Changes in broiler breast fillet tenderness, water-holding capacity, and color attributes during long-term frozen storage

ABSTRACT:  Freezing is the most common and efficient way to maintain the quality of poultry products for long periods of time. However, tougher texture, discoloration, and drying have been reported as a result of long-term frozen storage. The impact of freezing on the tenderness, water-holding capacity, and color of broiler breast fillets was investigated for up to 8 mo. A total of 160 birds were deboned at either 2 or 6 h postmortem (PM). All deboned left fillets were frozen and stored at –18 °C for up to 8 mo, while the corresponding right fillets were assessed for texture approximately 24 h after deboning as a control measurement without any freezing treatment. Tenderness was measured by the Meullenet–Owens razor shear. Thaw loss, cooking loss, moisture content, color, and muscle shape profiles were also evaluated. No difference in tenderness was observed during the first 2 mo compared to the control (0 mo), but significantly decreased between 2 and 4 mo. The 8-mo-old fillets were the least tender, with a 31.5% increase in shear energy between 4 and 8 mo. Moisture content of cooked meat gradually decreased, showing a significant drop between 2 and 6 mo of storage, while thaw and cooking loss consistently increased over the entire storage period. The color of the frozen fillets tended to be darker, redder, and less yellow than the control, with increased storage duration. The results suggest that for optimal tenderness, frozen broiler breast fillets are best consumed within 2 mo of freezing.     

ELECTROMYOGRAPHIC STUDY ON COOKED RICE WITH DIFFERENT AMYLOSE CONTENTS

The texture of six varieties of cooked rice with different amylose contents was measured with a Texturometer. Masticatory behavior of the rice was evaluated using electromyography (EMG) of masticatory muscles. Differences in mastication patterns among the seven subjects examined were greater than between rice varieties. Masticatory behavior was more related to the adhesiveness and stickiness of rice as measured using a Texturometer than to the hardness. The number of chews and masticatory time, total duration of mastication and total muscle activities were highly correlated with each other, and were greater in cooked rice with a high amylose content, which showed low adhesiveness and stickiness values using a Texturometer. Cooked rice with a high amylose content was masticated with high masseter muscle activities. The ratio of jaw-opening muscle activity to the preceding jaw-closing muscle activity was low in high-amylose varieties, which corresponds to the ratio of stickiness to hardness using a Texturometer. Between-sample differences in mastication parameters were more apparent in the early stage of mastication, and no significant diference was observed in the late stage.     

Changes in Tenderness, Color, and Water Holding Capacity of Broiler Breast Meat during Postdeboning Aging

ABSTRACT:  The impact of postharvest aging on the tenderness, color, water holding capacity, and appearance of broiler breast fillets after deboning was investigated. A total of 360 broilers were processed and deboned at either 1.5-, 3-, or 6-h postmortem (PM) and aged at 4 ± 1 °C for up to 6 d. Tenderness was predicted by the Meullenet–Owens razor shear. Drip loss, cook loss, color, and muscle-shape profiles were also evaluated during the 6-d aging duration. Deboned fillets were in the tenderness range corresponding to "neither tough nor tender" for the first 2 d of aging and changed into "slightly tender" after 3 d of aging according to the instrument-tenderness perception equivalent scale. Tenderization due to postdeboning aging seemed to be more pronounced for fillets deboned in a prerigor state (that is, 1.5- and 3-h PM). Over the aging period, tenderness improved by 6.9 and 7.4 percentage points for the 1.5- and 3-h PM treatments, respectively, while those fillets deboned in a postrigor state (6-h PM) exhibited no significant difference in tenderness. Drip and cook loss of fillets consistently increased over the aging period. The color of fillets tended to become less red and more yellow during aging although there was no significant difference in  L *. Overall, the tenderizing effects of deboned broiler breast fillets during the storage of 6 d were minimal but seemed to be affected by fillet height and length as determined through analysis of covariance (ANCOVA) and K-means clustering analysis. Thicker and tougher fillets were more susceptible to the tenderizing effects during postdeboning aging.     

TEXTURE ANALYSIS OF BEEF COOKED AT VARIOUS TEMPERATURES BY MECHANICAL MEASUREMENTS, SENSORY ASSESSMENTS AND ELECTROMYOGRAPHY

The potential of mechanical measurements, sensory assessments and electromyography (EMG) to detect the variation in texture properties of beef induced by cooking at temperatures of 45–80C was determined. The mechanical behaviour of meat, from two Semimembranosus muscles from one animal, was studied by compression and shear tests in destructive and nondestructive conditions. Electromyographs from the masticatory muscles of 14 trained subjects were recorded during mastication of the meat samples. Texture profiles were completed at the end of each masticatory sequence. Increase in cooking temperature produced an overall increase in shear and compression parameters as well as in meat elasticity. Sensory hardness and total muscle work developed during mastication also increased with cooking temperature. Mechanical measurements, EMG parameters and sensory assessment of texture were highly correlated. EMG, on which the influence of psychological factors is limited, can be used to characterise meat texture objectively.     

MEAT TEXTURE CHARACTERISATION: COMPARISON OF CHEWING PATTERNS, SENSORY AND MECHANICAL MEASURES

The texture of beef, varied by muscle (semimembranosus and semitendinosus), myofibrillar status (ageing time and cold-shortening) and cooking temperature (60C and 80C), was determined by a sensory profile, chewing patterns (determined from surface electromyograms) and mechanical properties of the cooked meats measured at low and high deformation in compression, shear (cutting) and by dynamic (viscoelasticity) tests. The meat factors were discriminated differently by the different measurements showing that they detected differently the various origins of meat texture. Only the maximum modulus before 70% compression and sensory assessments and EMG gave discrimination among all the meat factors. Two main sensory dimensions were found from the profile: juiciness and tenderness with a third related to the determination of elasticity. Juiciness, which varied most between cooking temperatures, was better related to mechanical parameters at low strain rather than high strain and to initial muscular activity rather than later muscular activity. Conversely, tenderness was better related to high strain mechanical properties and to measurements in the middle or later part of the mastication process suggesting that tenderness assessment requires structural disintegration of meat.     

Electromyography of Eating Apples: Influences of Cooking, Cutting, and Peeling

ABSTRACT: The mastication of 7 differently prepared apple samples (raw pieces peeled and unpeeled, sliced, grated, cooked pieces with and without peel, and half-cooked pieces, 10 g each) was evaluated using electromyography (EMG). Eleven subjects participated in the EMG recording of both sides of the masseter and temporal muscles while eating samples normally. Only the grated sample reduced the number of chewing strokes and muscle activity before swallowing. In contrast, the thin apple slices produced significantly shorter contraction duration and cycle time only during the 1st 5 chewing strokes. The EMG duration and cycle in subsequent chews, as well as the other parameters, did not significantly differ between slices and pieces. Cooked apples exhibited significantly lower EMG amplitude and muscle activity per chew than their raw counterparts; however, there was no evidence of reduced total muscle activity required for swallowing. Raw and cooked apples with peel yielded significantly greater EMG amplitude and longer duration than those without peel. These findings suggest that appropriate preparation is necessary for people with various mastication abilities: grated for very low ability, cooked for those with weak chewing force, and unpeeled for mastication training.     

Training and Sensory Judgment Effects on Mastication as Studied by Electromyography

Electromyography recordings (EMG) were performed on 10 naive and 10 trained subjects during mastication of different samples of beef. For each group of subjects, ordinary mastication was compared to mastication accompanied by tenderness assessment of the chewed sample. Trained subjects showed a larger variation in muscle work than a naive group when chewing. Sensory assessment modified more the mastication profiles of trained subjects than those of naive ones and these variations occurred at the beginning of the masticatory sequence. EMG was useful for comparing mastication of different groups of panelists and appeared to be an interesting alternative for information about texture perception of naive subjects.     

The relationship between chewing activity and food bolus properties obtained from different meat textures

During chewing, a meat sample is mashed under compression and shear bite forces whilst saliva is incorporated. The resulting mixture is shaped into a cohesive bolus by agglomeration of small particles to trigger a swallow. This study aims to investigate the relationship between meat structure before chewing and texture after various chewing durations, according to the subject's chewing behavior. Twenty-five young adults participated. Electromyography activity (EMG) was recorded from surface electrodes on the elevator muscles during mastication of cold beef (5 g). Two different meat textures were obtained by varying aging and cooking temperature. Subjects were asked to chew and then to spit out the bolus either after a constant chewing duration (7 s) or when the bolus was ready to be swallowed. Boluses were then weighed to determine saliva incorporation. Cutting tests were applied to measure maximum shear force and to assess bolus structure homogeneity. From EMG recordings, temporal and amplitude parameters were analyzed. The mechanical shear force was maximal for meat before chewing and decreased for the bolus with the lengthening of the chewing duration. Significant texture differences were found for samples before chewing and for two types of bolus but differences were larger for the bolus after 7 s chewing than for the bolus when ready to be swallowed. The amount of saliva incorporated into the bolus increased with both chewing muscular activity and chewing duration. Finally, the more chewing cycles before swallowing, the more comminuted the meat bolus (lower shear force) and the more saliva was incorporated in it. These results fit with one of the major roles of the saliva, that is, to provide cohesion between particles [Nature 391 (1998) 329] and with the intra-oral management of meat during chewing as analyzed by videofluorography [Arch. Oral Biol. 47 (2002) 267].     

Comparison of electromyographic pattern of sensory experts and untrained subjects during chewing of Mahon cheese

Use of electromyography (EMG) to monitor mastication is a relatively new concept in assessing food physical and sensory properties. Although expert assessment of cheese characteristics is widely used, the effect of training in sensory analysis on mastication patterns, as assessed using EMG is not well known. Nine samples of the same Mahon cheese (60 days ripening) were given to 24 subjects (8 experts, 16 untrained) and EMG recorded for each chewing sequence. Three samples were tested in a single session by each subject, and three sessions carried out on different days. EMG was recorded from four masticatory muscles for each subject. From EMG records the following was extracted: number of chews, chewing time, mean and maximum voltage of EMG bursts (i.e. chews) across chewing sequence, chewing work and chewing rate. No gender bias was found for the EMG parameters considered, therefore, as regards gender, each group was considered to be homogeneous. Variability within-subjects across samples was greater for experts than untrained subjects. Significant differences in chewing time, chewing work and chewing rate were found between the expert and untrained groups. Data analysis of the three sessions showed an influence of cognitive constructs, mediating states, on the chewing process. The experts were found to be goal driven as to their mastication process. Experts showed no significant differences between sessions, untrained subjects were found to vary their EMG output in successive sessions for number of chews, chewing time, mean voltage, and chewing work.     

A comparison between two methods (Warner-Bratzler and texture profile analysis) for testing either raw meat or cooked meat

Two methods for assessing texture characteristics of meat (Warner-Bratzler (WB) - and texture profile analysis (TPA)), both performed either on raw or on cooked meat, were tested in 96 samples of m. longissimus dorsi muscle of eight heifers and eight bulls, aged 1, 3 or 6 days post-mortem. A sensory analysis was also performed on 96 samples. Sensory variates were predicted by instrumental variates as follows: hardness was better predicted by TPA than by WB; springiness was only predicted by WB; juiciness was only significantly predicted by TPA; greasiness was always poorly predicted, but the prediction was better with TPA, and the number of chewings was also better predicted with TPA. Results suggested the convenience of performing a TPA for assessing meat texture as, in cooked meat, only TPA furnished highly significant correlations for hardness, for juiciness and for the number of chewings. Although WB could predict hardness and springiness, only the equation for the prediction of the number of chewings was useful (r(2)=0.171, P<0.004). It seems that texture parameters, assessed by a TPA and performed on cooked meat, are the best predictors of sensory texture in bovine meat.     

猪肉质构的仪器测定与感官评定之间的相关性分析

以熟肉为研究对象,比较感官评定和两种仪器测定方法(剪切法和质构剖面分析)之间的差异和关联性。结果表明:剪切力与感官评定的硬度、多汁性呈显著相关性(r=0．73、-0．71);质构剖面分析硬度与感官评定的硬度相关性显著(r=0．81),质构剖面分析的粘聚性与感官评定的弹性、多汁性、油性分别呈显著相关性(r=-0．79、-0．67、-0．81)。通过建立仪器分析与感官评定间的数学模型,本实验提示质构剖面分析更能全面预测猪肉感官品质。进一步的实验参数验证了质构剖面分析回归方程预测的准确性。     

EFFECTS OF BINDING SUBSTRATE, TYPE OF NONMEAT ADDITIVE AND METHOD OF TENDERIZING ON CURED CHICKEN ROLLS

Chicken rolls were manufactured using ground dark fowl meat or mechanically deboned poultry meat as a binding substrate, sodium caseinate or soya isolate and a meat block that was mechanically tenderized or chunked. Effects of these treatments on yield, chemical composition, sensory and texture profile attributes were evaluated in this study. Inclusion of soya isolate increased the cook yield and improved color over sodium caseinate (P < 0.05). Likewise, rolls containing ground-dark fowl meat were lighter in color than those made with mechanically deboned poultry meat. Rolls made with mechanically deboned poultry meat had greater chewiness, while those made with sodium caseinate had greater cohesiveness. Texture profile analysis indicated that mechanical tenderization was the predominant factor in producing a softer and more springy chicken roll. Sensory evaluation revealed that mechanical tenderization decreased chewiness as compared to cubing (P < 0.05).     

Mechanical and gelling properties of comminuted sausages containing chicken MDM

The present investigation focuses on the physicochemical properties, rheological behaviors and texture of raw and cooked emulsions containing different mechanically deboned meat (MDM) from chicken. MDMs were produced from the neck, backs and thighs. The texture and mechanical profile analyses were performed using a small deformation dynamic oscillation in a shear and instrumental texture analyzer. The mechanical spectra of the raw and cooked MDM emulsion gels were classified as weak gels based on their frequency sweep and tan δ results. Both the G′ and G″ values increased with increasing frequency in the temperature of 4 and 10 °C. The MDM from thighs had the lowest water holding capacity (WHC) and emulsifying (EC) values, while the MDM from backs had significant values of 2.41 and 128.87, respectively. The cooked emulsion containing backs showed the highest hardness and cohesiveness values, while the emulsion containing necks and thighs had the lowest texture parameters.