Research on Optimization of Sweet Duck by Sous-vide Cooking (Part One)
Abstract: To promote the application of sous-vide cooking in the production process of sweet duck, this study was based on the traditional cooking methods of sweet duck, combined with modern low-temperature cooking, and optimized its cooking method through single-factor experiments and orthogonal experiments. The optimal process parameters for low-temperature cooking of sweet duck were finally determined. The slow cooking temperature was 75°C, the slow cooking time 50 minutes, the frying temperature 150°C, and the frying time 1.0 minutes. This study not only provides a theoretical reference for cooking sweet duck at a low temperature, but also provides a reference for the application of low-temperature cooking in cooking other food.
Sweet duck is a traditional delicacy in Leshan City, Sichuan Province. It is marinated and then fried. The sweet duck has a bright red color, tender meat, crispy and slightly sweet skin, and is very popular among consumers. The traditional sweet duck is heated and braised. This method can make it crispy, soft and palatable, but it will greatly damage the aroma and tenderness of the duck. Choosing a suitable cooking method to further improve the duck has become an urgent problem to be solved in manufacturing sweet duck. Sous-vide cooking is a relatively popular cooking method in recent years. It can preserve the taste of the ingredients to the greatest extent, without destroying the color and nutrients of the ingredients, minimize the weight loss of the food in the heating process, and improve the taste of the meat. This technology can effectively solve the problems existing in the production of traditional sweet duck. Applying the sous-vide cooking to the production of sweet duck to prepare a new type of sweet duck can not only enrich the variety of sweet duck, but also satisfy consumers' demand for new tastes.
The sweet duck was the research object in this article. The traditional process characteristics were analyzed. The differences between the sweet duck produced by the traditional method and the sous-vide cooking were analyzed by combining the sous-vide cooking technology and adopting single-factor experiment and orthogonal experiment
1. Materials and methods
1.1 Ingredients
Raw duck and salad oil purchased from Wal-Mart, brine purchased from Leshan Fuluwei Luwei Processing Factory, crispy syrup prepared by us, magnesium oxide and hydrochloric acid made in China
1.2 Instruments and equipment
CT050P117W Low-temperature Slow Cooking Equipment, Vacuum Sealers, TG-16W-I Centrifuges, PWN125DZH Electronic scales, S8156X constant temperature water bath box, ZP100L electric fryers. Other equipment is provided by the Food Science Laboratory of Lingnan Normal University.
1.3 Steps of making sweet duck
1.3.1 Preparation of traditional sweet duck
Remove the internal organs of the raw duck; wash the whole duck, and put it into a centrifuge for centrifugal dehydration. Put the duck in the brine to cook for 50 minutes and then stop heating. Soak it for 1 hour, and drain it. Spray crispy syrup on the duck and dry it. Deep-fry the duck.
1.3.2 Preparation of Sous-vide sweet duck
Remove the internal organs of the raw duck. Wash the whole duck, and put it into a centrifuge for centrifugal dehydration. Put the duck and brine into a vacuum bag and seal them. Cook the duck at a low temperature. Spray the crispy syrup and let the duck dry. Deep-fry the duck.
1.4 Experimental Design
This study determined the basic process conditions based on the basic process conditions of the pre-experiment. The slow cooking temperature is 75℃, slow cooking time 55 minutes, frying temperature 145℃ and frying time 2 minutes. Single-factor experiment was carried out with sensory evaluation as an index. The variable values of each factor are as follows: the slow cooking temperatures are 65℃, 70℃, 75℃, 80℃ and 85℃, slow cooking time 45 minutes, 50 minutes, 55 minutes, 60 minutes and 65 minutes, frying temperatures135℃, 140℃, 145℃, 150℃ and 155℃, frying time 1.0 min, 1.5 minutes, 2.0 minutes, 2.5 minutes and 3.0 minutes. The specific level factors are shown in Table 1.
Table 1 Factor level tables
Sweet duck is a traditional delicacy in Leshan City, Sichuan Province. It is marinated and then fried. The sweet duck has a bright red color, tender meat, crispy and slightly sweet skin, and is very popular among consumers. The traditional sweet duck is heated and braised. This method can make it crispy, soft and palatable, but it will greatly damage the aroma and tenderness of the duck. Choosing a suitable cooking method to further improve the duck has become an urgent problem to be solved in manufacturing sweet duck. Sous-vide cooking is a relatively popular cooking method in recent years. It can preserve the taste of the ingredients to the greatest extent, without destroying the color and nutrients of the ingredients, minimize the weight loss of the food in the heating process, and improve the taste of the meat. This technology can effectively solve the problems existing in the production of traditional sweet duck. Applying the sous-vide cooking to the production of sweet duck to prepare a new type of sweet duck can not only enrich the variety of sweet duck, but also satisfy consumers' demand for new tastes.
The sweet duck was the research object in this article. The traditional process characteristics were analyzed. The differences between the sweet duck produced by the traditional method and the sous-vide cooking were analyzed by combining the sous-vide cooking technology and adopting single-factor experiment and orthogonal experiment
1. Materials and methods
1.1 Ingredients
Raw duck and salad oil purchased from Wal-Mart, brine purchased from Leshan Fuluwei Luwei Processing Factory, crispy syrup prepared by us, magnesium oxide and hydrochloric acid made in China
1.2 Instruments and equipment
CT050P117W Low-temperature Slow Cooking Equipment, Vacuum Sealers, TG-16W-I Centrifuges, PWN125DZH Electronic scales, S8156X constant temperature water bath box, ZP100L electric fryers. Other equipment is provided by the Food Science Laboratory of Lingnan Normal University.
1.3 Steps of making sweet duck
1.3.1 Preparation of traditional sweet duck
Remove the internal organs of the raw duck; wash the whole duck, and put it into a centrifuge for centrifugal dehydration. Put the duck in the brine to cook for 50 minutes and then stop heating. Soak it for 1 hour, and drain it. Spray crispy syrup on the duck and dry it. Deep-fry the duck.
1.3.2 Preparation of Sous-vide sweet duck
Remove the internal organs of the raw duck. Wash the whole duck, and put it into a centrifuge for centrifugal dehydration. Put the duck and brine into a vacuum bag and seal them. Cook the duck at a low temperature. Spray the crispy syrup and let the duck dry. Deep-fry the duck.
1.4 Experimental Design
This study determined the basic process conditions based on the basic process conditions of the pre-experiment. The slow cooking temperature is 75℃, slow cooking time 55 minutes, frying temperature 145℃ and frying time 2 minutes. Single-factor experiment was carried out with sensory evaluation as an index. The variable values of each factor are as follows: the slow cooking temperatures are 65℃, 70℃, 75℃, 80℃ and 85℃, slow cooking time 45 minutes, 50 minutes, 55 minutes, 60 minutes and 65 minutes, frying temperatures135℃, 140℃, 145℃, 150℃ and 155℃, frying time 1.0 min, 1.5 minutes, 2.0 minutes, 2.5 minutes and 3.0 minutes. The specific level factors are shown in Table 1.
Table 1 Factor level tables
| Levels | A Slow cook temperatures/℃ | B Slow cook time/minutes | C Fry temperatures/℃ | D Fry time/minutes |
| 1 | 70 | 50 | 145 | 1.0 |
| 2 | 75 | 55 | 150 | 1.5 |
| 3 | 80 | 60 | 155 | 2.0 |
1.5 Sensory evaluations
Choose 15 sensory evaluation personnel with professional backgrounds related to cooking whose ages are 20 to 25 to analyze the quality of sweet duck prepared at low temperatures by descriptive methods before sensory evaluations. They evaluate the duck by its taste, texture and aroma. Each sample number is evaluated 3 times, and the average value is the final result. The specific sensory evaluation standards are shown in Table 2.
Table 2 Sensory evaluation criteria
| Sensory descriptions | Sensory evaluation criteria | Scores | |||
| Color (25%) | Aroma (25%) | Taste (25%) | Texture states (25%) | ||
| Excellent | Red and bright | Excellent natural salty and no peculiar smell | Good aftertaste | The meat is good with crispy skin. | 21 to 25 |
| Good | Light red but acceptable | Excellent natural salty and no peculiar smell | Good aftertaste | The meat is good with crispy skin. | 15 to 20 |
| Average | Light red with little other colors | Average natural salty and little peculiar smell | Average aftertaste | The meat is average with poor crispy skin. | 10 to 14 |
| Bad | Little red and uneven color | No natural salty and serious peculiar smell | Poor taste | The meat is rough without crispy skin. | 0 to 9 |
1.6 Determination of physical and chemical indicators
The weight of sweet duck was weighed before and after cooking, and the difference between before and after weight was divided by the weight before cooking to obtain the cooking loss rate; the determination of volatile base nitrogen (TVB-N) was based on the method of Tao Hu and others.
1.7 Data processing
Data statistics and graphing were carried out through Excel 2010.