INVESTIGATION OF SANITARY-HYGIENIC CHARACTERISTICS OF MULTILAYER POLYMER FILMS USED FOR VACUUM PACKAGING MODIFIED BY NATIVE ANTIMICROBIAL COMPONENTS

Введение Развитие упаковочной отрасли привело к повышению роли упаковки в современном производстве продуктов питания. Тип и санитарное состояние упаковки признаны одними из основных факторов, влияющих на качество и продолжительность хранения расфасованной молочной продукции. Помимо обеспечения сохранности продукта от внешних загрязнений и привлекательного внешнего вида к современной упаковке предъявляются требования по активной защите содержимого. При хранении большинства продуктов питания в происходящих с ними химических и микробиологических изменениях основную роль играет совокупность нескольких факторов: кислород, свет и температура. Наиболее доступным и распространенным приемом устранения порчи продуктов под влиянием кислорода называют упаковывание, при котором происходит вакуумное удаление кислорода. Постоянное расширение ассортимента пищевых продуктов, а также общая тенденция увеличения их сроков годности предъявляют особые требования к используемым упаковочным материалам и изготовленной их них таре. Химический состав и структура упаковочных материалов определяют не только безопасность их использования при контакте с продуктом, но и обеспечивают комплекс требуемых функциональных свойств [1, 2]. Одной из существенных проблем является подавление роста нежелательной поверхностной микрофлоры на продуктах питания. Данную проблему можно решить за счет использования сырьевых компонентов повышенной микробиологической чистоты, применением определенных стабилизирующих добавок в продуктах, применением метода асептической расфасовки. Перспективно направление, все более активно Fedotova O.B., Myalenko D.M. All-Russian Dairy Research Institute, Moscow, Russia INVESTIGATION OF SANITARY-HYGIENIC CHARACTERISTICS OF MULTILAYER POLYMER FILMS USED FOR VACUUM PACKAGING MODIFIED BY NATIVE ANTIMICROBIAL COMPONENTS


Introduction
Development of the packaging branch resulted in improving the level of packaging in the field of food products manufacture.Type and sanitary conditions of packaging are one of the basic factors influencing the packed milk products quality and storage life.Besides of the product safety guarantee against air pollution and attractive appearance modern packaging requires active protection of its content.
During the majority of food products storage chemical and microbiological changers take place due to the complex of the following factors: oxygen, light and temperature.The most available and wide-spread method used to eliminate the products contamination under the influence of oxygen is packaging when oxygen removal takes place.The constant expansion of food products assortment as well current tendency to improve their storage life forces to make special demands to applied packaging materials and containers manufactured from them.The chemical composition and packaging materials structure specify not only safety of their usage during contact with this product but provide the complex of the required functional properties [1,2].
One of the main problems is inhibition of undesirable surface microflora growth on food products.The mentioned problem can be tackled by usage of raw materials components with high microbial purity, usage of the specific stabilizing additives in the products and aseptic packaging method.The perspective direction being very popular nowadays abroad is usage of so called active packaging i.e. packaging influencing directly the product [3,4].
desirable microflora on the packaging surface during possible secondary contamination.
The experiment shows that polymer film materials posses the important perspective for vacuum packaging where polyamide representing inert material is used as the barrier layer being harmless for contact with food products in our country.Bags from the mentioned material possesses the required penetrability relating to carbon dioxide and simultaneously don't leak oxygen vapors.It is important that on the production stage intermediates of these bags are treated at high temperature and delivered to the further stages in sterilized form.It is influenced very positively on storage life of these products in such bags.[4].

Materials and methods
FGBNU «VNIMI» is carrying out the works covering the creation of innovative multilayer polymer films where inner layer contacting with food product is modified by native antimicrobial components.
Birch bark extract has been chosen as the antimicrobial component where betulin (betulenol C 36 H 60 O 3 ) is the basic active substance in the concentration not less than 70%.
Whereas introduction of any components improving or adding new properties to packing materials can result in impairing of polymer materials quality we studied sanitary-hygienic characteristics of multilayer polymer films where inner layer was modified by native antimicrobial components in different concentration.
The patterns of modified polymer films have slightly goldish-beige tint distributed evenly over the product surface.There are no crazings, punctures and visual defects on the surface.Seemingly the product corresponds to TR TC 005/2011 requirements «About Packaging Material Safety».Aqueous extracts from the studied patterns at all temperatures and exposure periods contain now slime or sediment and don't change the color.Increasing the temperature results in smell intensification of extracts from test film samples comparing to the extracts from control samples.
In all cases smell evaluation doesn't exceed 1 point that corresponds to Rospotrebnadzor requirements to polymer materials contacting with food products and technical regulations of customs union (Figure 1).

Results and discussion
Studies aimed at determination of formaldehyde in aqueous extracts showed that it is absent in all samples.It confirms the fact that presence of the extract -(1% concentration) in the analyzed samples doesn't deteriorate the material sanitary-hygienic characteristics The carried out tests showed that increase of extract concentration in the material results in increase of brominating substances in aqueous extracts (Figure 2).It can be connected with the presence of double bond in betulinol structure.However the determined total amount of organic matters contacting with bromine is insignificant that makes it possible to consider the material test samples acceptable for usage in food industry.

Studying of the surface state and the tested samples changes
The working hypothesis accepted as the basis shows that the extract antimicrobial matters extracting gradually in the process of storage from the packing material are diffused on the surface for active impact on microorganisms on surface spoiling.In the frame of this work aimed at confirming of such hypothesis the decision to carry out series of experiments to evaluate the state of samples material surface modified by the extract was made.
As visual confirmation of extract presence on the packaging material surface contacting potentially with the product the pictures of the film samples surface under a microscope with 300 times increase (Figure 3).
The received micrographs showed the structure change on polymer films surface: with the increase of extract concentration on extra enclosures of pale yellow microflakes are distinctly visible on the material surface.It may be connected with intensification of the extract antimicrobial substances migration to the surface.
In cooperation with our colleagues the infrared spectra of the developed test multilayer films modified by native antimicrobial components have been realized.
The quality analysis of the samples molecular structure using infrared microscopy of Bruker company has been carried out.Infrared spectrum of films samples with different amount of antimicrobial additive was registered for the purpose.The absorption lines of bitulin additive in the area of 880 cm -1 (correspond to deformation of C-H in trisubstituted benzene derivatives ) and C-O group in betulin molecule appeared on the test samples.(Figure 4 & Figure 5).
The derived infrared spectra confirm the obtained test results and indicate that introduction of native antimicrobial modifier in the concentration range from 0 to 2,0% has no negative impact on sanitary-hygienic characteristics of the tested multilayer polymer films.

Conclusions
The obtained results of the complex studies show that according to these results the tested film materials samples correspond to the requirements of the customs union TR CU 005/2011 «About Package Safety» and can be recommended for usage in meat, dairy and food branches.

Acknowledgement
We are grateful to our colleagues from FGBNU « VNIITeK» Tarasyuk V.T. and «Bruker» company Repnikov V.V. for their assistance in carrying out of spectral analysis of the developed multilayer films test samples modified by native antimicrobial components.