Physico‐Chemical and Structural Characteristics of Vegetables Cooked Under Sous‐Vide,Cook‐Vide,and Conventional Boiling

In this paper, physico‐chemical and structural properties of cut and cooked purple‐flesh potato, green bean pods, and carrots have been studied. Three different cooking methods have been applied: traditional cooking (boiling water at 100 °C), cook‐vide (at 80 and 90 °C) and sous‐vide (at 80 °C and 90 °C). Similar firmness was obtained in potato applying the same cooking time using traditional cooking (100 °C), and cook‐vide and sous‐vide at 90 °C, while in green beans and carrots the application of the sous‐vide (90 °C) required longer cooking times than cook‐vide (90 °C) and traditional cooking (100 °C). Losses in anthocyanins (for purple‐flesh potatoes) and ascorbic acid (for green beans) were higher applying traditional cooking. β‐Carotene extraction increased in carrots with traditional cooking and cook‐vide (P < 0.05). Cryo‐SEM micrographs suggested higher swelling pressure of starch in potatoes cells cooked in contact with water, such as traditional cooking and cook‐vide. Traditional cooking was the most aggressive treatment in green beans because the secondary walls were reduced compared with sous‐vide and cook‐vide. Sous‐vide preserved organelles in the carrot cells, which could explain the lower extraction of β‐carotene compared with cook‐vide and traditional cooking. Sous‐vide cooking of purple‐flesh potato is recommended to maintain its high anthocyanin content. Traditional boiling could be recommended for carrots because increase β‐carotenes availability. For green beans, cook‐vide, and sous‐vide provided products with higher ascorbic acid content.     

Consumer Acceptability and Sensory Profile of Cooked Broccoli with Mustard Seeds Added to Improve Chemoprotective Properties

Broccoli, a rich source of glucosinolates, is a commonly consumed vegetable of the Brassica family. Hydrolysis products of glucosinolates, isothiocyanates, have been associated with health benefits and contribute to the flavor of Brassica. However, boiling broccoli causes the myrosinase enzyme needed for hydrolysis to denature. In order to ensure hydrolysis, broccoli must either be mildly cooked or active sources of myrosinase, such as mustard seed powder, can be added postcooking. In this study, samples of broccoli were prepared in 6 different ways; standard boiling, standard boiling followed by the addition of mustard seeds, sous vide cooking at low temperature (70 °C) and sous vide cooking at higher temperature (100 °C) and sous vide cooking at higher temperature followed by the addition of mustard seeds at 2 different concentrations. The majority of consumers disliked the mildly cooked broccoli samples (70 °C, 12 min, sous vide) which had a hard and stringy texture. The highest mean consumer liking was for standard boiled samples (100 °C, 7 min). Addition of 1% mustard seed powder developed sensory attributes, such as pungency, burning sensation, mustard odor, and flavor. One cluster of consumers (32%) found mustard seeds to be a good complement to cooked broccoli; however, the majority disliked the mustard‐derived sensory attributes. Where the mustard seeds were partially processed, doubling the addition to 2% led to only the same level of mustard and pungent flavors as 1% unprocessed seeds, and mean consumer liking remained unaltered. This suggests that optimization of the addition level of partially processed mustard seeds may be a route to enhance bioactivity of cooked broccoli without compromising consumer acceptability.     

Thermal Denaturation in Fish Muscle Proteins During Gelling: Effect of Spawning Condition

We studied thermal denaturation of myofibrillar proteins from pre-and post-spawning hake by differential scanning calorimetry (DSC), and evaluated denaturation kinetics under both conditions. The denaturation enthalpies of all pre-spawning fish muscle extracts were less than those from post-spawning. The area under the DSC thermogram corresponding to myosin denaturation was smaller in myofibrillar extracts from pre-spawning than from post-spawning hake, while the areas corresponding to denaturation of actin were similar. Between 40 and 55°C the myosin denaturation rates were greater for post-spawning than for pre-spawning hake. Both entalphies and kinetic data indicated proteins of fish in a better biological condition (post-spawned) denature more rapidly and completely.     

TEXTURE AND COLOUR CHANGES IN MEAT DURING COOKING RELATED TO THERMAL DENATURATION OF MUSCLE PROTEINS1

Differential scanning calorimetry was used to select temperatures that diferentiated between thermal denaturation of the three major structural protein species in bovine muscle: myosin, collagen and actin. Samples of m. semimembranosus, m. semitendinosus and m. psoas major were heated to those different temperatures and evaluated sensorially. Three groups of sensory properties were needed to describe the main texture changes observed in the meat: 1. Firmness 2. Fiber cohesivity, bite-off force, residual bolus 3. Juiciness Firmness increased with thermal denaturation of the myofibrillar proteins (myosin; 40-60d?C and actin; 66-73d?C). Fiber cohesivity etc. decreased with collagen denaturation (56-62d?C). Reduction in juiciness was primarily associated with actin denaturation, while cooking loss increased over the whole temperature range. The property “total chewing work”, a composite of the first two texture groups mentioned, yielded like the judges' “total texture preference”, optimal texture in the 60-67d?C temperature region, implying denatured myosin and collagen but native actin. This meat was light pink-gray in colour, while the cooking juice released was dark red.     

Physiochemical and Microbiological Quality of Lightly Processed Salmon (Salmo salar L.) Stored Under Modified Atmosphere

Low‐temperature cooking, such as sous vide, has become a favored method for processing seafood. For this method to be applicable for retail products, combinations with other processing steps are needed to keep the products safe and durable while maintaining high quality. The present experiments were designed to investigate the influence of low‐temperature treatment (40, 50, or 60 °C) in combination with various packaging technologies (modified atmosphere [MA] or soluble gas stabilization [SGS]) on both the microbial growth and the physiochemical quality. Salmon loins were either kept natural or inoculated with Listeria innocua prior to drying (16 to 18 hr) in either 100% CO₂ (SGS) or atmospheric air (MA packaging). All samples were sous vide treated, repackaged in MA, and stored at 4 °C for 24 days. The results showed shelf life to be significantly improved with the implementation of SGS, by prolonging the lag‐phase and slowing the growth rate of both naturally occurring and inoculated bacteria. Variations in packaging technology did not significantly influence any of the tested quality parameters, including drip loss, surface color, and texture. Growing consumer demand for lightly processed seafood products makes Listeria spp. an increasing problem. The present experiment, however, has shown that it is possible to lower processing temperatures to as little as 40 or 50 °C and still obtain inhibition of Listeria, but with improved chemical quality compared to traditional processing.     

Thermal Gelation Properties of Protein Fractions from Pork and Chicken Breast Muscles

Thermal gelation properties of myosin, actin, myofibrils (MF), sarcoplasmic protein (SP) and connective tissue (CTS) from pork semimem-branosus and chicken breast (CB) were evaluated. Gels were prepared at pH 6.0, 2% NaCl and cooked to 70°C at 0.7°C/min. Pork myosin had a higher gel strength and a lower cooking loss than CB myosin at 7% protein. Actin from both species did not form a measurable gel. MF gels from pork and CB had the lowest cooking loss while CTS and SP had the highest cooking loss. Difference in gel strength between muscle and MF+SP+CTS at 7% protein was not consistent with that at 10% protein.     

Enhancement of safety and quality of ready-to-cook Asian green mussel using acidic electrolyzed water depuration in combination with sous vide cooking

Emerging technologies were combined to ensure the safety for consumers of Asian green mussel (AGM; Perna viridis). The combination of acidic electrolyzed water (AEW) depuration and sous vide cooking effectively reduced Vibrios while maintaining the quality of mussel. The use of AEW depuration combined with sous vide cooking at 100 °C for 1 min (D/SV-1) provided the yield of mussel meat of 27.22%, maintained the color, and texture properties. It could prevent the oxidation of polyunsaturated fatty acids and caused no changes in patterns of main proteins including paramyosin, actin and tropomyosin. Vibrio parahaemolyticus, V. vulnificus and Shewanella algae in AGM without treatment were 4.12, 3.00 and 3.30 log₁₀ CFU/g, respectively. Those bacterial species were confirmed by MALDI Biotyper® technique. They were potentially inactivated by the selected process. In addition, the next generation sequencing (NGS) based on the 16S rRNA gene revealed a low percentage of V. vulnificus genome (2.72%) and the complete elimination of other naturally existing Vibrios. Overall, AEW depuration of raw mussels, followed by sous vide cooking could be a promising method for the production of safe ready-to-cook Asian green mussels for consumption.Industry relevanceCommon Asian green mussel (AGM; Perna viridis) may represent a risk for public health associated with pathogenic bacteria originating from the aquatic environment. It also deteriorates rapidly within 1–2 days because of its perishable nature, thus losing its market value. To tackle such problems, appropriate pretreatment using acidic electrolyzed water depuration, followed by sous vide cooking under proper conditions could be implemented for safety assurance of ready-to-cook AGM by eliminating both pathogenic and spoilage bacteria. Also, the eating quality could be maintained. As a consequence, the technology developed in the present study could offer an effective solution for ensuring customer safety without compromising eating quality. It could be commercially employed for seafood processing industry, especially for bivalve mollusks, e.g., mussels, scallops, and clams.     

DETERMINATION OF THE QUALITY AND SHELF LIFE OF SOUS VIDE PACKAGED BONITO (SARDA SARDA,BLOCH, 1793) STORED AT 4 AND 12C

ABSTRACT

The aim of this study was to determine the quality and shelf life of sous vide bonito stored at 4 and 12C. The total volatile basic nitrogen (TVB‐N) values of cold stored samples exceeded the recommended limit on 35th day of storage, while they were unacceptable according to sensory scores. The TVB‐N and trimethylamine‐N values of sous vide samples stored at 12C exceeded the limits at the 18th day, while sensory scores were very close to the acceptability limit. For all samples, mesophilic and psychrophilic bacterial counts exceeded the limits after they were regarded as spoiled. Therefore, the shelf life of the sous vide bonito, cooked at 70C for 10 min, was 28 days at 4C while 15 days at 12C. It was seen that sous vide packaging provided a long shelf life for bonito.

PRACTICAL APPLICATIONS

Sous vide is a long established but relatively little known cooking process. The data regarding the effect of storage temperature on shelf life and quality of sous vide fish are very limited. Therefore, this study aimed to determine the sensory, microbiological and chemical quality of sous vides packaged bonito during refrigerated storage (4 ± 1C) and abuse temperature conditions (12 ± 1C). The results of this study can be utilized by researchers in future studies as well as by manufacturers to determine the processing and storage conditions of sous vide fish.     

Concentration of Umami Compounds in Pork Meat and Cooking Juice with Different Cooking Times and Temperatures

This study examined the concentrations of umami compounds in pork loins cooked at 3 different temperatures and 3 different lengths of cooking times. The pork loins were cooked with the sous vide technique. The free amino acids (FAAs), glutamic acid and aspartic acid; the 5′‐nucleotides, inosine‐5′‐monophosphate (IMP) and adenosine‐5′‐monophosphate (AMP); and corresponding nucleoside inosine of the cooked meat and its released juice were determined by high‐performance liquid chromatography. Under the experimental conditions used, the cooking temperature played a more important role than the cooking time in the concentration of the analyzed compounds. The amino acid concentrations in the meat did not remain constant under these experimental conditions. The most notable effect observed was that of the cooking temperature and the higher amino acid concentrations in the released juice of meat cooked at 80 °C compared with 60 and 70 °C. This is most likely due to the heat induced hydrolysis of proteins and peptides releasing water soluble FAAs from the meat into the cooking juice. In this experiment, the cooking time and temperature had no influence on the IMP concentrations observed. However, the AMP concentrations increased with the increasing temperature and time. This suggests that the choice of time and temperature in sous vide cooking affects the nucleotide concentration of pork meat. The Sous vide technique proved to be a good technique to preserve the cooking juice and the results presented here show that cooking juice is rich in umami compounds, which can be used to provide a savory or brothy taste.     

Process optimisation of pulsed electric fields pre-treatment to reduce the sous vide processing time of beef briskets

This study used multiple regression to model the effect of pulsed electric field (electric field strengths 0.7, 1.0 or 1.5 kV cm⁻¹) and sous vide (60 °C for either 12, 18 or 24 h) processing on the quality parameters (tenderness, cooking loss, colour, lipid stability) of beef brisket. Pulsed electric fields (PEF) at 0.7 kV cm⁻¹ and 1.5 kV cm⁻¹ followed by sous vide processing for 12–20.2 and 20.8–23.7 h, respectively gave the lowest values for hardness (<20.2 N), shear force (100.5 N mm⁻¹ s⁻¹) and cooking loss (<17.4%). PEF treatment prior to sous vide processing had no significant effect on lipid oxidation, colour stability, cooking loss or in vitro protein digestibility of sous vide-processed brisket. Increasing the electric field strength and/or prolonging the sous vide time significantly increased collagen solubilisation in the sous vide brisket. This study demonstrated that a PEF pre-treatment can reduce sous vide processing time while enhancing the tenderness of tough meat cuts.     

Characteristics of pressurised pork meat batters as affected by addition of plasma proteins,apple fibre and potato starch

Pork meat (low‐fat) batters were prepared without and with the addition of three non‐meat ingredients: (blood) plasma proteins, (dietary) apple fibre and potato starch. The batters were processed by cooking‐alone (70 °C) and by high‐pressure/temperature combination (400 MPa/70 °C). Protein denaturation and starch gelatinisation through the different processings were followed by differential scanning calorimetry. Batter characteristics such as water holding (weight loss) and different texture parameters (texture profile analysis) were used as quality criteria for comparisons among different formulations and processes. Plasma proteins and apple fibre behaved as inert fillers in both kinds of processed batters. Potato starch effects depended on processing conditions to the extent that these influenced the degree of gelatinisation. In pressurised batters (pressure and heating in sequence), regular preservation effects against subsequent thermal denaturation of proteins were observed. Differential scanning calorimetry revealed that starch was also pressure‐preserved from subsequent thermal gelatinisation, which was confirmed by scanning electron microscopy. The presence of native‐like proteins and ungelatinised starch produced cumulative softening effects in pressurised batters. © 2000 Society of Chemical Industry     

Thermal Properties of Proteins in Chicken Broiler Tissues

The thermal behavior of breast and thigh muscles, blood and skin tissues of chicken broilers was evaluated by differential scanning calorimetry (DSC). Onset temperature of transition (T_o), maximum thermal transition (T_max) temperatures, and denaturation enthalpy (ΔH) were evaluated. Breast muscle exhibited a complex thermogram with five endothermic transitions at 57°C, 63°C, 67°C, 73°C, and 78°C at a heating rate of 10°C/min. Thigh muscle exhibited only three major transitions at 60°C, 66°C, and 76°C. Thermal curves of isolated protein fractions indicated that the thermal transitions in muscle corresponded to the denaturation of myosin, sarcoplasmic proteins, collagen and F-actin. An increase in the heating rate from 1.0° to 40°C/min significantly elevated the onset temperature of transition and major transition temperatures, as well as the enthalpy of denaturation. Enthalpy of the muscle system heated to various end-point temperatures, cooled and reheated, showed that myosin was completely denatured at 60°C, sarcoplasmic proteins at 70°C and actin at 80°C.     

Sous Vide加工方法对牦牛肉品质的影响

以牦牛肉背最长肌为原料,采用Sous Vide加工方法,研究不同热处理温度、热处理时间和肉块厚度对牦牛肉感官品质、蒸煮损失率、质构及微观结构的影响。在单因素试验基础上,进行正交优化试验,确定Sous Vide加工牦牛肉的最佳工艺条件。结果表明：Sous Vide加工方法对牦牛肉感官品质、剪切力、蒸煮损失率影响较大,通过正交试验得到Sous Vide加工牦牛肉的最佳工艺条件为热处理温度70 ℃、热处理时间135 min、肉块厚度3.0 cm;经Sous Vide处理的牦牛肉肌纤维束结构变得松散,肌纤维密度降低,肌束膜部分结构被破坏,牦牛肉嫩度和感官品质均优于对照组。     

Extractability and thermal stability of frozen hake (Merluccius merluccius) fillets stored at −10 and −30 °C

The relationship between thermal stability changes and functionality loss was monitored in hake muscle fillets stored for 40 weeks at ?10 and ?30 °C. The evolution of changes in apparent viscosity, dimethylamine formation and extractability of muscle proteins in NaCl, sodium dodecyl sulphate (SDS) or SDS plus mercaptoethanol showed drastic differences as a function of temperature. At the higher storage temperature, both myosin heavy chain and collagen were the most severely unextracted in salt and SDS solutions, with actin becoming unextractable at the end of storage. Differential scanning calorimetry showed differences with storage time and temperature in both onset temperature and thermal denaturation enthalpy, mostly affecting the myosin transitions. Some protein denaturation occurred with little or no functionality loss. A considerably high fraction of hake muscle proteins remained in the native‐like condition even at the higher frozen storage temperature. In these conditions both apparent viscosity and myosin and actin extractability in NaCl were very low. © 2002 Society of Chemical Industry     

HEAT TREATMENT EFFECT ON TEXTURE CHANGES and THERMAL DENATURATION of PROTEINS IN BEEF MUSCLE

Meat tenderness is one of the most important quality criteria when evaluating results of cooking conditions. Changes in tenderness and weight losses of heat-treated meat (semitendinosus muscle) for different time-temperature combinations were analyzed; the relationship between protein denaturation and textural changes was studied.
Heat treatments of meat samples (1.5 cm in diameter, 2 cm long) were performed in a thermostatic bath in the 60–90C range. Maximum heating times were 180 min. Meat hardness was determined by Warner-Bratzler measurements using an Instron testing machine. Protein denaturation was followed by Differential Scanning Calorimetry (DSC) analyzing peaks for myosin (I and II), sarcoplasmatic proteins and collagen (II) and actin (III).
Between 60 and 64C, hardness decreased with cooking time until reaching the lowest asymptotic values. This was related to protein denaturation of peak I and II. Between 66 and 68C, hardness decreased at first but increased later due to actin denaturation; at the temperatures 81 and 90C no modifications were observed and hardness remained at its higher values.
The kinetic model proposed fit the experimental results satisfactorily. Activation energies of tenderizing and toughening processes are similar to those of protein denaturation of peak II and III. Weight losses due to cooking were also modelled increasing through the entire temperature range.     

Thermal Denaturation and Aggregation of Proteins in Minced Fish as Studied by a Thermomechanical Method

A thermomechanical method of heating and mixing, was developed to study directly protein denaturation and aggregation in minced fish. It is based on simultaneous and continuous measurement of torque and temperature in a meat sample mixed while being heated. The torque and temperature were continuously recorded. From curves thus obtained, thermal denaturation temperatures of minced samples from 6 marine fish species were determined. The curves showed 4-6 peaks at 32-38°C, 44-46°C, 52-56°C, and 62-75°C, presumably corresponding to denaturation of myosin, actomyosin, sarcoplasmic proteins, and actin, respectively. The temperature range of peak 1 was 4-5°C higher in fatty fish (herring, mackerel) than in lean fish (cod, blue whiting).     

Effect of heating temperature and duration on the texture and protein composition of Bighead Carp (Aristichthys nobilis) muscle

The effect of heating temperature and duration on the texture and protein composition of bighead carp (Aristichthys nobilis) muscle was investigated. Samples were heated at 90°C, 100°C, 110°C, and 120°C for different times. The results showed that cooking loss increased significantly with increasing temperature and heating time, and a fractional conversion model was used to describe the increase. Hardness, chewiness, and gumminess exhibited a similar four-phase change with two peaks at 90°C, 100°C, and 110°C, and the trend was not observed at 120°C. Analysis of sodium dodecyl sulfate polyacrylamide gel electropheresis (SDS-PAGE) revealed that contents of myosin heavy chain decreased entirely to disappear and contents of actin significantly decreased. Increasing the intensity of the heavy molecular weight bands indicated the aggregation of myosin. Content of water-soluble proteins presented an increasing trend, which reflected the protein degradation and the release of low-molecular-weight compounds.     

Protein Denaturation in Pork Longissimus Muscle of Different Quality Groups

Differential scanning calorimetry (DSC) was used to investigate the protein denaturation characteristics of pork muscles from four quality groups namely RFN (red, firm, and non-exudative), RSE (red, soft, and exudative), PFN (pale, firm, and non-exudative), and PSE (pale, soft, and exudative). The thermograms indicated three endothermic peaks between 45°C to 90°C, corresponding to denaturation of myosin (peak I), sarcoplasmic proteins (peak II), and actin (peak III). The myosin peak was much reduced in PSE samples, while the actin peak remained almost identical in all groups. RFN and RSE samples were found to have very similar protein denaturation characteristics and were not significantly different in their thermodynamic protein denaturation parameters. PFN samples showed similar myofibrilar protein denaturation but significantly different sarcoplasmic protein denaturation characteristics compared to normal (RFN) samples according to their DSC thermograms. Based on these findings, it was suggested that the pale color in PFN pork is linked to sarcoplasmic protein denaturation.     

Carrageenan Effects on Thermal Stability of Meat Proteins

Meat myofibrillar protein (MP) gels and ground pork were used as model systems for studying thermal transition temperatures. Addition of up 2% of κ, ι, or λ carrageenan (CGN) to MP caused a very slight change in the thermal denaturation of the meat proteins. Three transition temperatures were found in ground pork samples, which were characteristic of myosin (59.4°C), sarcoplasmic proteins (67.8°C), and actin (82.4°C). Mixtures of high ionic strength had lower thermal transition peaks. CGN did not cause major shifts in transition temperatures, suggesting that molecular interactions between CGN and meat proteins did not occur.