Comparison of Synergistic Effect of Nisin and Monolaurin on the Inactivation of Three Heat Resistant Spores Studied by Design of Experiments in Milk

Spore forming bacteria are special problems for the dairy industry. Heat treatments are insufficient to kill the spores. This is a continuously increasing problem for the industry, but we should be able to control it. In this context, we investigated the combined effect of nisin, monolaurin, and pH values on three heat resistant spores in UHT milk and distilled water and to select an optimal combination for the maximum spore inactivation. The inhibitory effect of nisin (between 50 and 200 IU/ml), monolaurin (ranging from 150 to 300 µg/ml), and pH (between 5 and 8) was investigated using a central composite plan. Results were analyzed using the response surface methodology (RSM). The obtained data showed that the inactivation of Bacillus spores by the combined effect of nisin-monolaurin varies with spore species, acidity, and nature of the medium in which the bacterial spores are suspended. In fact, Terribacillus aidingensis spores were more resistant, to this treatment, than Paenibacillus sp. and Bacillus sporothermodurans ones. The optimum process parameters for a maximum reduction of bacterial spores (∼3log) were obtained at a concentration of nisin >150 IU/ml and of monolaurin >200 µg/ml. The current study highlighted the presence of a synergistic effect between nisin and monolaurin against heat bacterial spores. So, such treatment could be applied by the dairy industry to decontaminate UHT milk and other dairy products from bacterial spores.

THE EFFECT OF WILD HONEY (Apis dorsata Fabr.) CONCENTRATIONS ON PH AND ORGANOLEPTIC VALUES OF ULTRA HIGH TEMPERATURE (UHT) MILK

The research aims to observe the effect of addition wild honey (Apis dorsata Fabr.) on pH and organoleptic values of ultra high temperature milk (UHT). The research was done using an experimental method using a non-factorial completely randomized design with five levels using SPSS 16. Different concentrations of wild honey (A1= control; A2= 5%; A3= 10%; A4= 15% and A5=20%) were used. The data was statistically analyzed using analysis of variance (ANOVA) with 5% significance level and further processed with Duncan's Multiple Range Test (DMRT). Organoleptic tests for colour, taste and overall preference were also done using qualitative tests (scores). The value of pH gave a significant value (P<0,01) between treatment. The higher the use of wild honey concentration, the lower the pH value produced. The higher the concentration of wild honey, the higher the organoleptic value. The best treatment in terms of colour, taste, and level of preference was observed in the sample with the 20% honey concentration, each of which resulted in an average score of 4.

Pengaruh Penggunaan Cairan (Susu UHT, Santan Segar, dan Santan Instan) pada Pembuatan Macaroni Schotel Terhadap Daya Terima Konsumen

ABSTRACT The objective of this study was to determine and analyze the effect of the usage of liquid (UHT milk, fresh coconut milk, and instant coconut milk) on Macaroni Schotel on consumer acceptance based on aspects of color, taste, aroma, and texture. This research was conducted at the Pastry and Bakery Laboratory of Food & Nutrition Program, State University of Jakarta. When the study began in October 2019 until March 2020. The method used was an experimental method. The sample in this study was a Macaroni Schotel with the usage of 400ml liquid (UHT milk, fresh coconut milk, and instant coconut milk) tested on 30 untrained panelists who assessed all aspects. Based on the results of hypothesis analysis using the Friedman test on aspects of color, taste, and texture showed the effect of the usage of liquid (UHT milk, fresh coconut milk, and instant coconut milk) to the making of Macaroni Schotel does not have a signficant effect on consumer’s acceptance so the formula for using the coconut milk must be tested again to gain better results.

Lactose quantification in UHT milk by high-performance liquid chromatography and cryoscopy (freezing point depression)

Due to the large number of people with lactose maldigestion, the dairy industries have increased production and diversity of low lactose and lactose-free foods. Consequently, the need to control the lactose hydrolysis process has also risen. This study aimed to correlate freezing point depression (cryoscopy) and lactose concentration, quantified by high-performance liquid chromatography (HPLC), in UHT milk. To accomplish this, UHT milk samples were subjected to seven lactose hydrolysis treatments, using lactase enzyme, resulting in different lactose concentrations. All samples were subjected to HPLC analysis and freezing point measurement, using a cryoscope. The results were plotted on a graph and a linear regression was performed. There was a strong correlation between lactose concentration and freezing point (R = 0,9973) and the coefficient of determination (R2) was 0,9946, which means that 99,46% of the variability of the response data is explained by the linear regression model. Therefore, the results point to the feasibility of estimating the lactose concentration in milk during the hydrolysis process for the production of low lactose milk, by cryoscopy, a quick analysis, with lower cost compared to HPLC and that is already among the analyses commonly performed in dairy industries.

Influence of Ultra-Heat Treatment on Properties of Milk Proteins

Milk can be considered one of the primary sources of nutrients for the mammalian neonate. Therefore, milk and milk-based products, such as infant formula, whey protein isolate, different varieties of cheese, and others are prepared to meet the nutritional requirements of the consumer. Due to its significant nutritional components and perishable nature, a variety of pathogenic microorganisms can grow and multiply quickly in milk. Therefore, various heat treatments can be employed for the improvement of the shelf life of milk. In comparison to pasteurized milk, due to excessive and severe heating, UHT milk has a more cooked flavor. During storage, changes in the physicochemical properties of milk can lead to off-flavors, undesirable browning, separation of fat, sediment formation, or gelation during the subsequent storage. Several important factors such as processing parameters, time-temperature abuse (storage condition), and packaging type also influence the quality characteristics and consumer acceptance of the milk; however, the influence of heat treatments on milk protein is inconstant. The major protein modifications that occur during UHT treatment are denaturation and aggregation of the protein, and chemical modifications of its amino acids. These UHT-induced protein alterations can change digestibility and the overall biological influence of the intake of these proteins. Therefore, this review is focused on the influence of UHT on the physicochemical and structural attributes of milk proteins during storage. There are many indications of milk proteins present in the UHT milk, and milk products are altered during processing and storage.

Towards discrimination of mammary pathogenic Escherichia coli (MPEC) in cattle based on possession of different iron acquisition systems

Most efforts to elucidate virulence mechanisms of mammary pathogenic Escherichia coli (MPEC), causative agent of bovine clinical mastitis, have been failed but some recent studies introduced iron acquisition systems as major role players in pathogenicity. Here, we investigated the different iron uptake systems genotypes and assessed how they relate to virulence potential of MPEC. In total, 217 E. coli isolates (MPEC= 157, fecal isolates= 60) were screened for the presence of nine genes related to iron acquisition (iroN, iutA, fecA, fyuA, sitA, irp2, iucD, chuA and tonB) and phylogenetic groups were also determined. Next, bacterial growth potential and survival in raw and UHT milk which are representative for crucial steps in mastitis development were evaluated. In addition, the mineral consumption of E. coli cultured in milk were measured. The results showed that MPEC strains considerably tend to possess fecA (93%, p= 0.000) and belong to phylogenetic group A (42%, p= 0.042). The fecA+ strains from both mastitis and fecal E. coli had a significant (p= 0.000) growth potential in raw and UHT milk. Interestingly, for the first time, it was shown that fecA+ isolates consumed less amounts of iron and other metal ions. Overall, it seems that the uptake systems related to fecA contributes to overcoming harsh conditions of milk and genetic lineages could also affect pathogenicity of MPEC. These findings could lead us to define MPEC with more clarity based on genotypes or growth potential in milk and possibly promote novel solutions to control mastitis more effectively in future.ImportanceMastitis is one of the most costly concerns in bovine medicine and the main cause of antibiotic use in dairy herds’ worldwide. As a rule of thumb, it was believed that extraintestinal pathogenic E. coli expands iron acquisition virulence arsenal to enhance pathogenic potential in the environments of the host outside the intestines. The present study indicated that the long believed idea of possession of diverse mineral acquisition systems and siderophores in all ExPEC groups could be a fairy tale. Along with recent studies, the present research showed that the fec operon could be the minimal necessary factor to overcome the harsh conditions of milk with limiting mineral concentrations. Obviously, the fecA+ isolates were fast-growing and consumed less amounts of minerals. It seems that the fec locus and its related metabolic pathways could be the potential targets for diagnostic, preventive, and therapeutic purposes.

Avaliação da rotulagem de leites UHT comercializados no Vale do Taquari-RS

Resumo A legislação brasileira estipula que os rótulos de alimentos devem conter informações obrigatórias e essenciais para os consumidores conhecerem a procedência e a composição do produto em questão. Nesse sentido, os órgãos de fiscalização estabeleceram normas e leis específicas sobre as informações que devem estar presentes nos rótulos das embalagens para padronizá-los e garantir que os mesmos não causem engano, dúvidas ou danos ao consumidor. O objetivo deste trabalho foi verificar a rotulagem de embalagens de leite UHT segundo as normas vigentes. Foram avaliados os rótulos das embalagens de nove marcas de leite integral e desnatado comercializados no Vale do Taquari (RS). Os resultados obtidos permitiram concluir que grande parte dos rótulos analisados apresentaram não conformidades com a legislação brasileira e, devido a isso, somente estariam aptos para comercialização mediante ajustes em relação à legislação vigente. Palavras-chave: Leite UHT; rotulagem; legislação; embalagem. Abstract Verification of labels of milk commercialized at grocery stores and supermarkets in Vale do Taquari - RS Brazilian law defines that food labels must contain mandatory and essential information to inform consumers the origin and the composition of the product in question. Therefore, regulating agencies have established rules and laws with the aim to standardize information on packaging labels, as well as ensure that they do not confuse, cause doubt or damage to the consumer. The aim of this study was to verify if the labeling of UHT milk follows current regulations. The packaging labels of nine brands of both whole and skim milk sold Vale do Taquari - RS were evaluated. Results of our analysis lead to the conclusion that most of the labels present noncompliance with current rules and legislation. Hence, they would only be suitable for commercialization after adjustments obeying Brazilian legislation. Keywords: UHT milk; labeling; legislation; package. Resumen Análisis del etiquetado de la leche UHT comercializados en el Valle del Taquari-RS La legislación brasileña estipula que las etiquetas de los alimentos deben contener informaciones obligatorias y esenciales para que los consumidores conozcan el origen y la composición del producto en cuestión. En ese sentido, las agencias de inspección han establecido reglas y leyes específicas acerca de las informaciones que deben estar presentes en las etiquetas de los empaques para que estén estandarizados, así como para asegurar que no engañen, siembren dudas o causen daño al consumidor. El objetivo de este trabajo fue verificar las etiquetas de los envases de leche UHT según las normativas vigentes. Fueron evaluadas las etiquetas de empaque de nueve marcas de leche integral y desnatada comercializados en el Valle del Taquari (Vale do Taquari - RS). Los resultados obtenidos permitieron concluir que gran parte de las etiquetas analizadas no presentaban inconformidades con la legislación brasileña y, por ello, solamente estarían aptas para la comercialización delante ajustes en conformidad con la legislación vigente. Palabras clave: Leche UHT; etiquetado; legislación; el empaquetado.