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Contact Us

Head of Institute: Prof. Oren Tirosh

Administrative manager: Rakefet Kalev

Office Address:
Institute of Biochemistry, Food Science and Nutrition,
Robert H. Smith Faculty of Agriculture, Food and Environment,
The Hebrew University of Jerusalem, 
Herzl 229, Rehovot 7610001, ISRAEL

Tel: +972 - (0)8-9489385
Fax: +972 - (0)8-9363208
Email Address: rakefetk@savion.huji.ac.il

Research Projects

Protective coatings for foods, agricultural products and cells           Temperature-stable liquid-core capsules     
Cellular dry macro-capsules           Sponges          Composite cellular carriers      
Biomaterials as carriers of denitrification bacteria for water treatment in aquariums

Protective coatings for foods, agricultural products and cells

For many years we have studied coatings of fruits, vegetables, cheeses and meat products. We observed how the deterioration of mushrooms, fresh and dry garlic and flower corms was slowed by immediately coating them with edible biodegradable films. Studying the physical properties of the food surface, such as roughness and porosity (introducing into the food area apparatuses borrowed from the car industry, such as a roughness tester, and designing the first glossmeter for curved surfaces), preparing 3D maps of those surfaces (by using software and methods from topography), and understanding the interactions between the coating solution and the food, how to compose a coating solution and change its properties, such as wettability and penetration, and the best way to dry it, have all contributed towards preparing tailor-made coatings. A coating of transparent dried film should not alter the price per unit weight of the product, and by improving its gloss properties, can improve its market value. In our recent studies we have tried to deliberately introduce disturbances into the wax coatings to improve their functionality.

A. Nussinovitch (2000). Gums for coatings and adhesives. In: Handbook of Hydrocolloids. Phillips, G. and Williams, P. (Eds.) CRC, Woodhead Publishing Limited, Cambridge, England, pp. 347-367.

V. Hershko and A. Nussinovitch (1998). The behavior of hydrocolloid coatings on vegetative material. Biotechnology Progress, 14, 756-765.

S. Chen and A. Nussinovitch (2000). Galactomannans in disturbances of structured wax-hydrocolloid based coatings of citrus (easy peelers). Food Hydrocolloids, 14, 561-568.

We began with edible gum-based coatings for foods, and later developed more complex coatings for frog embryos and oocytes. The difference between coating and entrapping is the thickness of the coating layer, being very thin in the former, thick in the latter. Coatings were prepared to constitute a barrier to microbial contamination, to postpone embryo hatch to more developed stages, to slow embryo development without harming its biological activity, to serve as an energy-accumulating lens (for preserving eggs and embryos in cold solutions) and to facilitate embryo survival under harsh conditions, such as exposure to hazardous materials and mechanical damage. These studies could serve in the future as a springboard for successful transplantation and preservation studies with human embryos.

A. Nussinovitch, V. Hershko and H.D. Rabinowitch. Protective coatings for food and agricultural products, methods for producing same and products coated by same. U.S. patents #6,299,915 and #6,068,867 and Israeli patent #111495.

N. Kampf, C. Zohar and A. Nussinovitch (2000). Hydrocolloid coating of Xenopus laevis embryos. Biotechnology Progress, 16, 480-487.

Temperature-stable liquid-core capsules

Novel products are composed of a liquid core (fluid) coated by a hydrocolloid membrane with different properties, sizes and compositions can mimic grapes, different berries, caviar, and the like. The membrane can be tailored to different thicknesses and thermal stabilities. While their use in foods is obvious, enzymes and cells can also be included within the droplet and used for continuous fermentation, possible transplantation, slow release and other biotechnological processes.

A. Nussinovitch. Temperature-stable liquid cells. U.S. patent #6,099,876.

Cellular dry macro-capsules

Hydrocolloid capsules are spongy moieties that can include active materials, microorganisms and/or enzymes within their cellular matrix and withstand UV radiation. Produced or embedded materials can be diffused in a controlled slow-release process. The macro-capsules are inexpensive, can easily be tailored for full control of shape and size, are easily formulated, applied and modified, and are compatible with bioactive agents. In addition to slow release of fungicides, germicides, and growth factors, macro-capsules can be produced for animal feed, as vitamin carriers, for biotechnological applications such as denitrification of water, for snack foods and for processes related to wine and the confectionery industry. For biological control, a special product, composed of hydrocolloids and including microorganisms or other biologically important materials such as chemicals and micronutrients, was developed. The resultant product can be dispersed in the soil, in water, or in aqueous solutions of fertilizers, including drip-irrigation and spraying.

C. Zohar (Perez), E. Ritte, L. Chernin, I. Chet and A. Nussinovitch (2002). Entrapment of Pantoae agglomerans by cellular dried alginate-based carriers. Biotechnol. Prog. 18, 1133-1140.

Sponges

Hydrocolloids are combined and processed in many different patented ways to produce sponges with no nutritional value that are dry, with different degrees of dryness, porosity, taste, composition and color. Hydrocolloid sponges are compressible and can absorb liquids. The sponges are excellent matrices for the inclusion of proteins, carbohydrates, vitamins, microorganisms and many other compounds. They can serve as the basis for high- or low-calorie foods. In their compressed form, they can be an excellent potential food source in the air and space industry. The sponges can also be specifically designed to target a wide range of markets. With their high liquid-absorbing properties and high degree of compressibility, the sponges can be adapted for use as medicinal bandages, biodegradable diapers and hygienic pads.

A. Nussinovitch. Sponges from hydrocolloids and method for their production. Israeli patent #104,441 and US patent #6,589,328.

D. Rassis, I.S. Saguy and A. Nussinovitch (1998). Physical properties of alginate-starch cellular sponges. J. Agric. and Food Chem., 46 (8), 2981-2987.

Composite cellular carriers

Further developments in sponge technology have led to the production of complex cellular solids. These complexes are composed of a continuous matrix embedded with spherical particles of different sizes and compositions. The particles and matrix can be composed of different hydrocolloids. In general, these complexes can be used as novel carriers for slow release, immobilization agents, and food products and packaging materials.

Biomaterials as carriers of denitrification bacteria for water treatment in aquariums

With the booming interest in aquariums as a hobby and, consequently, the introduction of new exotic ornamental fish species, higher water-quality standards are required for those aquariums. Some fish species are unable to propagate or grow in water containing high nitrate levels, and those levels stimulate undesirable algal growth on the aquarium walls. Today, only a limited number of commercial biofiltration systems adapted to nitrate removal from aquariums are available. Moreover, problems are often encountered with those few commercially available filters, and there is therefore a need for denitrifying filters that are easy to operate and instantly and rapidly remove nitrate from aquariums. We designed novel beads which have potential applications in water-purification systems for aquariums. Denitrifying bacteria immobilized in a matrix composed of single or complex biopolymers and other ingredients were employed as reducing agents in the conversion of nitrate to nitrogen gas. These unique beads enable the incorporation of the bacteria at a high concentration and stability. Denitrifying activity was sustained over an extended period of time with limited loss of carrier texture. Pilot studies employing the beads have been successfully carried out in commercial-size aquariums.

J. van Rijn, A. Nussinovitch and Y. Aboutbul. Means and process for nitrate removal. U.S. patent #6,297,033, Israeli patent application 117783, European patent # 97914533.1.

Y. Tal, J. van Rijn and A. Nussinovitch (1997). Improvement of structural and mechanical properties of denitrifying alginate beads by freeze-drying. Biotechnology Progress, 13 (6), 788-793.

Y. Tal, A. Nussinovitch and J. van Rijn (2003). Nitrate removal in aquariums by immobilized denitrifiers. Biotechnol. Prog. 19 (3), 1019-1021.