Valorisation of pork by-products to obtain antioxidant and antihypertensive peptides.

The porcine liver could be used for the extraction of zinc-protoporphyrin (ZnPP) as a natural red meat pigment. During the autolysis process, porcine liver homogenates was incubated at pH 4.8 and 45 °C under anaerobic conditions to obtain insoluble ZnPP. After incubation, the homogenates were readjusted at pH 4.8, and at pH 7.5 before being centrifuged at 5500 × g for 20 min at 4 °C and the resulting supernatant were compared with the obtained at pH 4.8 at the beginning of the incubation. The molecular weight distributions of the porcine liver fractions at both pHs were very similar, however, eight essential amino acids were more abundant in fractions obtained at pH 4.8. Regarding the ORAC assay, porcine liver protein fraction at pH 4.8 showed the highest antioxidant capacity but antihypertensive inhibition was similar for both pHs. Peptides with strong bioactivity potential from aldehyde dehydrogenase, lactoylglutathione lyase, SEC14-like protein 3 and others were identified. The findings have demonstrated the potential of the porcine liver to extract natural pigments and bioactive peptides.

Physicochemical and Techno-Functional Properties of Dried and Defatted Porcine Liver.

Porcine liver has a high nutritional value and is rich in proteins, minerals, and vitamins, making it an interesting co-product to alleviate the growing global demand for protein. The objective of this study was to analyze how the drying and defatting processes of porcine liver affect the physicochemical and techno-functional properties of its proteins. Two drying temperatures (40 and 70 °C) were studied, and dried samples were defatted using organic solvents. The drying process turned out to be an effective method for the stabilization of the protein fraction; however, when the drying temperature was high (70 °C), greater protein degradation was found compared to drying at a moderate temperature (40 °C). Regarding the defatting stage, it contributed to an improvement in certain techno-functional properties of the liver proteins, such as the foaming capacity (the average of the dried and defatted samples was 397% higher than the dried samples), with the degree of foaming stability in the liver dried at 40 °C and defatted being the highest (13.76 min). Moreover, the emulsifying capacity of the different treatments was not found to vary significantly (p > 0.05). Therefore, the conditions of the drying and defatting processes conducted prior to the extraction of liver proteins must be properly adjusted to maximize the stability, quality, and techno-functional properties of the proteins.

Surimi-like protein ingredient from porcine spleen as lean meat replacer in emulsion-type sausages.

The aim of this work was to assess the influence of a porcine spleen surimi-like protein ingredient as pork meat replacer in emulsified cooked meat products (frankfurter-type sausages). The effects of the addition of porcine spleen protein isolate (SPI) in substitution of lean meat at concentrations of 5%, 10% and 15% on the physicochemical characteristics, microstructure, textural, and sensorial properties of the sausages were investigated. The addition of SPI did not affect the emulsion stability of raw meat batters nor the proximate composition of the cooked sausages, provided that sausages are formulated considering the differences in protein and fat content between pork meat and spleen protein fraction. Results showed that SPI was successfully applied as a meat replacer up to 15% of substitution level without producing significant modification on the physicochemical and techno-functional properties (water holding capacity and instrumental texture) of sausages. Meat replacement with SPI resulted in the formation of a stable and homogeneous protein gel network. Moreover, there were no negative effects on the sensory attributes in the cooked sausages containing 15% SPI as compared to the control ones. Therefore, the results of this study confirm that SPI up to 15% can be successfully used as a lean meat substitute in meat products.

RSM Optimization for the Recovery of Technofunctional Protein Extracts from Porcine Hearts.

Meat byproducts, such as the internal organs from slaughtered animals, are usually underutilized materials with low commercial value. The functional (emulsifying, gelling, and foaming) properties of soluble protein extracts derived from pork hearts were investigated, as well as their molecular weight distribution. A central composite design (CCD) for two process variables (pH and ionic strength of the extraction buffer) was used to foreknow the effects of the process conditions on the physicochemical characteristics and technofunctionality of the protein extracts by means of the response surface methodology (RSM). SDS-PAGE patterns of the heart protein solutions revealed multiple bands with molecular weights ranging from 15 to 220 kDa, mainly corresponding to sarcoplasmic, myofibrillar, as well as blood proteins. The best extraction conditions to obtain protein fractions with good foaming properties would correspond to acid pH (pH ≤ 5) and high salt content (2-4%). On the contrary, solutions recovered at pH > 5 with low NaCl contents were the ones showing better emulsifying properties. Regarding gelation ability, heat-induced gels were obtained from extracts at pH 6.5-8, which showed improved firmness with increasing NaCl content (2-4%). Satisfactory second-order polynomial models were obtained for all the studied response variables, which can be useful in guiding the development of functional ingredients tailored for specific uses to maximize applications.

Exposure of livestock to GM feeds: Detectability and measurement.

This review explores the possibilities to determine livestock consumption of genetically modified (GM) feeds/ingredients including detection of genetically modified organism (GMO)-related DNA or proteins in animal samples, and the documentary system that is in place for GM feeds under EU legislation. The presence and level of GMO-related DNA and proteins can generally be readily measured in feeds, using established analytical methods such as polymerase chain reaction and immuno-assays, respectively. Various technical challenges remain, such as the simultaneous detection of multiple GMOs and the identification of unauthorized GMOs for which incomplete data on the inserted DNA may exist. Given that transfer of specific GMO-related DNA or protein from consumed feed to the animal had seldom been observed, this cannot serve as an indicator of the individual animal's prior exposure to GM feeds. To explore whether common practices, information exchange and the specific GM feed traceability system in the EU would allow to record GM feed consumption, the dairy chain in Catalonia, where GM maize is widely grown, was taken as an example. It was thus found that this system would neither enable determination of an animal's consumption of specific GM crops, nor would it allow for quantitation of the exposure.

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.

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.

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.

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.

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 blood's 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.