Immunofluorescence detection of milk protein in meat products

Nowadays there are various vegetable protein additives intended for the manufacture of meat products in the food industry. These ingredients include both, plant-origin as well as animal-origin proteins. The most common vegetable additives include various types of flour, starch, fiber and plant protein. Among animal proteins, the most commonly used are plasma, collagen or milk protein. Milk protein is added to meat products due to its functional properties, such as emulsifying fats, improving the holding capacity of meat, improving juiciness, gel-forming capacity and affecting the taste of the product. Usage of these proteins, however, is currently limited by the effective legislation, not only in order to prevent consumer deception, but also because of their potential impact on consumers' health of. Thus, this issue has received considerable attention not only in the Czech Republic, but also globally. The main risk is the impossibility of selecting a suitable foodstuff for individuals with potential allergic reactions. The only option for allergic consumers to protect themselves is to strictly exclude the given allergen from their diet. Although the number of studies dealing with the reduction or loss of allergenicity is increasing, yet these practices are not common. Most of the population suffering from food allergies is thus still dependent on strict exclusion of foodstuffs causing adverse allergic reactions from their diet. Detection of allergens in foodstuffs is unfortunately quite difficult due to the fact that they occur in trace amounts and are often masked by different parts of the foodstuff. This research dealt with the detection of milk protein in meat products purchased in the market network of the Czech Republic, whereas declaration given by the manufacturer on the packaging for the small meat products purchased from the market was used to verify the detection of milk protein by the immunofluorescence method. 20 products were examined, these were selected with regard to the presence of milk protein that was declared by the manufacturer on the packaging. Method validation was performed by comparing the positive results from the investigated method with information on the packaging of the meat product. Milk protein was detected in 84.62 per cent of samples where the manufacturer declared the presence of milk or cheese on the package and additionally in 85.71 per cent of samples where the manufacturer declared the presence of milk protein. The results show that the immunofluorescence method is suitable for the detection of milk protein in meat products

Detection of native starches in meat products using histochemical Lugol Calleja method

Starch has been still used in food industry today as one of the main additives in foodstuffs. The reason for the use of starches in foodstuffs is their ability to bind water and to contribute to the coherent structure of the final product. However, the presence of starch in some foodstuffs is limited by legislation. These are especially meat products where legislation prohibits using starches. This study deals with determination of native starches using histochemical Lugol Calleja staining in meat products. The targeted structures of this successive staining are starches and collagen ligaments. Other structures can also be detected, based on the knowledge of their morphology. Within the scope of this study, the possibility of histochemical proof on the basis of reaction between Lugol's iodine solution and starch amylose was demonstrated. From the samples analyzed, the following criteria for the method were determined: Repeatability and repeatability of intralaboratory results was 100%, selectivity was determined to be 1.03, specificity of the method was determined to be 0.9, limit of detection was established to be 100% for 0.001 g.kg-1 of the addition, and 87.7% for the concentration of 0.0001 g.kg-1 of the starch addition. Based on the results it is obvious that the method is suitable for determination of native starches in meat products, and, in combination with staining of other foodstuffs ingredients, it gives a complex view of the composition and structure of the meat product

Possibilities of microscopic detection of isolated porcine proteins in model meat products

In recent years, various protein additives intended for manufacture of meat products have increasing importance in the food industry. These ingredients include both, plant-origin as well as animal-origin proteins. Among animal proteins, blood plasma, milk protein or collagen are used most commonly. Collagen is obtained from pork, beef, and poultry or fish skin. Collagen does not contain all the essential amino acids, thus it is not a full protein in terms of essential amino acids supply for one's organism. However, it is rather rich in amino acids of glycine, hydroxyproline and proline which are almost absent in other proteins and their synthesis is very energy intensive. Collagen, which is added to the soft and small meat products in the form of isolated porcine protein, significantly affects the organoleptic properties of these products. This work focused on detection of isolated porcine protein in model meat products where detection of isolated porcine protein was verified by histological staining and light microscopy. Seven model meat products from poultry meat and 7 model meat products from beef and pork in the ratio of 1:1, which contained 2.5% concentration of various commercially produced isolated porcine proteins, were examined. These model meat products were histologically processed by means of cryosections and stained with hematoxylin-eosin staining, toluidine blue staining and Calleja. For the validation phase, Calleja was utilized. To determine the sensitivity and specificity, five model meat products containing the addition of isolated porcine protein and five model meat products free of it were used. The sensitivity was determined for isolated porcine protein at 1.00 and specificity was determined at 1.00. The detection limit of the method was at the level of 0.001% addition. Repeatability of the method was carried out using products with addition as well as without addition of isolated porcine protein and detection was repeated 10 times. Repeatability in both, positive and negative samples, for isolated porcine protein was determined at 100%. The results show that the histological processing of cryosections stained using Calleja is suitable for detecting isolated porcine protein in meat products

Evaluation of fat grains in gothaj sausage using image analysis

Fat is an irreplacable ingredient in the production of sausages and it determines the appearance of the resulting cut to a significant extent. When shopping, consumers choose a traditional product mostly according to its appearance, based onwhat they are used to. Chemical analysis is capable to determine the total fat content in the product, but it cannot accurately describe the shape and size of fat grains which the consumer observes when looking at the product. The size of fat grains considered acceptable by consumers can be determined using sensory analysis or image analysis. In recent years, image analysis has become widely used when examining meat and meat products. Compared to the human eye, image analysis using a computer system is highly effective, since a correctly adjusted computer program is able to evaluate results with lower error rate. The most commonly monitored parameter in meat products is the aforementioned fat. The fat is located in the cut surface of the product in the form of dispersed particles which can be fairly reliably identified based on color differences in the individual parts of the product matrix. The size of the fat grains depends on the input raw material used as well as on the production technology. The present article describes the application of image analysis when evaluating fat grains in the appearance of cut of the Gothaj sausage whose sensory requirements are set by Czech legislation, namely by Decree No. 326/2001 Coll., as amended. The paper evaluates the size of fat mosaic grains in Gothaj sausages from different manufacturers. Fat grains were divided into ten size classes according to various size limits; specifically, 0.25, 0.5, 0.75, 1.0, 1.5, 2.0, 2.5, 5.0, 8.0 and over 8 mm. The upper limit of up to 8 mm in diameter was chosen based on the limit for the size of individual fat grains set by the legislation. This upper limit was not exceeded by any of the products. On the other side the mosaic had the hightest representation of 0.25 mm fat grains

Rheological and fermentation properties of doughs and quality of breads from colored wheat varieties

The objective of this study was to examine the rheological and fermentation behavior of doughs prepared from five different colored wheat varieties (black AF Zora, yellow KM 111-18, purple AF Jumiko, blue AF Oxana and red Vanessa - chosen as a standard), which contain polyphenolics in the outer layers of grains. Three wholemeal flour fractions (fine, semi-coarse and coarse) were used for each variety. The flour fractions differed in the particle size of the bran, the ash content and thus the phenolic compound content. The baking trials, texture and sensory analyses of breads were performed, to assess their overall acceptability.The coarser granulation of flour fractions, average hardness (8.587>77%), cohesiveness (78>75>70%) and resilience (35>32>27%) decreased. Moreover, the increase in off-flavors was detected with higher bran content. Regarding the flour granulation, the fine fraction seemed to be the most suitable due to its high gas-retention capacity. The best products in terms of both dough and bread quality reached blue AF Oxana and yellow KM 111-18.Utilization of colored wheat in bakery industry may present a good strategy of providing value-added products to the consumers.IGA/FT/2022/008, QK1910343; Ministerstvo ZemědělstvíInternal Grant Agency of Tomas Bata University in Zlin [IGA/FT/2022/008, QK1910343]; Ministry of Agriculture of the Czech Republi

Physico-Chemical and Melissopalynological Characterization of Czech Honey

Geographical and botanical origin of honeys can be characterized on the basis of physico-chemical composition, sensory properties and on the basis of melissopalynological analysis. No comprehensive description of the characteristics of Czech honey has been published so far. This study provides insights that are important for correct classification. The study analysed 317 samples of authentic honey from randomly selected localities. Due to the diversity of the landscape, the typical honey of the region is blend honey with a predominance of blossom honey. According to the pollen profile and electric conductivity, the honeys were sorted into the following: Brassica honey (BH), Floral honey (FH), Fruit tree honey (PH), Honeydew (HD), Lime tree honey (LH), Robinia pseudoacacia honey (RH), and Trifolium honey (TH). Physico-chemical properties, including higher carbohydrates, were determined for the honeys and their pollen profiles were examined. The physico-chemical properties and pollen profile are partially in compliance with the description of European monofloral honeys, except for RH and TH. Although they had the highest proportion of acacia pollen, amounting to >10% of all the Czech honeys, these RH honeys differ from the European standard, so they cannot be considered acacia honey. Further, PH honeys and FH polyfloral honeys were described. Most honeys contained a significant proportion of rapeseed pollen, which is one of the common agricultural crops grown in the Czech Republic. All the analysed honeys met the parameters defined by the legislation. Due to direct on-site sampling, honeys were characterized by a low 5-(hydroxymethyl)furfural (HMF) content (3.0 mg/kg) and high diastase activity (24.4 DN). Honeydew honeys had the highest proportion of higher carbohydrates, primarily of Melezitose (4.8 g/100 g) and Trehalose (1.3 g/100 g). The presence of higher carbohydrates was also confirmed in LH for Maltose (4.6 g/100 g) and Turanose (2.4 g/100 g)

Evaluation of the viscoelastic properties of pork liver pâté during sterilisation observed in situ

The first aim of the study was to observe in situ changes in the viscoelastic properties of pork liver pâté during an increase in temperature (the target temperature of 122 °C), holding it (10 min), and the subsequent cooling thereof using a dynamic oscillatory rheometry equipped with a pressure cell. At the same time, the samples were treated according to the same sterilisation mode in an autoclave. The second objective was to characterise the physical, chemical and microscopic properties of the sterilised pork liver pâté samples after 7 days of storage at 5 °C. A sharp decrease in the values of the storage (G'; Pa) and loss (G''; Pa) moduli up to ≈58 °C was followed by a stagnation of these parameters up to ≈70 °C and a further increase in G' and G'' up to ≈85 °C. After cooling the sterilised samples, the G' and G'' values were significantly higher than those of the original untreated sample. Knowledge about the course of the viscoelastic moduli development during sterilisation and subsequent cooling and the quality characteristics of final food products is crucial for the control of these processes during manufacturing and for information important for pipeline transport. In the future, selected hydrocolloids could be evaluated as possible substances for confirmation of their effect on the viscoelastic properties during sterilisation.Army of the Czech Republic; Ministerstvo Obrany České Republiky, MOČRMinistry of Defence of the Czech Republi

Detection of Carrageenan in Meat Products Using Lectin Histochemistry

Carrageenan is a polysaccharide that is widely used in the food industry. Due to its water holding capacity, there is a higher risk of adulteration for economic reasons related to it. A verifiable method for detecting carrageenan is still missing in the food inspection sector. The detection of carrageenan in meat products is not well described. Our study describes lectin histochemistry as a novel approach for carrageenan detection. Within this study, the detection of carrageenan in meat products by lectin histochemistry is validated. Lectins of Arachis hypogaea (PNA) and Bandeiraea simlicifolia (BSA), specific for galactose units of carrageenan, were used. The samples included model meat products (ground chicken-meat products) and meat products from retail markets (chicken and pork hams, sausages, salami, and dried sausages). The limit of determination (LoD) of this method was set at 0.01 g kg−1. The method sensitivity for lectin PNA reached 1, and, for lectin BSA, it reached 0.96. Method specificity for lectin PNA was 1, and, for lectin BSA, it was 1.33. Cross-reactivity with other hydrocolloids tested was not confirmed. The results confirm that lectin histochemistry is suitable for detecting carrageenan in meat products

Detection of Carrageenan in Cheese Using Lectin Histochemistry

Carrageenan is a substance widely used as an additive in the food industry. Among other things, it is often added to processed cheese, where it has a positive effect on texture. Processing of such cheese involves grinding, melting and emulsifying the cheese. There is currently no official method by which carrageenan can be detected in foodstuffs, but there are several studies describing its negative health impact on consumers. Lectin histochemistry is a method that is used mainly in medical fields, but it has great potential to be used in food analysis as well. It has been demonstrated that lectin histochemistry can be used to detect carrageenan in processed cheese by Human Inspection and Computer-Assisted Analysis (CIE L*a*b*). The limit of detection (LoD) was established at 100 mg kg−1 for Human Inspection and 43.64 for CIE L*a*b*. The CIE L*a*b* results indicate that Computer-Assisted Analysis may be an appropriate alternative to Human Inspection. The most suitable parameter for Computer-Assisted Analysis was the b* parameter in the CIE L*a*b* color space