstrated that the changes in the physical properties of the chilled meat were related to breakdown of the muscle fiber bundles. The quality characteristics of broiler meat from different storage temperatures varied significantly.     

不同冻结温度下牛肉的肌原纤维蛋白变性与肌肉持水性

为明确冷冻温度对牛肉肌原纤维蛋白变性和肌肉持水性（water-holding capacity,WHC）的影响、探讨肌 原纤维蛋白变性与WHC的相关性。以牛背最长肌作实验材料,探究－9、－18、－23、－38 ℃下冻结后肌原纤维 蛋白理化特性和牛肉WHC。通过测定巯基含量、蛋白质溶解度、Ca2＋-三磷酸腺苷酶（adenosine triphosphatase, ATPase）活力及蛋白质热稳定性考察牛肉冻结后肌原纤维蛋白变性情况,利用解冻汁液流失与加压失水率指标衡 量牛肉WHC,采用低场核磁共振（low field-nuclear magnetic resonance,LF-NMR）波谱和磁共振成像（magnetic resonance imaging,MRI）技术对比分析了肌肉水分分布情况,并于4 ℃解冻后测定了色差与剪切力。结果表明： －23 ℃与－38 ℃下冻结试样较－9 ℃与－18 ℃肌原纤维蛋白变性程度小：－23 ℃与－38 ℃下冻结试样蛋白质溶解 度、Ca2＋-ATPase活力、巯基含量和总变性焓相比－9 ℃与－18 ℃实验组较高（P＜0.05）。－23 ℃与－38 ℃下冻 结牛肉解冻后L*值、b*值、剪切力、解冻汁液流失和加压失水率显著低于－9 ℃与－18 ℃（P＜0.05）。LF-NMR 及MRI结果相互佐证了肉样在－23 ℃与－38 ℃冻结下肌肉WHC高于－9 ℃与－18 ℃的实验结果。肌原纤维蛋白理 化特性（蛋白质溶解度、Ca2＋-ATPase活力、巯基含量、总变性焓）与WHC（解冻汁液流失率、加压失水率）均呈 极显著相关（P＜0.01）,L*、b*值及剪切力亦与WHC存在极显著相关（P＜0.01）。相关性分析结果验证了牛肉冻结 过程中肌原纤维蛋白变性对肌肉持水性存在显著影响,进而导致牛肉解冻后出现肉色劣变、嫩度下降及汁液流失。     

Use of Bicarbonates for Microbial Control and Improved Water-Binding Capacity in Cod Fillets

Dipping cod fillets in ammonium or sodium bicarbonate solutions markedly reduced microbial growth compared to untreated samples after 8 days at 4°C. Total plate counts, proteolytic bacteria and H₂S-producing bacteria were inhibited. Mixing ammonium- and sodium bicarbonates at selected ratios maintained the preservative effect while reducing the ammonia odor. The treated fish had improved texture and moisture retention by both objective and subjective testing but had significantly lower aroma and overall acceptability scores from sensory evaluation.     

不同贮藏温度对黄桃采后品质和抗氧化能力的影响

本文主要研究了低温贮藏对黄桃果实贮藏品质和抗氧化能力的影响。黄桃采后预冷12 h,在0、4和10℃三个不同低温条件下进行贮藏。结果表明,0℃贮藏的黄桃采后腐烂率和褐变率均为0,显著低于4和10℃(P<0.05)。与4和10℃相比,0℃贮藏还可以明显抑制膜透率的升高,且贮藏期品质、抗氧化酶活性以及总抗氧化能力均保持在较高水平。在0℃下贮藏,果实能够维持较好的硬度、总糖、可溶性固形物、可滴定酸、维生素C、总酚和总黄酮的含量;同时0℃贮藏抑制了多酚氧化酶和过氧化物酶活力,而且有利于抗氧化酶维持较高的活性,缓解果实冷害。4和10℃下,硬度和维生素C含量显著下降(P<0.05),丙二醛含量显著上升(P<0.05)。采用聚类分析和主成分分析进行数据分析,聚类分析可以将19种生理和品质指标分为两个明显的独立簇,与主成分分析的结果大体一致,即14～21 d是不同温度贮藏的品质劣变点,且第一主成分可以很好地将硬度、维生素含量、可滴定酸含量与其他指标分开,这体现出黄桃果实品质指标和生理指标间的相似性与差异性。因此,0℃贮藏可以显著保持黄桃采后品质和抗氧化能力。     

Theoretical Prediction of the Water Activity of Standard Saturated Salt Solutions at Various Temperatures

A theoretical approach was used to predict the water activity (a_w) at 15°C and 35°C of selected saturated salt solutions used as standards in the range of microbial growth (～0.57–0.97). For this purpose a rigorous thermodynamic model to predict osmotic coefficient was used. The results agreed very well with experimental measurements at 15°C and 35°C for most salts studied, which included NaBr, NaCl, (NH₄)₂SO₄, KCl, BaCl₂, and K₂SO₄. For KNO₃ the agreement at the higher temperature was somewhat less satisfactory and the reasons for this behavior are discussed.     

两种贮藏温度下“黑琥珀”李果实品质及不同部位抗氧化活性的变化规律

研究不同贮藏温度下李果实品质以及近果皮与近果核部位果肉抗氧化能力的变化。结果表明,在20℃贮藏时,李果实硬度、超氧阴离子自由基、羟自由基和DPPH 自由基清除能力不同程度降低,而pH 值、总抗氧化能力、总酚和总黄酮含量升高,2℃贮藏可显著延缓李果实硬度、超氧阴离子自由基、羟自由基和DPPH 自由 基清除能力的降低,以及pH 值、总抗氧化能力、总酚和总黄酮含量的升高;相关性分析的结果表明,李果实中酚类、黄酮类物质含量与总抗氧化能力具有极显著相关性(P ＜ 0.01);李果实近果皮及近果核处果肉的总抗氧化能力、羟自由基清除能力、总酚及总黄酮含量均存在显著性差异;李果实SSC 与近果皮果肉总抗氧化能力、清除超氧阴离子自由基及DPPH 自由基能力、总酚含量的相关系数大于近果核,而pH 值与近果核处总抗氧化能力、清除超氧阴离子自由基及羟自由基能力、总酚及总黄酮含量的相关系数大于近果皮果肉。李果采后品质劣变可能与清除超氧阴离子自由基、羟自由基及DPPH 自由基能力的降低有关。     

不同成熟度红毛丹果实果肉品质特性及抗氧化活性比较

以海南"保研-7号"红毛丹果实为实验原料,在其成熟度分别为三、五、七和十成熟(或称为成熟度30%、50%、70%和100%)时采摘;测定了上述红毛丹果实果肉品质及抗氧化活性指标,包括可溶性固形物(TSS)、可滴定酸(TA)、还原糖、还原型抗坏血酸(As A)及总抗氧化能力、羟自由基(·OH)清除能力、抗坏血酸过氧化物酶(APX)、过氧化氢酶(CAT)、过氧化物酶(POD)、多酚氧化酶(PPO)等酶活性,以评估成熟度对红毛丹果实果肉品质及抗氧化能力的影响。结果表明:七成熟时,TSS含量17.01%、As A含量278.13μg/g均最大、总抗氧化能力151.04 U/g、·OH清除能力79.16%、APX 1.31×104 nmol/(min·g)活性以及CAT 99.86 U/g活性最强,而TA含量最小0.53%、还原糖含量最低57.44 mg/g;而五成熟时,POD活性最大12.22 U/g而PPO活性最小7.33 U/g。综上,不同成熟度的红毛丹果实果肉品质及抗氧化能力存在显著差异;七成熟为海南"保研-7号"红毛丹果实的适宜采收期。本研究结果能为红毛丹采后商品化处理技术体系的完善及贮运保鲜中的品质保持提供理论和技术依据。     

Growth of Clostridium sporogenes and Staphylococcus aureus at Different Temperatures in Cooked Corned Beef Made with Reduced Levels of Sodium Chloride

Cooked corned beef made with normal (ca.2.5%) or a reduced (ca.1.5%) level of salt were inoculated with either clostridial spores or with staphylococci and incubated at temperatures ranging from 5 - 30°C. Growth of indigenous microflora, staphylococci, or clostridia was similar at both salt levels at a given incubation temperature. However, increasing the abuse temperature greatly increased the growth of all organisms. Outgrowth of clostridial spores occurred in ground cooked corned beef which contained the normal residual nitrite of 40 - 45 ppm; readdition of nitrite to 150 ppm at the time of inoculation markedly reduced growth. Gas production was not a good indicator of clostridial growth.     

Physical and Sensory Properties of Block Processed Cheese with Formulated Emulsifying Salt Mixtures

Abstract

Various emulsifying salt mixtures were used in making block type processed cheeses. Ras cheese was used as the cheese base with two salt mixtures: (i) Na-diphosphate + Na-polyphosphate + Na-tripolyphosphate and (ii) Na-poly-phosphate + Na-citrate + Na-orthophosphate + Na-diphosphate comparing to commercial salts Joha SE and PZO respectively. The resultant processed cheeses were analyzed when fresh and monthly during storage at 7 and 20°C for water activity (a _w ), oil separation, meltability, flow behavior, color parameters, and sensory properties. There were no significant differences in water activity values among all treatments. The differences were significant in oil index and meltability values. The samples exhibited different shear stress values and it was highest in treatments with commercial salts. Consistency coefficient (k-value) of processed cheese samples was affected by emulsifying salt mixture being almost two folds higher with salt mixtures (i) than those of salt mixtures (ii). The color parameters L, a, b, Chroma and hue angle showed slight differences among treatments and the cheese was shinier and whiter with increasing pyrophosphate content in the salt mixture. The stored samples became less white especially when stored at room temperature (20°C). Sensory evaluation showed that all cheeses were acceptable but the most acceptable samples were produced with mixtures in the ratio of (i) 30:40:30 and (ii) 50:20:20:10.     

Texture and Microstructure of Block Type Processed Cheese with Formulated Emulsifying Salt Mixtures

Block-processed Ras cheese was produced with two salt mixtures: (1) Na-diphosphate+Na-polyphosphate+Na-tripolyphosphate in ratios 40 : 50 : 10, 30 : 40 : 30 & 30 : 30 : 40 and (2) Na-polyphosphate+Na-citrate+Na-orthophosphate+Na-diphosphate in ratios 50 : 20 : 20 : 10, 40 : 10 : 20 : 30 & 30 : 10 : 20 : 40. Commercial salts Joha SE and PZO were used for comparison, respectively. Texture profile analysis and microstructure (LM and TEM) of resultant cheeses were studied. Chewiness, gumminess, adhesiveness, and hardness showed a significant difference and the cheese samples exhibited higher values during storage. The values were highest in the samples stored at room temperature. Light microscopy photographs indicated different emulsification degree with various emulsifying salt mixtures. These observations were confirmed with the image analysis and TEM. Among the entire treatments, mixture (1) in ratio 30 : 40 : 30 and mixture (2) in ratio 40 : 10 : 20 : 30 gave the best and close texture to the commercial salts and can be recommended in the production of block processed cheese.     

Pre- and Post-Rigor Sectioned and Formed Beef Steaks Manufactured with Different Salt Levels, Mixing Times and Tempering Times

This study was designed to identify processing parameters necessary for the incorporation of pre-rigor beef in sectioned and formed steaks. Meat logs were prepared from pre- or post-rigor beef muscle with 0.0, 0.5 or 1.0% salt, mixed for 0, 6, 12 or 18 min, frozen and tempered to —3°C. Logs were pressed and cleaved after 0, 24, 48 or 72 hr tempering. Tempering at -3°C resulted in sufficient metabolic activity (as measured by pH and R-value) to deplete the ATP content of pre-rigor muscle. The presence of salt hastened the onset of rigor, maintained a higher ultimate muscle pH and improved cooking yields, bind (adhesion) and tenderness. Longer mixing times enhanced bind. These data suggest that, with appropriate modification in the processing procedure, pre-rigor muscle can be incorporated into sectioned and formed products.     

不同持水性冷却肉的品质比较和蛋白质的DSC测定

用聚类分析方法将18个样品聚为两(类)组--低汁液流失率组和高汁液流失率组。组间持水性和L值差异显著,但a值和嫩度没有差异。DSC测定和相关分析结果显示:高汁液流失率组的肌浆蛋白和肌球蛋白的变性程度大于低汁液流失率组;持水性与肌球蛋白和肌浆的变性程度成显著负相关;用DSC方法测定蛋白质变性程度比用测定蛋白质溶解性的方法更灵敏。     

Changes in the Bifringent Characteristics of Cereal Starch Granules at Different Temperatures and Water Activities

Small angle light scattering has been used to study the major and abrupt changes in birefringence that occur on gelatinization. The effects of annealing and added solutes can be readily followed. In addition, more subtle modifications which reflect changes in order in the granules can be examined. This has been exemplified by the gelatinization behaviour under conditions of reduced water activity. These results are compared with those of other authors using the equation developed by Flory to describe the effect of diluent upon the order/disorder transition in polymers.     

不同食盐添加量对冷藏草鱼品质的影响

以草鱼背部白肌肉为实验材料,研究了不同食盐添加量(质量分数为 0%、0.5％、2.5％、5.0%)对于鱼肉在冷藏(0℃,1、6、13d)期间品质变化的影响。双因素方差分析结果表明,冷藏时间以及食盐对鱼肉的pH值、丙二醛含量和总挥发性盐基氮含量具有显著影响(P<0.05),且双因素对pH值和丙二醛含量的影响没有显著的交互作用。添加质量分数为2.5%和5.0%的食盐,使得鱼肉的pH值显著低于对照组(0% NaCl)、丙二醛含量平均值分别高于对照组28%~189%和120%~322%, 显示促氧化作用;但添加质量分数为0.5%的食盐对脂肪氧化有抑制作用,使得冷藏6、13d后鱼肉的丙二醛含量下降18%~31%。食盐浓度和冷藏时间对鱼肉的色泽(L*、a*、b*值)影响很小。鱼肉的总挥发性盐基氮含量在冷藏期间的增加符合一级反应动力学模型(R² 为0.9701~1.0000),其反应速率常数(0.0498~0.0894d-1)随食盐浓度的增加而降低。     

酸度调节剂协同水分保持剂对牛肉盐溶蛋白凝胶保水性的影响

该文采用正交设计的方法研究焦磷酸钠(sodium pyrophosphate,SPP)、三聚磷酸钠(sodium tripolyphosphate,STP)、六偏磷酸钠(sodium hexametaphosphate,SHP)及柠檬酸钠(sodium citrate,SC)对牛肉盐溶蛋白凝胶保水性的影响。结果表明:SPP、STP、SHP、SC的最佳质量配比为2∶2∶2∶3,添加量为0.5%时,保水率可达94.03%。将不同条件处理的盐溶蛋白溶液进行十二烷基磺酸钠-聚丙烯酰胺凝胶电泳(sodium dodecyl sulphate-polyacrylamide gel electrophoresis,SDS-PAGE),发现盐溶蛋白凝胶保水性的差异是由于蛋白质含量的不同所致。     

Physicochemical Properties of Sweetpotato Starches with Different Gelatinization Temperatures

Physicochemical properties of five sweetpotato starches differing in gelatinization temperature were examined. The gelatinization temperature of Koganesengan starch, an ordinary cultivar of sweetpotato in Japan, was 73.6°C, whereas those of the other starches were measured to be 71.6°C for Kyukei 96162–1, 65.8°C for Kyushu No.127, 63.9°C for Kyukei 240, and 54.9°C for Quick Sweet. Some relationships of the primary structural properties with the gelatinization temperature have been found. As the gelatinization temperature decreased: i) the content of phosphate groups attached to the glucosyl residues decreased, ii) the amylose content, which was determined as difference in long chains of debranched original starch and of its amylopectin, decreased, iii) the proportion of unit chains with DP > 100 in the amylopectin fraction increased, iv) the proportion of unit chains with DP 6 to 10 in the amylopectin fraction increased, whereas that of unit chains with DP 12 to 24 decreased, v) the B‐type crystallinity of the starch granules was enhanced, and vi) the proportion of longer chains constituting each Nägeli amylodextrin increased. Moreover, it was found that thin pastes of the low temperature‐gelatinizing starches retrograded slower during cold storage than the ordinary starch. Among the starches, Quick Sweet starch granules, having the lowest gelatinization temperature, were digested rapidly by pancreatin.     

不同温度养殖的雌体三疣梭子蟹性腺和蟹肉风味品质比较

研究常温养殖与加温养殖对雌体三疣梭子蟹性腺和蟹肉的风味影响,测定2 组蟹性腺和肉中的主要滋味物质,并进行电子舌、电子鼻和感官评价的分析。结果表明：电子舌和电子鼻均可对不同水温养殖三疣梭子蟹的性腺以及蟹肉进行有效区分;加温养殖会提高鸟苷酸（guanosine monophosphate,GMP）和腺苷酸（adenosinemonophosphate,AMP）对性腺滋味的贡献,使总游离氨基酸含量有所减少,呈味氨基酸和必需氨基酸百分比有所上升。对蟹肉而言,加温组GMP、肌苷酸、AMP相比常温组增加了0.40、0.66 倍和3.46 倍,呈味氨基酸、必需氨基酸和总游离氨基酸的含量显著升高（P＜0.05）,味精当量值与常温组相比增加0.59 倍。感官评价表明,加温养殖组性腺的肥满度和气味评分有一定的提高,蟹肉的整体感官品质明显高于常温组。     

Effects of Salt Levels in Prerigor Blends and Cooked Sausages on Water Binding, Released Fat and pH

Prerigor pork was used to make preblends of 0, 1, 2, 3 or 4% salt and 125 ppm sodium nitrite. Sausages formulated with 1.5 or 2.0% salt were made from all preblends; sausages formulated with 1.0% salt were made from preblends of 0, 1, 2 and 3% salt. Sausages made with nonsalted preblends had less water binding capacity (WBC) and more released fat (RF) than sausages made with preblends of 2, 3, or 4% salt (P < 0.05). Levels of salt in preblends did not affect (P > 0.05) WBC when salt contents of sausages were reduced from 2.0 to 1.5%; however, these WBC values were lowered somewhat when preblends with 0 or 1.0% salt were used. Water binding capacity decreased (P < 0.05) when salt contents of sausages were reduced from 1.5 to 1.0%, and when these sausages were made with preblends containing 2.0 or 3.0% salt. Data suggest that salting of prerigor pork is beneficial for optimizing WBC in sausages made with low salt contents.