Brian Wilkinson

Preliminary investigation of the effects of low-level dietary inclusion of fragrant essential oils and oleoresins on pig performance and pork quality

Since the tissue characteristics of monogastric species are readily influenced by the composition of the feeds they consume, the objectives of this preliminary study were to assess the performance of finisher pigs on diets containing 0.05% of essential oils or oleoresins of rosemary, garlic, oregano, or ginger, and to determine the effect of these diets on pork quality. The pigs preferred the garlic-treated diet, and feed intake and average daily gain were significantly increased although no difference in feed efficiency was observed. Carcass and meat quality attributes were unchanged by dietary treatment, although a tendency towards reduction of lipid oxidation was noted in oregano-fed pork. Sensory panelists were unable to detect a flavour/aroma difference between treated and control pork. These results indicate that a higher level of dietary supplementation may be required in order to effect observable differences in pork characteristics.

The effect of modified atmosphere packaging with carbon monoxide on the storage quality of master-packaged fresh pork

Modified atmosphere packaging with carbon dioxide is effective for prolonging shelf-life of fresh meat. Addition of carbon monoxide to the system provides the advantage of enhancing meat colour. The study objective was to determine the effect of CO(2)-MAP+0.4% CO, vs. 100% CO(2)-MAP, on the bacteriology and colour of retail-ready fresh pork stored for 8 weeks in a master-package system. Total plate counts were not affected and listeria was present on meat from both treatments. Colour was enhanced with the inclusion of CO, while no effect on lipid oxidation was observed. Use of CO in MAP provides sufficient storage life and product colour quality to permit shipment of fresh pork to distant markets. However, given the stable fresh colour of CO-treated meat and the lack of inhibition of pathogen growth by CO, there is concern that CO-MAP under certain conditions may pose a food safety risk.

Cooking temperature effects on the forms of iron and levels of several other compounds in beef semitendinosus muscle

The influence of final cooked temperature on the form of iron present and on the concentration of taurine, carnosine, coenzyme Q(10) and creatine was investigated in surface and inner parts of 30-mm thick steaks from beef semitendinosus muscle (n=6). The use of a fast, dry-heat cooking method with a Silex clam cooker (set at 200 °C) led to cooking times ranging from 5.6 to 8.6 min for final internal temperatures of 60 and 85 °C, respectively. The proportion of iron as soluble haem iron decreased from 65% in uncooked meat to 22% when cooked to 60 °C and then decreased more gradually with increases in final cooked temperature. The proportion of insoluble haem iron increased in a reciprocal manner, while changes in the proportions of soluble and insoluble non-haem iron were relatively small, but increases in the percentage of insoluble non-haem iron with increasing final temperature were significant (P<0.01). Changes in the forms of iron with cooking generally took place more rapidly in surface samples than inner samples. On a dry-matter basis, concentrations of taurine, carnosine, coenzyme Q(10), and creatine all decreased with cooking, but the decreases were greatest for taurine and creatine. Losses of creatine were at least partly due to conversion to creatinine, and, along with the other compounds, probably included some loss in cooking juices. It is concluded that despite these changes with cooking, beef semitendinosus muscle remains a good source of iron and a useful source of the potentially bioactive compounds taurine, carnosine, coenzyme Q(10) and creatine.

The influence of diets supplemented with conjugated linoleic acid, selenium, and vitamin E, with or without animal protein, on the composition of pork from female pigs

The objective of this study was to evaluate the effect of dietary manipulations on the fatty acid composition, Se content, and vitamin E content of pork. Sixty Duroc-cross gilts were randomly allocated at weaning to 1 of 4 dietary treatment groups (n = 15 per group). The 4 experimental diets were based on animal plus plant components or plant components only, with or without the inclusion of a dietary supplement (0.614%) containing CLA, Se, and vitamin E. The growth performance to approximately 100 kg of BW was similar with diets containing animal plus plant components or only plant components. Growth was also similar when either of these diets included the supplement. Inclusion of the supplement led to expected increases in Se and vitamin E contents (P < 0.001) of the LM. The differences found in the fatty acid profile of the lipid in LM, loin subcutaneous fat, and the belly cut (pork belly) between the groups with and without animal components in their diets largely reflected differences in the diet composition. Inclusion of the supplement led to greater CLA contents in all 3 tissues (P < 0.001), and also to lower contents of oleic acid (P < 0.001) and greater contents of stearic acid (P < 0.05), possibly due to an inhibition of stearoyl-CoA desaturase enzyme. The supplement also led to an increase in LM intramuscular fat (P < 0.05), but did not affect P2 fat depths (65 mm lateral to the midline of the spine at the last rib; mean depth of 11.8 mm). It is concluded that changing from a part animal component diet to an all plant diet will not change the growth performance of pigs but changes in the fatty acid profile of pork are likely to occur. It is further concluded that the nutritional value of pork may be successfully enhanced by simultaneously supplementing the diet with CLA, selenium, and vitamin E.

1,5-glucono-δ-lactone-induced gelation of myofibrillar protein at chilled temperatures

In this study 1,5-glucono-δ-lactone was used to achieve acid-induced gelation of myofibrillar proteins at 4 °C. The characteristics of the myofibrillar gels were investigated by measuring Youngs modulus and springiness. The effects of addition of sodium chloride and tetrasodium pyrophosphate on gel characteristics were also studied. Sodium chloride increased the Youngs modulus of myofibrillar protein gels in the presence and absence of 1,5-glucono-δ-lactone, while tetrasodium pyrophosphate had no observable effect on the gels until the pH decreased to 4.1, when the Youngs modulus was enhanced.

Chemical composition characteristics of the longissimus and semimembranosus muscles for pigs from New Zealand and Singapore

A range of composition characteristics of the longissimus (LL) and semimembranosus (SM) muscles were compared between pigs raised in intensive and extensive production systems in New Zealand (NZ), and pigs raised in an intensive system in Indonesia for supply to the Singapore market (n=8/group). Ultimate pH was slightly higher for the Singaporean LL muscles (P<0.05), while LL muscle of the NZ extensive group was redder (higher a(∗) values) and contained more fat (P<0.05). Muscle iron levels were highest for the NZ extensive group and lowest for a lighter group within the Singapore pigs (P<0.05). Differences in fatty acid concentrations, which were also measured in a sample of the belly cut, could largely be attributed to the effects of diet, with higher levels of alpha linolenic acid for the NZ extensive group (P<0.05) due to linseed in the diet, and much higher levels of linoleic acid and the P:S ratio for the Singapore group (P<0.05). Some statistically significant differences in amino acid concentrations were shown between muscles and groups, but they were not large. With respect to compounds with potential bioactive properties, coenzyme Q10, and taurine levels were higher in pork from NZ pigs, and carnosine levels were highest for the NZ intensive group (P<0.05). The LL muscle contained more coenzyme Q10 and taurine, but less carnosine than the SM muscle (P<0.001). It is concluded that some of these composition differences in the pork from the muscles and groups compared may be of commercial importance, but several are likely to have been due to dietary or weight differences.

Ovine antimicrobial peptides: new products from an age-old industry

Antimicrobial peptides are part of the natural immune system of all plants and animals. This review focusses on ovine antimicrobial peptides because of the importance of the lamb industry in Australasia. The epithelial tissue β-defensins, respiratory surfactant-associated anionic peptides (SAAPs), and neutrophil cathelicidins are all described, and possible applications for these peptides are looked at, including use in ovine medicine, as biopreservatives, and as human therapeutics.

The production of pork with garlic flavour notes using garlic essential oil

Garlic essential oil (GEO) added directly to pork mince or to the diet of pigs was evaluated for its effectiveness in masking undesirable mutton flavour. Pork was from 31 female pigs (Duroc x (Large White x Landrace)) grown on diets containing either animal-plus-plant products (AP diet) or plant products only (P diet) with four levels of GEO: 0, 0.55, 1.44 and 1.84 g/kg feed and 0, 0.55, 1.44 and 2.15 g/kg feed in the AP and P diet, respectively. Garlic flavour increased and mutton flavour decreased in pork from pigs that consumed more than about 150 g and 220 g of GEO in P and AP diets, respectively over the 57-day feeding period. The garlic flavour was stronger and the mutton flavour less intense for pork from pigs on the P diet. When GEO was added to pork mince at 125 ppm, it significantly reduced mutton flavour.

Effect of lipid type on growth performance, meat quality and the content of long chain n-3 fatty acids in pork meat.

The aim of the present study was to produce pork with enhanced nutritive value for humans, both in terms of fatty acid profile (mainly long chain n-3 fatty acids by feeding fish oil) and selenium. Forty-eight female pigs were allocated to one of six treatment groups: animal by-products and plant feedstuffs with tallow, plant feedstuffs with a blend of soybean oil and linseed oil with or without a supplement (CLA, selenium, vitamin E and vitamin C), plant feedstuffs with tallow and supplement, plant feedstuffs with fish oil and supplement. The diets containing the fish oil were fed up to either 49 days or 28 days before slaughter. The dietary treatments had no significant effects on growth performance, carcass characteristics and meat quality. When fish oil was included in the diet, higher levels of EPA, DPA and DHA were measured in the subcutaneous fat (up to 3.74%).

The retention and recovery of amino acids from pork longissimus muscle following cooking to either 60°C or 75°C.

Samples of pork longissimus muscle (n=16) cooked to either 60°C or 75°C in a water bath for 90 min were assessed for amino acid composition. Recovery of protein in the cooked meat plus the cooking juice was >93% and was slightly higher at 60°C (P=0.031), but retention in the meat was only 89% and 82% for the lower and higher temperatures (P<0.0001). Individual amino acids varied in recovery and retention with retention being particularly low for taurine and histidine. The balance of indispensable amino acids was less than ideal, with leucine and valine being the limiting amino acids by about 30% for both raw and cooked pork. Cooking had no detrimental effect on amino acid balance. Some examples of small effects of genotype and sex on amino acid composition of pork were shown.