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A COMPARATIVE CHARACTERIZATION OF PHYSICO-CHEMICAL PROPERTIES OF THE RAW DRIED SAUSAGES PRODUCED WITH
STARTER CULTURES Grad^rska D.N. (Republic of Bulgaria) Email: Gradinаrska543@scientifictext.ru
Gradinarska Dilyana Nikolaeva - PhD in Food Technologies, Chief Assistant, DEPARTMENT OF MEAT AND FISH TECHNOLOGY, TECHNOLOGICAL FACULTY, UNIVERSITY OF FOOD TECHNOLOGIES, PLOVDIV, REPUBLIC OF BULGARIA
Abstract: the main concern of food industry specialists nowadays is to guarantee public health by securing the consumption of salubrious food products with a high degree of innocuousness and a high nutritional value. The informed consumers prefer fresh meat products. Raw-dry sausages and salami fall into this category because they are well preserved for longer periods of time and for their specific flavor. The present study's aim was to determine the nitrite's content variation- nitrite is imperative for the reddish colour in meat and also for antimicrobial protection by using starter cultures of selected microorganisms, which, together with other components such as humidity, pH value and hydrolyzed nitrogen secure the product's preservation stability. Keywords: starter cultures, residual nitrite. Keywords: meat products, starter culture.
СРАВНИТЕЛЬНАЯ ХАРАКТЕРИСТИКА ФИЗИКО-ХИМИЧЕСКИХ СВОЙСТВ СЫРОВЯЛЕНЫХ КОЛБАС С ЗАКВАСКОЙ Градинарска Д.Н. (Республика Болгария)
Градинарска Диляна Николаева - кандидат технических наук, главный ассистент, кафедра технологии мяса и рыбы, технологический факультет, Университет пищевых технологий, г. Пловдив, Республика Болгария
Аннотация: основная задача специалистов пищевой индустрии сегодня заключается в обеспечении общественного здравоохранения путем обеспечения потребления целебных пищевых продуктов с высокой степенью безопасности и высокой пищевой ценностью. Информированные потребители предпочитают свежие мясные продукты. Сыровяленые колбасы попадают в эту категорию, потому что они хорошо сохранились, для более длительных периодов времени, а также за их специфический аромат. Цель этой работы заключается в том, чтобы определить изменения в содержание нитрита - нитрит важен для красноватого цвета в мясе, а также для антибактериальной защиты с помощью закваски отдельных микроорганизмов. Он, вместе с другими компонентами как влажность, pH и гидролизованный азот обеспечивает сохранение стабильности продукта. Ключевые слова: мясные продукты, стартовые культуры.
Introduction
In the meat industry, especially in food processing which undergoes a fermentation stage (salami, raw-dry sausages), the use of selected cultures of microorganisms has become a necessity for controlling this particular stage of fermentation [1, 3, 4]. The various microorganisms used in the biotechnology of fermented meat products have a well-defined role to play during the different stages of the technological process, thus contributing to the finite product's specificity [11, 12, 13, 16]. Depending on the main action undertaken, starter cultures can be categorized as follows: acidic cultures, cultures that lead to the formation of color and flavor, cultures for surface covering, cultures for bio-protection [6, 7, 9]. For the present study we used cultures from the first two categories: acidic cultures made up of lactobacilli and pediococci, the Lactobacillus, Pediococcus types. The present study's aim was to determine the nitrite's content variation- nitrite is imperative
for the reddish colour in meat and also for antimicrobial protection by using starter cultures of selected microorganisms, which, together with other components such as humidity, pH value and hydrolyzed nitrogen secure the product's preservation stability.
Experimental
In order to make the determinations we produced bulks (2-3 kg/bulk) of raw-dried Strandzhansko djado, the composition's fermentation being made by means of three starter culture types, which are displayed in Table 1.
Table 1. The starter culture types
Bulk Name of culture Microorganisms/Culture Use for 100g/kg
SD1 Baktoferment 61 S.carnosus 50
SD2 Rowu Ferm S.carnosus L.plantarum 60
SD3 Biobak Sal Plus L.plantarum P.acidilactici 50
The starter cultures available on the market at the moment assure the addition of some quality-adequate microorganisms and in sufficient quantity in order to develop the wanted fermentation. During the fermentation process a drop of the pH value occurs as a result of sugar conversion into lactic acid. Thus a gradual degradation of the pathogenic flora and unwanted microorganisms takes place. The acid medium also contributes to the nitrite's rapid reduction, which is initially added for the stability of the finite product's red color.
The sausage formulations were made from basic components and adequate ingredients for 100 kg composition, displayed in Table 2. The diagram of technological processing of Strandzhansko djado shows the following stages: cooling, leaving in the drying, airing, drying and ripening.
Table 2. The raw-dried sausage formulations' components (Strandzhansko djado)
Component/ Quantity, kg
ingredient SD1 SD2 SD3 Witness
Pork- Quality I: 70 70 70 70
Partially fatty pork 30 30 30 30
Salt 3.000 3.000 3.000 3.000
Nitrite 0.015 0.015 0.015 0.015
Savory 0.400 0.400 0.400 0.400
Red pepper 1.000 1.000 1.000 1.000
Chilli 0.150 0.150 0.150 0.150
Sugar 0.200 0.200 0.200 0.200
Starter culture + + + -
The chemical analyses we made were: Humidity: using the drying closet until reaching a constant mass (according to AOAC) carried out the determination of humidity Residual nitrites: the sodium nitrite was directly determined by the extracted samples in a warm environment and deproteinised by means of the Griess method (according to AOAC) [2]. Hydrolytic nitrogen: the ammonium was determined by means of distilling and being kept in acid (according to AOAC) [2]. The pH level: the pH value was determined by using the electrometric method (according to AOAC) [2].
Results and Discussions
The Humidity's Evolution: Samples with no further lactic bacteria addition were called 'witness samples'. The starter cultures used consisted of strains of Lactobacillus plantarum, Pediococcus acidilactici and Staphylococcus carnosus. The analyses data report a continuous drop in water activity, the diminution humidity speed being more intense at the beginning of the ripening-drying stage for samples with starter culture addition as opposed to samples with no starter culture
addition and a slower final phase (fig. 1). The main components' concentration for raw sausages (proteins, lipids,salt) and humidity loss occurred at the same time. By reporting them to 100 g dry substance these chemical components remain unchanged throughout the whole production cycle. The water elimination process evolved differently depending on the starter culture type used [10].
0 1 3 5 13 30
The production cycle, d
Fig. 1. The humidity's evolution in raw-dried sausages with starter cultures addition
pH Evolution: During the raw sausage processing the conversion of glucid (added and preexistent in meat) into lactic acid occurred. Lactic bacteria from the meat's natural microflora grouped or starter cultures influenced the glucids' fermentation in sausage components. The accumulation of lactic acid led to a pH value reduction, a more obvious drop was noticed during the first five days of processing, being followed by a final stage of drying-ripening that wasdifferentiated by the samples' nature [9]. The starter cultures accelerated the formation of lactic acid and led to a more drastic drop in the pH value (fig. 2).
0 1 3 5 13 30
The production cycle, d
Fig. 2. The pH evolution in raw- dried sausages with starter cultures addition
The Residual Nitrite's Evolution: The nitrites are used for raw product components (salami and sausages) to prevent the side effects. The nitrites are used in the meat product compositions for the stimulation of their pink-reddish colour effect in doses from 3 to 50 mg NO2 / kg [5]; for the typical aroma in doses from 20 to 40 mg NO2 / kg [15]; for the inhibiting of the fat oxidation and for the controlling of the altering microorganisms'development (Pseudomonas and Enterobacter) and
pathogenic bacteria (Staphylococcus aureus, Listeria monocytogenes,Clostridium Botulinum, Salmonella) in doses from 80 to 150 mg NO2/ kg [17]. The nitrites prevent the spore germination of Clostridium Botulinum and inhibits the production of deadly botulinic toxin in doses from 10 to 160 mg NO2 / kg. Our results demand a continuous degradation of the residual nitrites throughout the whole production process, more intensively in bulks made with the starter cultures. The drastic disappearance of the nitrite from the system during the first days of production coincides with the formation of nitrozopigments by conversing meat pigments. Through their development and metabolism the lactic bacteria synthesized the lactic acid which favoured the conversion of the nitrite into NO, a very reactive chemical form. The residual nitrite levels from finite products (after 30 days of ripening for sausages) were all reduced, being under the level of 1.0 mg/100g [8, 14]. These reduced residual nitrite levels associated with reduced values of water activity have secured the microbian and oxydative stability for the analysed products.
Fig. 3. The evolution of the residual nitrite for Strandzhansko djado with starter cultures addition
The Dynamycs of Protheolitical Processes: The microflora's protheolitical activity was evaluated by the determination of theammonium evolution throughout the whole period of processing. The data referring to the ammonium accumulation are displayed in fig. 4. As can be seen from the graph the ammonium had a slight growth influenced by the nature of starter culture used. The ammonium accumulations during the first process phases correlate with high degree of water, a reduced amount of salt, with a high glucid amount and a higher pH value, factors that determine the multiplying of the microflora. These microorganisms secrete enzymes involved in the hydrolising of protein in decarbolization and desamination of aminoacids. According to Sanz (1998) microbial proteases play an important part in the oligopeptide hydrolization. By using the Staphylococcus carnosus starter culture the ammonium accumulation and also the possibility of forming the biogenic amines like histamine in raw-dry products are drasticly reduced.
Fig. 4. The Ammonium accumulation in raw-dried Strandzhansko djado with starter cultures addition
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The water activity evolution: In order to determine the raw-dry sausage quality and stability we calculated the values of water activity. The water activity is of paramount importance for the raw-dried meat products' quality and stability. It is a way of measuring the water's influence on the microbial and biochemical processes, which occur in a product. The values of water activity in stage of the processing for all the experimental bulks made with / without the starter cultures are presented in fig. 5.
Fig. 5. The water activity evolution during ripening in raw-dry sausages
Conclusions
The final values of the water activity were under 0.9 for each sausage sample with starter culture addition, values at which it the production of the botulinum toxin is not possible by Clostridium botulinum. All the experimental bulks of raw sausages had very low residual nitrite levels, stimulated by addition of lactic bacteria starter culture, which favored the pH value reduction of sausage compositions under 5 and the nitrite's conversion into nitrogen oxide. The lactic acid gives the product its typical taste, contributing to the growth in texture firmness and also to the inhibiting of negative stafilococi and Escherichia coli bacteria development. Pediococcus acidilactici, Lactobacillus plantarum and Staphylococcus carnosus contributed to the reduction of the ammonium accumulation in the finite analysed products, a process possible by inhibiting the development of the altering bacteria.
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