Impact of processing temperature and duration on physicochemical attributes of thermosonicated chicken sausage

Introduction

Meat has consistently been the best source of protein. A large portion of the global population consumes frequently due to its enticing flavour and taste in addition to nutritional qualities. Along with micronutrients like niacin, vitamin b12, iron, zinc, selenium and amino acids that are necessary for human health. It also has an impressive amount of fat and carbohydrates that serve as an energy source [1,2] . The moisture content of poultry meat (70.09%) makes it a very nutrient dense food, protein (18.59%), ash (0.80%) and fat (6.0%). Minerals like iron and phosphorous, vitamins like niacin and riboflavin are abundant in poultry meat. It is a favourite food of both young people and elder due to its high biological value and ease of digestion [3] . Around the world, sausage is one of the most consumed foods [4] explained that fresh sausages are uncured and unheated meat products prepared from pork, beef, chicken, fish and fat with textures ranging from coarse to finely emulsified depending on local traditions. Meat becomes more palatable and easier to digest when it is cooked. A cooking method produces high quality meat product with pleasing texture and flavour is chosen by customers. For cooking of sausages, traditional cooking temperatures greater than 80⁰C have been utilized. The temperature and time at which meat is cooked affects its physical properties and overall quality. Meat's unique proteins become denatured when cooked altering the textures structural integrity of the meat. Despite the fact some of these procedures (like resistive and adiabatic heating during high pressure processing and pulsed electric field respectively) generate heat due to internal energy generation. They are termed non thermal as they control microorganisms without high temperatures, thus preserving the food flavour, colour and nutritional quality. Thermsonication uses heat and ultrasound shown to be more effective method of inactivating microorganisms than either method by itself. Ultrasound treatment caused microbial inactivation primarily due to generation of acoustic cavitation causing thinning of cell membranes, loss of selectivity and increased membrane permeability. During the cooling phase, confined heating and singlet electron transfer contributes to inactivation process [5] . Sausage was processed by using microwave and thermosonication methods [6] . Prototype sausage was heated at 80⁰C for varying lengths of time (10, 20, 30, and 40 minutes) using the ultrasonic bath set to 40kHz and a microwave with 400, 600 and 800 W of power. This was done contrast to the traditional method of heating (75⁰C for 15 minutes). The effects of microwaves and thermosonication on chemical, physical and microbiological characteristics of sausage samples as well as degree of consumer preference were examined using randomized design. As, a result the prototype sausage shelf life was increased and the meat quality was preserved under ideal thermosonication conditions of 80 ⁰C for 20 minutes. Commercial chicken sausage frankfurters prepared using ohmic heating at 45, 50 and 55 V and compared their colour, texture, moisture content and water activity with non-heated samples [7] . They reported that water activity decreased significantly at 50 V while, the hardness and shear force at this level were comparable to non-heated sausages.

German and gourmet sausages containing 40% and 65% raw meat irradiated at doses 2, 4, 6 and 8 kGy were examined and found higher doses (8 kGy) reduced colour, taste and odour scores, while lower doses (2 -4 kGy) better preserved sensory quality. Overall, lower levels of gamma irradiation were considered effective in reducing residual nitrite and enhancing shelf life of sausage.

Materials and Methods

The chicken meat was deboned, cleaned and washed thoroughly; excess water was removed as part of the preparation carried out. The meat was minced using an MADO Patron mincer, after salt, chilli powder, maida and chicken masala were added. Using a bowl chopper oil, egg and ginger garlic paste was blended into the mixture to form uniform sausage emulsion. This emulsion was filled into artificial casings with a mechanical filler and left to rest at 15 -18⁰C for 4 hours. The sausages were then stored at -18⁰C until further processing. Cooking was performed in a thermosonicator by using 5 liters water, varying temperature and time as per Table 1. Following the procedure prescribed with slight modifications [8] . After cooking the samples were removed from thermosonicator bath. Cooking loss, product yield and pH were determined.

Cooking loss

Weighing the chicken sausage before and after cooking is the most common method. The difference between the raw weight and cooked weight, which is frequently given as a percentage, is then used to compute cooking loss [9] .

Product yield

Product yield was determined by measuring the weight of the sample before and after cooking using the following equation and the results were reported as percentages [10,11] .

pH

The pH was determined using a digital pH meter [12] .

Statistical analysis

All tests were performed at least three times for each experimental condition and mean values were reported, statistical analysis was performed by using the Statistical Package for the Social Sciences (version 25) to calculate the average and standard deviation. When Duncan's multiple range test method was used, the significance test (p<0.005) was carried out through multiple tests.

Results and discussion

Cooking loss

The cooking loss values of thermosonicated chicken sausages processed under varying time and temperature condition are presented in Table 2. Specifically, higher cooking temperatures or longer processing times resulted in increased cooking loss. This increased progressively with rising processing temperature and extended treatment time. The lowest cooking loss (0.354±0.002%) was observed at 61⁰C for 25 minutes, while the highest value (4.470±.014%) occurred at 70⁰C for 40 minutes. This trend can be attributed to the greater denaturation and shrinkage of myofibrillar proteins at higher temperatures, which results in reduced water holding capacity and increased exudation of moisture and soluble nutrients during cooking. Prolonged exposure to heat promotes connective tissue contraction, further enhancing fluid loss from the meat matrix. Cooking loss (P ≤ 0.005) is highly significant. Cooking loss was significantly increased with increasing temperature and time.

Product yield

The result of product yield of thermosonicated chicken sausage and control was summarized in Table 2. With different time and temperature. Product yield of thermosonicated chicken sausages was significantly reduced with processing temperature and time. Higher yields (99.6%) were obtained at lower temperatures (61 -64 ⁰C) and shorter time duration (25 -30 minutes) indicating better moisture retention. As both temperature and time increased, product yield decreased progressively reaching a minimum of 93.53% at 70 ⁰C for 40 minutes. This reduction is attributed to enhanced protein denaturation and moisture loss under prolonged thermal and ultrasonic treatment.

The ultrasound assisted processing temperatures exceeding 65 ⁰C significantly decreases product yield in chicken sausages due to intensified protein unfolding and fibre contraction [13] .

Similarly, The prolonged ultrasound treatment combined with heat increases drip loss in pork batters confirming the role of treatment duration and temperature in compromising product yield.

Ultrasound accelerates protein gelation but excessive exposure causes protein aggregation and shrinkage impairing the meat matrix's ability to retain water and fat [14] . Whereas, processing intensity is critical to optimize microbial safety without detrimentally affecting product yield [15] .

pH

The result of pH of thermosonicated chicken sausage is summarized in Table 2. The pH values of thermosonicated chicken sausages ranged from 6.12 to 6.67 across different processing times and temperatures. The pH values are highly significant (P ≤ 0.005) was observed in pH variation with respect to time and temperature indicating that thermosonication under the studied conditions did not significantly alter the overall acidity or alkalinity of the product. Slight fluctuations in pH could be attributed to protein denaturation and the release of acidic or basic groups during heat and ultrasound treatment can modify the muscle matrix microenvironment [16] . Importantly pH values remained within the typical range for fresh meat products (generally 5.8 -6.8) suggesting that processing did not induce spoilage or undesirable chemical changes [17] .

Conclusion

The application of thermosonication as an alternative cooking method for chicken sausage significantly reduces cooking loss while enhancing product yield. This advanced technique effectively preserves moisture and minimizes the loss of fats and nutrients, thereby improving the overall quality and nutritional value of the final product. Incorporating such innovative cooking technologies in sausage production not only offers economic advantages through higher yield but also elevates consumer satisfaction by delivering a superior product. These findings highlight the potential of modern processing methods to optimize meat product quality and efficiency in the food industry.

Acknowledgement

We are also deeply grateful to College of Food and Dairy Technology, Chennai -600 052. We thank faculty and staff particularly for providing us with the resources and environment conductive to our research and development efforts.

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