| Pleurotus eryngii is rich in nutrients and is named for its fatty texture and similarity to abalone meat,but there is still a gap between it and the real meat.Previous research found that its texture is closer to that of abalone muscle after repeated freezing and thawing.In this study,Pleurotus eryngii substrates were used as raw materials,and repeated freeze-thaw treatment was used as a pretreatment method combined with heat treatment to simulate the texture of abalone muscle in raw and cooked states,respectively.The effects of different conditions of freeze-thaw treatment and freeze-thaw-heating treatment on the texture properties(shear force and TPA)were investigated,from which the best parameters for simulating the reference were selected.The changes in the properties and structures of the samples under different processing conditions were investigated by measuring the macroscopic representations such as water holding capacity,cooking properties,appearance morphology and sensory characteristics,and the analysis of the microscopic morphology,moisture state,migration pattern and spatial distribution of the samples by SEM,LF-NMR and MRI.It can provide theoretical reference for the development and utilization of new simulated meat products,and provide a reference for the quality regulation of related products in actual production.The main findings of this study are as follows:1.The effects of freeze-thaw cycle treatments on the textural properties and water holding capacity of simulated meat products of Abalone mushroom were investigated.The trends of the textural properties(shear force,TPA)of the simulants were studied under different thawing methods,freezing temperature,freezing time and number of freeze-thaw cycles,compared with the TPA textural properties of the reference fresh abalone muscle.Freeze-thaw conditions were obtained that were more similar to the texture of reference: refrigerated thawing,freezing temperature-20°C,freezing time 24 h,and freeze-thawing cycles of 1 and 3 times.It was found that the texture of the samples with different thawing methods was significantly different,possessing higher shear force and structural compactness when thawed by refrigeration;compared with-40°C,the samples had lower hardness,gumminess and chewiness when frozen at-20°C;with increasing freezing time,hardness,springiness,gumminess,chewiness,resilience and structural compactness decreased,and cohesiveness first increased and then decreased;shear force,structural compactness,hardness,gumminess,chewiness and resilience properties were negatively correlated with the number of freeze-thaw cycles,when cohesiveness was positively correlated with it.The effects of different conditions on the water-holding capacity and morphological appearance of the samples were investigated.It was found that higher thawing temperature,longer freezing time,higher freezing temperature and increased number of freeze-thaw cycles led to the decrease of water-holding capacity and deterioration of the color.2.The effects of combined freeze-thaw-heating treatment on the textural properties and water-holding capacity of simulated meat products of abalone mushroom were investigated.The changes in textural properties(shear force,TPA)of the simulants with different heating time,temperature and methods were examined,and compared with the texture of cooked abalone muscles,and the best simulation parameters were obtained as follows: refrigerated thawing,freezing temperature-20℃,freezing time 24 h,1freeze-thaw cycle,and cooking at 90℃ for 12 min.it was found that with the increase of heating time and temperature,the samples’ shear force,structural compactness,hardness,cohesiveness,gumminess,chewiness and resilience of the samples tended to decrease;comparing the samples heated after 0,1 and 3 freeze-thaw cycles,it was found that the heating did not eliminate the effects produced by freeze-thawing pretreatment,and the shear force,hardness,springiness and cohesiveness were higher and the gumminess and chewiness decreased after freeze-thawing for 1 time,and the texture of simulants were closer to cooked abalone muscles heated under the same condition.The effects of different conditions on water-holding capacity,cooking characteristics,appearance and morphology and sensory evaluation of the samples were studied.As the damage degree of heating increased,water-holding capacity decreased,shrinkage in all directions inproved significantly,color deteriorated,and L~* and whiteness values declined.Samples heated after 0,1 and 3 freeze-thaw cycles were compared,and samples heated after 1freeze-thaw cycle had higher moisture content and sensory scores,better thermal stability and color.The overall shrinkage was lower than that of the directly heated samples.3.To investigate the effects of freeze-thaw and freeze-thaw-heating treatments on the moisture distribution and microstructure of simulated meat products of abalone mushroom.The effects of treatment conditions on the moisture state,spatial distribution and microstructure of typical samples were investigated.And the results showed that the freeze-thaw treatment mainly reduced the proportion of bound water,which disappeared after three freeze-thaw cycles;the heating treatment had a greater effect on the proportion of non-fluid water,and its content was negatively correlated with the heating time and temperature,and decreased significantly at 16 min and 100℃.Comparing the samples heated after 0 and 1 freeze-thaw cycles,it can be seen that the peak where the bound water is located disappears and the content of non-fluid water decreases when heated directly at 90°C;while samples heated after 1 freeze-thaw cycle can retain most of the content,which indicates that the freeze-thawing pretreatment is beneficial to the maintenance of water during heating.Some of the macroscopic property changes can be explained using the SEM image of the samples,indicating that the microstructure changes can have an impact on the properties and quality of the samples.The direct heating of the samples at 90℃ almost collapsed the internal organization,while samples heated after 1 freeze-thaw cycle can still retain the basic structure,indicating that the freeze-thaw treatment can protect the internal organization morphology of the samples during heating. |
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