<正>近些年来,由于冷冻食品的冷库库容量的大幅增加加上消费者对冷冻食品的认可(主要是营养、卫生、方便)使冷冻食品市场呈现一种蓬勃的趋势。全球经济的发展、社会生活节奏和家庭型态的改变以及食品

The effects of mixing and resting on the physicochemical properties of doughs prepared with strong and weak hard wheat flours were investigated, specifically concerning aspects related to their rheological behavior and molecular mobility. Small deformation dynamic tests showed that, during the initial resting period, the complex modulus G* decreased and phase angle decreased for undermixed dough, whereas overmixed dough showed opposite trends. G* values for optimally mixed dough did not vary during the resting period investigated. This was more obvious for the strong dough. Large deformation tests more clearly showed differences among optimal, under-, and overmixed dough, and also between doughs prepared with strong and weak flour. Optimally mixed dough exhibited the highest peak stress and strain for both samples. In addition, the peak stress of dough prepared with the strong flour was higher than that of dough prepared with weak flour. Inconsistent results between small and large deformation tests implied that small and large deformation tests reflected different structural aspects of dough. NMR measurements were performed to estimate the relaxation properties of the sample upon resting. Decreased water mobility during resting, indicated by decreasing T(1) relaxation time, was possibly attributed to increasing molecular interactions caused by continued hydration. Evidence of additional molecular interactions created by mixing was also observed.

Freezing Principles Freezing Processes: Physical Aspects Principles of Freeze-Concentration and Freeze-Drying Principles of Frozen Storage Frozen Food Packaging Frozen Food Characteristics Frozen Food Components and Chemical Reactions Flavor of Frozen Foods Food Sensory Attributes Texture in Frozen Foods Frozen Meat and Poultry Frozen Muscle Foods: Principles, Quality, and Shelf Life Operational Processes for Frozen Red Meat Frozen Meat: Processing Equipment Frozen Meat: Quality and Shelf Life Chemical and Physical Aspects of Color in Frozen Muscle-Based Foods Frozen Meat: Packaging and Quality Control Frozen Poultry: Process Flow, Equipment, Quality, and Packaging Frozen Seafoods Freezing Seafood and Seafood Products Principles and Applications Freezing Finfish Freezing Shellfish Freezing Secondary Seafood Products Frozen Seafood Safety and HACCP Frozen Seafood: Product Descriptions Frozen Vegetables Frozen Vegetables: Product Descriptions Quality Control in Frozen Vegetables Production, Freezing, and Storage of Tomato Sauces and Slices Frozen French Fried Potatoes and Quality Assurance Frozen Peas: Standard and Grade Frozen Fruits and Fruit Products Frozen Fruits and Fruit Juices: Product Description Frozen Guava and Papaya Products Frozen Citrus Juices Frozen Desserts, Frozen Dough, and Microwavable Frozen Foods Ice Cream and Frozen Desserts Effect of Freezing on Dough Ingredients Microwavable Frozen Food or Meals Frozen Foods Safety Considerations Safety of Frozen Foods Frozen Food Plants: Safety and Inspection Frozen Dessert Processing: Quality, Safety, and Risk Analysis Frozen Foods and Enforcement Activities Appendix A FDA Standard for Frozen Vegetables: 21 CFR 158. Definitions: 21 CFR 158.3 FDA Standard for Frozen Vegetables: 21 CFR 158. Frozen Peas: 21 CFR 158.170 Appendix B Frozen Dessert Processing: Quality, Safety, and Risk Analysis. Special Operations Index

Ultrasound technology was used to analyse the freezing behaviour of orange juice. The ultrasonic properties of orange juice, specifically velocity and attenuation coefficient, were characterised as the temperature was decreased from 20 to -50degreesC. The results were compared with NMR free induction decay data and correlated with the amount of unfrozen water present in the frozen sample. The velocities of longitudinal waves (P-wave) and shear waves (S-wave) in frozen orange juice were measured, yielding values of around 4000 and 2000 m s(-1) respectively. They were related to the amount of unfrozen water in the frozen sample. The elastic moduli of the samples at different temperatures were obtained from the measured ultrasonic velocities. Significant changes in the attenuation of the ultrasonic waves propagated through the frozen sample were observed as a result of ice nucleation and growth. Information about the spectral behaviour of the ultrasound signal was obtained by means of wavelet analysis. The analysis provided a direct measure of the spectral content of the ultrasonic waves over time and showed the variation in the ultrasonic velocity dispersion with temperature. Significant velocity dispersions occurred for frequencies less than 1 MHz. (C) 2004 Society of Chemical Industry.