Rheological, textural and microstructural features of probiotic whey cheeses

Whey cheeses have been manufactured with probiotic bacteria e viz. Bifidobacterium animalis Bo and Lactobacillus casei LAFTIrL26, from combinations of bovine whey and milk, following protein denaturation at 90 ºC; they were subsequently inoculated (at 10%) with those strains, and homogenized afterwards; additives such as salt and sugar were then incorporated; and the resulting solid matrices were stored at 7º C for up to 21 d. Oscillatory measurements and instrumental texture profile analyses were performed, and sensory analyses were carried out by a trained panel. Microstructural features were in addition ascertained by scanning electron microscopy. L. casei exhibited a higher acidifying activity than B. animalis, which produced distinct textures; higher firmness and viscoelasticity were indeed found in matrices inoculated with the former. Incorporation of sugar and L. casei favoured consumer acceptability, relative to plain matrices. Microstructural differences were detected between matrices at different times of storage and formulated with distinct additives.info:eu-repo/semantics/acceptedVersionhttps://creativecommons.org/licenses/by-nc-nd/4.0

Antioxidant activity of sugar molasses, including protective effect against DNA oxidative damage

Extracts were obtained from molasses, a byproduct of the sugar industry, via a number of chromatographic steps. Their antioxidant capacity was studied, including the inhibitory effect upon DNA oxidative damage;the phenolic compound profile there of was ascertained as well. Two extracts exhibited significant antioxidant features, expressed by their capacity to decolorize ABTS radical cation and to scavenge hydroxyl free radicals (via deoxyribose assay). Those 2 extracts also brought about protection against induced DNA oxidative damage (via decreasing DNA scission, as assessed by electrophoresis).The phenolic compounds syringic acid,p-hydroxybenzoic acid, vanillic acid, p-hydroxybenzaldehyde, and ferulic acid were positively identified and quantified

Effect of particle size upon the extent of extraction of antioxidant power from the plants Agrimonia eupatoria, Salvia sp. and Satureja montana

The dependence of the extent of aqueous extraction of antioxidant compounds on particle size and contact time was studied for three important medicinal plants, that are commonly used in infusions: agrimony, sage and savoury. The effect of extraction time was dependent on the plant considered; however, ca. 5 min can be taken as the minimum period required to assure an acceptable degree of extraction of those compounds. As expected, a smaller particle size led to a higher extraction extents; a typical value of 0.2 mmis accordingly recommended. Chlorogenic acid was the dominant phenolic compound extracted from agrimony, whereas caffeic acid dominated in the case of sage or savoury. A mathematical model based on Fick’s law was developed from first principles, and its two parameters were suitably fitted to the experimental data generated – in attempts to predict the evolution of antioxidant capacity extracted during contact time, for each plant and each particle size

Effect of the incorporation of salted additives on probiotic whey cheeses

The research effort described here has focused on incorporation of Lactobacillus casei, in whey protein matrices, in the presence of selected salty additives. Those matrices were produced via thermal processing of a combination of either ovine or bovine whey (or a mixture thereof) with ovine milk, and were inoculated (at 10%) with L. casei strain LAFTI®L26; salt, salt and herbs, or salt and xanthan were further added to such matrices, which were then homogenized and stored at 7 °C for up to 21 d. In general, viable cell numbers maintained or even increased throughout the storage period, irrespective of the type of salty additive considered. Partial depletion of lactose was detected, and concomitant production of lactic acid throughout the 21 d-period of storage; lower lactic acid concentrations were found in matrices containing salty additives. In matrices with xanthan (SX), the probiotic strain exhibited the lowest metabolic activity. Matrices SX were less soft and firmer than the others, by the end of storage, and were similar to matrices with herbs (SH). The incorporation of salty additives affected bacterial metabolism, in terms of glycolysis and proteolysis, which in turn had a significant impact on the development of textural propertiesinfo:eu-repo/semantics/acceptedVersio

Flow analysis method for hydroxyproline determination to assess collagen content in fish skin

Collagen is a protein with several applications, with weak antigenicity, low toxicity, and high nutritional value. Usually, it is extracted from bovine skin, but a project was designed proposing an alternative to extract collagen from fish skin. This alternative was tested by assessing the collagen content in fish skin based on the determination of hydroxyproline (HYP), one of the most abundant amino acid present in collagen (Sotelo et al., 2016). Therefore, the determination of HYP requires the hydrolysis of the fish skin, to break collagen in its amino acids, and the HYP value quantified relates to the collagen content. This was previously assessed to be 38 μg of HYP per mg of pure collagen. In this context, the aim of the described work was to develop an automatic method based on flow injection analysis approach to determine HYP. The determination was based on the redox reaction with permanganate (Farokhi et al., 2002) and the consequent decrease of colour intensity registered. The best conditions for the determination were studied, namely, reagent concentration, sample volume, flow rate and reaction time. The developed method enables the determination of the HYP in a faster, simpler and accurate way, with less toxic solutions.info:eu-repo/semantics/publishedVersio

Collagen determination in fish skin: development of a flow analysis system for quantification of hydroxyproline

Collagen is a protein with various applications, namely in the food area. It has valuable properties, since it is a polymer with weak antigenicity, low toxicity, and high nutritional value, among other features [1]. Its extraction from mammalian sources, i.e., bovines, is decreasing due to health and environmental problems and, therefore, fish have become a good alternative for collagen resources [2].One way to quantify the collagen present in fish skin, in order to obtain high-value fractions, is the determination of hydroxyproline (HYP), an amino acid highly present in collagen [1]. The determination of HYP from fish skin requires the hydrolysis of a skin section, to break collagen in its amino acids and the HYP value quantified is compared to the amount present in pure collagen, studied previously (38 μg of HYP per mg of pure collagen). The quantification of HYP is based on its oxidation combined with the reaction with DAB (dimethylaminobenzaldehyde) that forms a chromophore-coloured product. The HYP can then be correlated with the spectrophotometric measurement of this coloured product. A batchwise approach was performed to study the best reaction conditions, namely different reagents, heating times and proportions.The main goal of this work is to develop an automated flow injection analysis (FIA) method, to miniaturize the determination of HYP. Several operation parameters like flow rates, number of channels, tube diameters and lengths of reactors will be studied to optimize the developed FIA method.info:eu-repo/semantics/publishedVersio

Impact of LAB from Serpa PDO cheese in cheese models: towards the development of an autochthonous starter culture

Serpa is a protected designation of origin (PDO) cheese produced with raw ewes’ milk and coagulated with Cynara cardunculus. Legislation does not allow for milk pasteurization and starter culture inoculation. Although natural Serpa’s rich microbiota allows for the development of a unique organoleptic profile, it also suggests high heterogeneity. This raises issues in the final sensory and safety properties, leading to several losses in the sector. A possible solution to overcoming these issues is the development of an autochthonous starter culture. In the present work, some Serpa cheese Lactic acid bacteria (LAB)-isolated microorganisms, previously selected based on their safety, technological and protective performance, were tested in laboratory-scale cheeses. Their acidification, proteolysis (protein and peptide profile, nitrogen fractions, free amino acids (FAA)), and volatiles generation (volatile fatty acids (VFA) and esters) potential was investigated. Significant differences were found in all parameters analyzed, showing a considerable strain effect. Successive statistical analyses were performed to compare cheese models and Serpa PDO cheese. The strains L. plantarum PL1 and PL2 and the PL1 and L. paracasei PC mix were selected as the most promising, resulting in a closer lipolytic and proteolytic profile of Serpa PDO cheese. In future work, these inocula will be produced at a pilot scale and tested at the cheese level to validate their application.info:eu-repo/semantics/publishedVersio