| As the aging process of the population is accelerating,the physiological health of the elderly is more and more concerned by the society.Muscle attenuation is a potential threat to the physical health of the elderly.Meat is the source of high-quality protein.A moderate increase of meat supplementation and resistance exercise can help the elderly to delay the muscle attenuation.However,due to the poor chewing ability of the elderly and the coarse muscle fiber of meat,it is not suitable for the elderly to the chewing and swallowing of meat products.Therefore,fristly through the measurement of muscle attenuation of the elderly and the effect of meat diet in this paper,the correlation can be revealed between the reduction of meat diet and the attenuation degree.Then,ultrasonic assisted low salt curing(reducing Na salt,adding Ca salt)was used to optimize the beef quality,so as to adapt to dietary characteristics of the elderly.Finally,the effects of ultrasonic assisted low sodium salting on the distribution of water molecules and protein secondary structure in meat were studied by using low field NMR and Raman spectroscopy.The main results are as follows:1.Measurement of muscle attenuation and chewing ability in the elderly and the effect of meat diet on itIn this chapter,the elderly were divided into muscle attenuation group and normal group,and each of group consists of three age stages including 60-69 years old,70-79 years old and≥ 80 years old.The aim of our work was to study the relationship between muscle attenution and meat diet in the elderly.The results of analysis indicated that there were extremely significant differences on gender and body mass index(BMI)between the muscle attenuation group and normal group(P<0.01).Within muscle attenuation group,the degree of muscle attenuation increased with age,SMI(skeletal muscle mass index)value decreased.The analysis of dietary status and exercise status showed that there were significant differences on meat and related protein intake,livestock and related poultry protein intake,and the amount of exercise in some of the three age groups of the muscle attenuation group and normal group(P<0.05).A decreasing trend appeared with the increase of classification value(P<0.05).Muscle attenuation was related to meat and related protein intake(β=-2.633、P<0.05;β=-2.216、P<0.05).Meat intake was a protective factor of muscle attenuation for the elderly(OR<1).Comparing chewing ability of different age group the elderly,the bite force of 65-74 years old people was lower than 60-64 years old for 14.29%,and the bite force of 75-year-old people was lower than 60-64 years old for 59.52%.Those data showed the decrease trend of chewing ability for old people with age.The texture of meat products should be reformed to targetly adapt chewing ability for elderly people.2.Study on texture of ultrasound assisted low sodium salt curing beefIn this chapter,ultrasonic wave with power of 1200W and frequency of 25kHz was used to marinate beef at 10±1 ℃ for 170 min,which was to explore the effect of low salt curing on the quality of beef with ultrasonic.The results showed that ultrasonic treatment had tenderizational effct on marination of beef evidenced by the improved beef texture,significantly reduced beef shear force,hardness and chewiness(P<0.05).Calcium salt had inhibited effect on sodium salt.The content of sodium salt in ultrasonic treatment group was significantly lower than that of control group(P<0.05).The cooking loss of ultrasonic treatment group was not increased compared with control group and static treatment group.Principal component analysis showed among the ultrasonic treatment group,4.8%NaCl+1.2%calcium chloride group and 4.8%NaCl+1.2%calcium lactate group were distributed in the negative end of the first component,and 4.8%NaCl group was distributed in the positive end of the first component.4.8%NaCl+1.2%calcium lactate group was distributed in the positive end of the second component,and 4.8%NaCl group and 4.8%NaCl+1.2%calcium chloride group was distributed in the negative end of the second component.Combining with the load diagram result of each indicator of ultrasonic assisted low-sodium cured beef,it showed that 4.8%NaCl group,4.8%NaCl+1.2%calcium chloride group,and 4.8%NaCl+1.2%calcium lactate group had a smaller shear force value.The relatively high sodium content of 4.8%NaCl group indicated that ultrasonic wave could tenderize and promote the penetration of sodium salt.Comparing shear forces of same group of meat samples under different cooking time,for 6%NaCl group,4.8%NaCl+1.2%calcium chloride group,and 4.8%NaCl+1.2%calcium lactate group,has lower shear forces at 10 h.It indicated that cooking effect was better when cooking time was 10h.As to the shear forces of different groups of meat samples under the same cooking time,when cooking times of 4.8%NaCl+1.2%calcium lactate group were 9 h,10 h and 11h,their shear forces were significantly lower than that of 6%NaCl group(P<0.05).It indicated that ultrasonic wave combined with calcium lactate treatment can effectively promote the tenderizing effect of low temperature and slow cooking on beef.Comparing the satisfaction degree among 4.8%NaCl+1.2%calcium lactate group,6%NaCl group and 4.8%NaCl+1.2%calcium chloride group,the results showed that the highest satisfaction rate of the 4.8%NaCI+1.2%calcium lactate group was 37.21%and the lowest dissatisfaction rate was 0.On the significant level of 1%,samples of 6%NaCl group were the most hard,followed by 4.8%NaCl+1.2%calcium chloride group and 4.8%NaCl+1.2%calcium lactate group.This indicated that when the tender time of low temperature and slow cooking low sodium salt curing beef was 10 h,the tender degree of 4.8%NaCl+1.2%calcium lactate group was more suitable for chewing of 65 to 74 elderly people.3.Effect of ultrasound assisted low sodium salt curing on beef’s water distribution and protein secondary structureIn this chapter,ultrasound assisted low sodium salt curing beef were detected by low-field Nuclear Magnetic Resonance Imaging(NMR)and Raman Spectroscopy,which was to explore the water distribution and secondary structure characteristics of beef meat protein.The results showed that the content of free water(P23)of raw and cooked beef did not change significantly after the ultrasound assisted low sodium salt curing.It indicated that ultrasound assisted low sodium salt curing had no obvious effect on the free water of the beef.Comparing with the control group,it was found that the strength of the raman band near 545 cm-1 of the myofibrin was increased,it indicated that the conformation of disulfide bond in the beef was increased.At 760 cm-1,the tryptophan ring stretched and vibrated,and the relative strength of the peak increased significantly(P<0.05).The content of a-helix decreased significantly(P<0.05),β-folding content increased,the ordered secondary structure decreased and the disordered structure increased.It indicated that the changes of protein structure in ultrasound assisted low sodium salt curing were reflected in the transformation from spiral structure to folding structure,as well as the partial transformation from ordered structure to disordered structure in general.This result provided a strong evidence for the tenderizing effect of ultrasound assisted low sodium salt curing beef in chapter two. |
PDF Full Text Request