Date

2022-7

Author

Baydemir, Seçil

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Electrical household and similar cooling and freezing appliance manufacturers are continuously seeking ways to improve properties of their products. To design such appliances and obtain generalized and standardized results, developing test methods using food simulants has been a new strategy. Drip loss is an important problem experienced by the consumers during thawing of meat and refrigerator manufacturers try to design appliances to minimize this problem. Food simulants are used to mimic the cooling and freezing responses of foods during thawing and quick freezing. In this study, different food simulants for ‘drip loss’ were developed by using different hydrocolloids such as corn starch (10%, 15%, 20%), curdlan (3%), agar (2%, 3% and 4%) and methylcellulose (5%). During freeze-thaw cycle, food simulants along with ‘real foods’ (sirloin and chicken breast) were stored at two different temperatures (-18oC and -27oC) for 20 h and thawed at room temperature for 4 h. For characterization of the food simulants, total drip loss, hardness, FT temperature cycle, water holding capacity (WHC), NMR and scanning electron microscopy (SEM) measurements were conducted. To observe how water distribution changed, all measurements were conducted before and after FT cycle. Total drip loss of real food samples was also measured to compare with food simulants throughout thawing process. There were significant differences in drip loss rates for both curdlan-based food and methyl cellulose-based simulants frozen at two different temperatures (p<0.05). According to NMR analysis, curdlan-based samples with the lowest concentration had highest T2 values before FT cycle. It was observed that these samples also had the highest total drip loss percentage after FT cycle. Moreover, total drip loss (%) was observed to be positively correlated with spin-spin (T2) relaxation times before FT cycle (r= 0.844, p<0.05). After FT cycle, there was an increase in hardness values of curdlan-based food simulants while there was a decrease in methyl cellulose-based ones. SEM images showed that the addition of secondary polysaccharide with different concentration levels to methylcellulose-based and curdlan-based food simulants affected the microstructures of hydrogel. Home appliances manufacturers should develop test methods with standard artificial materials, which are food simulants, to measure the freezing performance of their products. Food simulants formulated and characterized in this study can be used in the design of freezer systems.

Subject Keywords

Refrigeration, Freezing, Food Simulants, Drip Loss, NMR Relaxometry

URI

https://hdl.handle.net/11511/98146

Collections

Graduate School of Natural and Applied Sciences, Thesis