Dolors Parés

Heat-induced gelation of porcine blood plasma proteins as affected by pH.

Porcine plasma is a by-product of the meat industry that can be used as a food ingredient. It is a protein mixture, hence its composition can be modified to meet specific functionality requirements. In the present paper, the gelation properties of plasma and its two major fractions (serum and albumin) have been studied at pH 4.5, 6.0 and 7.5. Polyacrylamide gel electrophoresis (SDS-PAGE) revealed that albumin was the constituent that remained soluble to a larger extent during heat-treatments, and that acidic coagulation occurred at pH 4.5, making weak interactions the predominating ones between protein aggregates. Differential scanning calorimetry (DSC) and rheological tests showed that both the thermal stability and the gelation point of protein solutions were lower as pH decreased. The textural properties and water-holding capacities of plasma and albumin gels were more pH-dependent than serum. Albumin gels were the weakest and those of plasma at pH 7.5, the strongest. It has been determined that interactions between protein fractions play a key role in the gelling properties due to synergistic effects. This knowledge should be useful in the engineering of a plasma derivative product designed for specific food requirements, by reformulating its natural composition and enhanced by controlling pH.

Porcine plasma as polyphosphate and caseinate replacer in frankfurters

The aim was to replace polyphosphate and caseinate by porcine blood plasma as functional ingredients in frankfurters. Three trials, each consisting of one control, formulated with caseinate and tripolyphosphate, and one test, formulated with plasma, were carried out in a pilot plant. The frankfurters with plasma were compared to their respective controls by determining the composition, water holding capacity, cooking losses, internal colour, texture, microstructure, sensorial characteristics, and overall acceptance. No significant differences were found in proximate analysis, WHC, and cooking losses. Texture was not affected by the replacement, according to both sensorial and instrumental measurements. Nevertheless, the panellists detected the presence of animal taste and odour in plasma-containing sausages. Despite this, their overall acceptance was scored as 6.3 in a 10 maximum scale, so plasma could be considered as an interesting alternative to produce healthier and cheaper frankfurters.

Functional and quality characteristics of the red blood cell fraction from biopreserved porcine blood as influenced by high pressure processing.

The effects of high hydrostatic pressure (HHP) processing, at 400MPa for 15min at 20°C, on the microbiological and functional characteristics of the red blood cell (RBC) fraction obtained from porcine blood, previously preserved by means of lactic acid bacteria (LAB) was studied. Biopreservation was achieved by incubation of inulin-enriched blood inoculated with a LAB strain (Enterococcus raffinosus PS99) for 72h at 5°C. Results showed that incubation of blood with added E. raffinosus followed by HHP treatment reduced the levels of contaminant coliforms, proteolytic, hemolytic bacteria, and Pseudomonas spp. on RCB. Color parameters, protein solubility, foaming and emulsifying properties, as well as texture and water holding capacity of heat-induced gels from RBC were not seriously damaged by the combined treatments. This is a new approach to process and preserve animal blood fractions for the development of functional and/or nutritional food ingredients with added value.

Scale-up of the process to obtain functional ingredients based in plasma protein concentrates from porcine blood

The feasibility of a scaled-up process to obtain two protein concentrates from porcine blood plasma, i.e. serum and albumin, for use as functional food ingredients was assessed. The process consisted of fractionating plasma proteins by salting out, concentrating and purifying fractions by means of membrane technology, and subsequently dehydrating through spray-drying. The fractionation process allowed a good isolation of the desired proteins, which were then concentrated and desalted in a tangential flow filtration (TFF) process combining ultra and diafiltration. Purification, pre-concentration and dehydration were successfully achieved. The functional properties of dehydrated serum and albumin were determined. As compared to the same hemoderivatives obtained by a lab-scale production system, serum maintained the gelling properties; albumin exhibited similar foaming properties; and both serum and albumin concentrates showed slightly improved emulsifying properties.

Blood by-products as ingredients in processed meat

Abstract: Blood from slaughtered animals is a natural by-product of the meat industry that has the potential to generate a range of food ingredients, especially suitable for meat products. Well-defined nutritional and functional ingredients which have special uses, such as emulsifying and texturising agents, colourants and/or bioactive products, may be derived from neat blood. The challenge for the industry lies in the ability to make the necessary technical improvements to the bleeding/sticking stations in slaughterhouses and to the recovery of the blood itself, and its ability to reach the point that it can be exploited economically. The use of blood, as it is after collection or conveniently processed to produce intermediate food products, is discussed in this chapter.

Preservation of porcine blood quality by means of lactic acid bacteria

The capacity of 12 lactic acid bacteria (LAB) strains to preserve porcine blood during storage was evaluated. A general ability of LAB to prevent bloods hemolysis and to maintain the functional properties of plasma was observed. Two strains, PS99 (Enterococcus raffinosus) and TA43 (Lactobacillus reuteri), were selected for studies at 5°C according to their antibacterial activity in blood stored at 15°C. After 144h at 5°C, lower counts of coliforms, Pseudomonas spp., proteolytic and hemolytic bacteria were obtained in blood containing either PS99 or TA43 as compared to the non-inoculated blood. When inulin (2%) was added to blood, higher inhibition values were obtained and Enterococcus raffinosus (PS99) showed the best abilities for blood preservation. On the basis of these results it seems worthwhile to supplement blood with inulin and to inoculate it with an active LAB strain to avoid undesirable changes during chill storage, especially useful to prevent the effects of a cold-chain breakdown.

Color stabilization of porcine hemoglobin during spray-drying and powder storage by combining chelating and reducing agents.

This work focuses on the effects of adding a chelating agent - such as nicotinic acid (NA, 2% w/v) or nicotinamide (Nam, 2.5% w/v) - along with glucose as a reducing agent (G, 10% w/v) to fresh porcine hemoglobin in order to stabilize its red color during spray-drying and powder storage at room temperature. Correlations between the CIELAB color parameters and the relative percentages of the different hemoglobin derivatives (liganded and deliganded ferrohemoglobin, and methemoglobin) were analyzed. The results indicate that, although little effects could be observed for any of the combined treatments on fresh hemoglobin, they were effective against pigment autoxidation during dehydration and subsequent storage. From the results, it can also be concluded that glucose was the main contributor to the color stabilization of the hemoglobin powder, probably due to its high water retention capacity.

Effectiveness of high pressure processing on the hygienic and technological quality of porcine plasma from biopreserved blood

The effects of a high hydrostatic pressure (HHP) treatment (450MPa, 15min at 20°C) on both the microbiological quality and the functional properties of plasma from biopreserved porcine blood were evaluated. Blood was inoculated with Enterococcus raffinosus-PS99 (10(7)ufcmL(-1)) and stored at 5°C. After 72-h storage, bacterial counts in inoculated samples decreased by 52, 70, 81 and more than 99% for coliforms, Pseudomonas spp, hemolytic and proteolytic bacteria, respectively. Counts of these bacterial groups were undetectable in the final product after pressurization, whereas total lactic acid bacteria were detected at levels up to 10(2)ufcmL(-1). Gelling, foaming and emulsifying properties of the plasma proteins were not noticeably affected by HHP. The results show that it is possible to obtain high-quality and microbiologically stable blood derivatives as functional ingredients, by combining biopreservation and HHP.

Low-salt porcine serum concentrate as functional ingredient in frankfurters.

The objective was to assay the use of serum from porcine blood as functional ingredient in frankfurter production. Three pilot productions of sausages were carried out to compare serum containing frankfurters to sausages based on a standard commercial formula that included caseinate and polyphosphate. Both products were very similar for proximate composition, water holding capacity, cooking and purge losses, instrumental texture, and microstructure. The sensory descriptive profile and the overall acceptance were also comparatively evaluated. Although significantly higher values for the animal taste and odour attributes of sausages with serum compared to control ones were obtained, the differences were lower than those reported in a previous study using whole plasma. Thus, ultrafiltration could be useful to reduce animal off-flavour in blood-based protein ingredients. Moreover, overall acceptance did not significantly differ between the two types of products, being 6.7 and 6.5, for control and test sausages respectively.

Nanofibrillated Cellulose as Functional Ingredient in Emulsion-Type Meat Products

The objective of this work was to introduce nanofibrillated cellulose (NFC) in the formulation of cooked emulsion-type sausages with the aim of assessing its feasibility to assume the role or compensate the lack of some conventional functional ingredients, such as polyphosphates, maize starch, and sodium caseinate. For this aim, sausages based on standard commercial formula (control) including all three ingredients and sausages containing 0.5% NFC instead of phosphates and starch (NFC-1) or instead of phosphates, starch, and sodium caseinate (NFC-2) were produced and characterized. In NFC-1 samples, 0.5% nanofibrillated cellulose succeeds in replacing 0.5% polyphosphates and 1% starch without significantly altering the composition, nor negatively affecting the fat and water retention properties, neither of the raw batter or the cooked sausages. However, less stable meat batters and sausages with significantly reduced water-holding capacity were obtained when 1.5% sodium caseinate, in addition to phosphates and starch, was also removed (NFC-2). Nevertheless, results were hopeful enough to encourage further optimization studies, using several NFC concentrations and/or cellulose with different nanofibrillation degrees, in order to clarify whether it is possible to successfully replace also non-meat proteins in cooked emulsion-type sausages.