Développements technologiques nouveaux en lyophilisation

Wolff, E.; Gibert, H.

doi:10.1016/0260-8774(88)90057-x

Cited by 31 publications

(9 citation statements)

References 8 publications

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“…On an industrial scale, Flink (1977) considered that the running cost of freeze-drying processes is 4-5 times higher than that of the spray-drying technique. Similar energy consumption tendency levels were found by Wolff & Gibert (1988) and by Roux (1994). The use of freeze-drying in food industries is therefore restricted to high added-value products such as coffee and tea, ingredients for ready-to-eat foods (vegetables, pasta, meat, fish, etc.…”

Section: Introductionsupporting

confidence: 87%

Process–quality optimization of the vacuum freeze‐drying of apple slices by the response surface method

Hammami

Rene

Marin

1999

Int J of Food Sci Tech

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Summary Working pressure (P) and heating plate temperature (T) were considered to be the most important factors affecting the kinetics of the freeze‐drying operation for apple slices as well as the criteria of final product quality (appearance/shape, colour, texture, rehydration ratio). Freeze‐drying experiments involving a thick layer of slices under different processing conditions were designed according to a central composite rotatable system with two factors (P, T). Results were analysed by response surface methodology (RSM). By superimposing all quality criteria contour plots, the optimum levels of processing conditions yielding the best quality freeze‐dried apple slices were determined to be an operating pressure of 50 Pa, and a heating plate temperature of 55 °C. For a product loading of 17 kg m−2, the freeze‐drying time ranged from 48 to 50 h. The experimental values of the freeze‐drying time, appearance and colour of freeze‐dried apple slices obtained with these optimal conditions were very similar to those predicted by the corresponding second order polynomial model. The rehydration ratio of freeze‐dried apples was about 0.55 g g−1 of water removed and the texture loss of rehydrated apples was estimated to be more than 85%.

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Section: Introductionsupporting

confidence: 87%

Process–quality optimization of the vacuum freeze‐drying of apple slices by the response surface method

Hammami

Rene

Marin

1999

Int J of Food Sci Tech

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“…Although discovered at the end of the 1950s [123], this freeze-drying process started to pick up scientific interest mainly in the mid 1980s. Due to the lack of vacuum use, the cut off was approximately 34% as compared to vacuum freeze-drying [124]. However, drying times increased 1 to 3 times since the use of atmospheric pressure turns the control of the process from heat to mass transfer, which makes the kinetic extremely slow [3].…”

Section: Pretreatments and Process Intensificationmentioning

confidence: 99%

Freeze-Drying of Plant-Based Foods

Bhatta

Janežić

Ratti

2020

Foods

222

103

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Vacuum freeze-drying of biological materials is one of the best methods of water removal, with final products of highest quality. The solid state of water during freeze-drying protects the primary structure and the shape of the products with minimal volume reduction. In addition, the lower temperatures in the process allow maximal nutrient and bioactive compound retention. This technique has been successfully applied to diverse biological materials, such as meats, coffee, juices, dairy products, cells, and bacteria, and is standard practice for penicillin, hormones, blood plasma, vitamin preparations, etc. Despite its many advantages, having four to ten times more energy requirements than regular hot air drying, freeze-drying has always been recognized as the most expensive process for manufacturing a dehydrated product. The application of the freeze-drying process to plant-based foods has been traditionally dedicated to the production of space shuttle goods, military or extreme-sport foodstuffs, and specialty foods such as coffee or spices. Recently, the market for ‘natural’ and ‘organic’ products is, however, strongly growing as well as the consumer’s demand for foods with minimal processing and high quality. From this perspective, the market for freeze-dried plant-based foods is not only increasing but also diversifying. Freeze-dried fruits and vegetables chunks, pieces, or slices are nowadays majorly used in a wide range of food products such as confectionaries, morning cereals, soups, bakeries, meal boxes, etc. Instant drinks are prepared out of freeze-dried tea, coffee, or even from maple syrup enriched with polyphenol concentrated extracts from trees. The possibilities are endless. In this review, the application of freeze-drying to transform plant-based foods was analyzed, based on the recent research publications on the subject and personal unpublished data. The review is structured around the following related topics: latest applications of freeze-drying to plant-based foods, specific technological problems that could be found when freeze-drying such products (i.e., presence of cuticle; high sugar or lipid concentration), pretreatments and intensification technologies employed in freeze-drying of plant-based foods, and quality issues of these freeze-dried products.

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“…Freeze-drying is a common method for producing stable food products, with the highest quality and long shelf life. This process is largely used to dry thermal sensitive products such as antibiotics, bacteria, pharmaceutical products, food ingredients or those with high value-added such as coffee, herbs or nutraceuticals (Wolff and Gibert 1988;Palmfeldt et al 2003). However, the energy consumption to maintain vacuum during the long processing times involved in freeze-drying is highly expensive, which constitutes the main disadvantage of this technique.…”

Section: Introductionmentioning

confidence: 99%

Foam‐mat Freeze‐drying of Apple Juice Part 2: Stability of Dry Products During Storage

Raharitsifa¹,

Ratti

2010

J Food Process Engineering

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Sorption isotherms at 5, 20 and 35C and glass transition temperature as a function of water content were evaluated for foamed (3% egg white and 1% methylcellulose) and nonfoamed freeze‐dried apple juice by using the static gravimetric method and differential scanning calorimetry, respectively. Equilibrium isotherms were fitted to the Guggenheim–Anderson–de Boer equation, whereas glass transition temperature to the Gordon–Taylor model. After freeze‐drying at 20C during 48 h, the dry products were stored at different temperatures (5 and 20C) under ambient conditions or vacuum. The nutritional, physical and structural properties were assessed before and at the end of the freeze‐drying process and after storage by determining vitamin C content, solubility, color and microstructure. Freeze‐dried nonfoamed juice retained more vitamin C and was more soluble than foamed products after freeze‐drying. However, foam‐mat juice powders presented higher stability during storage at 20C, which agreed with their higher values of glass transition temperature. Freeze‐dried juice stored at this temperature collapsed showing a decrease in solubility and a marked color change. PRACTICAL APPLICATIONS Quality of dry products depends largely on how they are stored (relative humidity, temperature, presence of light and vacuum). Degradation of flavor, color and texture occur under adverse storage conditions. Nutritional compounds such as vitamins or unsaturated fats could also be negatively affected because of oxidation reactions, which could be a function of the dehydration method or the pretreatment used to manufacture the dry product. The determination stability and quality degradation of foamed and nonfoamed apple juice products during freeze‐drying and storage of the dry products will complete the evaluation of foaming as a potential pretreatment for freeze‐drying.

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Développements technologiques nouveaux en lyophilisation

Cited by 31 publications

References 8 publications

Process–quality optimization of the vacuum freeze‐drying of apple slices by the response surface method

Process–quality optimization of the vacuum freeze‐drying of apple slices by the response surface method

Freeze-Drying of Plant-Based Foods

Foam‐mat Freeze‐drying of Apple Juice Part 2: Stability of Dry Products During Storage

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