RECENT ADVANCES IN THE FREEZE-DRYING OF FOOD PRODUCTS

Food spoilage is caused by microbial growth or by chemical and physical changes, all of which affect the taste, texture, and safety of food.Temperature-Based PreservationRefrigeration at 0–4 °C slows microbial growth and enzyme activity, making it ideal for short-term storage. However, certain spoilage organisms—such as psychrotrophs like Listeria monocytogenes—can still proliferate at these temperatures. Freezing below -18 °C further slows biological processes by forming ice crystals, which...

Conventional electron microscopy (EM) involves dehydration, fixation, and staining of biological samples, which distorts the native state of biological molecules and results in several artifacts. Also, the high-energy electron beam damages the sample and makes it difficult to obtain high-resolution images. These issues can be addressed using cryo-EM, which uses frozen samples and gentler electron beams. The technique was developed by Jacques Dubochet, Joachim Frank, and Richard Henderson, for...

Food spoilage results from microbial growth, enzymatic activity, and environmental factors that gradually degrade the sensory, nutritional, and safety qualities of food. Preservation techniques aim to slow or halt these processes to extend shelf life and maintain product quality.A key concept in food microbiology is the microbial growth curve, which includes four phases: lag, exponential (log), stationary, and death. During the lag phase, bacteria adjust to their environment without significant...

Sublimation is the direct transformation of a solid to a gaseous state. For instance, at standard pressure and room temperature, solid carbon dioxide sublimes to gaseous carbon dioxide. The phase diagram depicts the conditions required for sublimation. This process occurs at the solid-gas phase boundary and is not observed above the triple point of the substance. The reverse of sublimation is called deposition, where a gaseous substance condenses directly into a solid. Sublimation and...