Months Of Freezing Research Articles

Meat quality of Argentinean “Camperos” chicken enhanced in omega-3 and omega-9 fatty acids

Five diets were assessed with the aim of increasing oleic fatty acid and omega-3 polyunsaturated fatty acid content in ‘campero’ poultry meat and evaluating their influence on sensory attributes. Animals from treatment 1 (T1) were confined and fed with corn/soybean diet; in T2, animals were fed with a corn/soybean mix with free access to pasture; T3 diet had high oleic sunflower seeds (HOSS) and linseeds with access to pasture; T4 diet was similar to T2 with free access to chicory instead of pasture and T5 diet was similar to T3 with free access to chicory instead of pasture. Linseeds and HOSS supplementation significantly increased the fatty acids profile, regardless of forage supply. T3 MUFA content was significantly higher than in the other treatments. Due to the high presence of omega-3 PUFA in linseeds and HOSS treatments (T3 and T5), meat omega-6/omega-3 ratio decreased from 9 to 4. The presence of off-flavours was not influenced by diets but there was an interaction between portion and storage conditions. ‘Poultry meat’ aroma was only influenced by the storage conditions, being slight after 4 months of freezing, while presence of off-aromas was affected by diets. We conclude that it is possible to produce ‘campero’ poultry meat with enhanced omega-3 and omega-9 content and a low omega-6/omega-3 ratio using diets based on linseed and HOSS, without any important change in sensory properties.

Storage Stability of Two Liquid Formulations of Bacillus thuringiensis subsp. israelensis and Effect of Freezing Over Time

Over the last two decades, many tests have been performed in the field to investigate the behaviour (persistence, carry, loss of activity, etc.) of different Bacillus thuringiensis subsp. israelensis ( Bti ) formulations. Depending on the experimental protocols, a single container of a formulation could be used more than once over time and field samples containing Bti may have to be frozen to preserve them for bioassays to be performed later. Thus, it is necessary to know how long a formulation could keep its level of efficacy and also the effects of time on frozen samples. Our results showed that the efficacy of two commercial liquid formulations of Bti (Teknar HP-D and Vectobac 1200L) when tested against Aedes triseriatus behaved differently over time when kept at room temperature. Teknar HP-D remained stable for the first two years and its LC 50 increased by 20% the third year. For Vectobac 1200L, although its larvicidal activity was better than that of Teknar HP-D every year, there was an increase in LC 50 by 22% the second year and by another 20% the third year for a total loss of activity of 46% over the three-year study. The efficacy of suspensions made with both formulations was greatly affected by freezing and the loss of efficacy increased over time. About half of the efficacy of Teknar HP-D was lost after one week of freezing and stayed at that level for three months, while with Vectobac 1200L, no significant effect of freezing was seen after one month, when compared to fresh material. However, both products showed similar efficacy after three or six months of freezing. Overall, the LC 50 s of both products had increased by a factor of about 2.5 after six months of freezing.

Monitoring of the vitamin C content of frozen green beans and Padrón peppers by HPLC

Abstract: HPLC (using a C18 column, water at pH 2E2 as mobile phase, and UVdetection) was used to monitor the vitamin C content of deep-frozen ([22iC)green beans and Padro“ n peppers over 12 months. Unblanched beans andpeppers lost P97% of their vitamin C within 1 month of freezing, whether or notthey were contained in bags sealed under vacuum. Blanching reduced the beansIvitamin C content by 28%, but limited further decreases to between 3 (vacuumsealed) and 10% (no vacuum) in 12 months. These results conÐrm the utility ofblanching in the preservation of vegetables by deep-freezing. 1998 SCI.(J Sci Food Agric 76, 477E480 (1998)Key words: deep-freezing; HPLC; ascorbic acid; green beans; peppers INTRODUCTIONHumans are among the few mammals incapable of bio-synthesis of ascorbic acid, or vitamin C. The amount ofthis vitamin in foodstu†s should therefore be carefullymonitored with a view to avoiding deÐciency, which inextreme cases causes scurvy and, moreover, leads toreduced resistance to infection (Anderson et al 1987).Vitamin C is almost exclusively found in fruit andvegetables although the amount present varies amongvarieties (Morrison 1975) according to factors such asthe stage of development and size of the produce(Selman and Rolfe 1982), and the time between harvest-ing and processing (Kozar et al 1988). This variation isreNected in the diversity of vitamin C content reportedin the literature for fresh produce.The seasonality and high perishability of fruit andvegetables provides opportunity to apply preservation

Preliminary characterization of a placental factor inhibiting breathing in fetal sheep.

Previous studies have revealed a placental extract that inhibits breathing in fetal sheep. In the present study of 29 chronically instrumented sheep at 132+/-1 days of gestation, infusion of the 1-10 kDa extract inhibited breathing in 76% of the experiments whereas Krebs' solution inhibited it in 24%. It retained this activity after 6 months of freezing, after lyophilization, and upon lowering the pH during purification from 8.0 to 4.0, but it inhibited breathing in only 35% when the pH was lowered to 2.0. A significant dose-dependent effect was observed from a 16-fold dilution to a 4-fold concentration. Treatment of the extract with proteinase K or boiling reduced the activity to 30% or 26% inhibition, respectively. The activity was not adsorbed to an ion-exchange column at pH 7.0 or 8.0, but it was at pH 9.0 and it eluted with increasing NaCl concentrations. On a polyacrylamide gel the activity was eluted at a K(av) of 0.66 (82% inhibition), corresponding to between 2.5 and 4.5 kDa. These findings suggest that a peptide produced by the placenta, with a molecular mass between 2.5 and 4.5 kDa, inhibits fetal breathing.

Development and testing of a vaccine for the prevention of infectious bovine keratoconjunctivitis

We have purified, concentrated and stabilized the protein cytotoxin from Moraxella bovis. The toxin is concentrated on a filter with a 500,000 kDa molecular weight cut off. Small proteins are removed by extensive diafiltration on the same filter. The cytotoxin is concentrated approximately 500 fold, and remains active after 5 months of freezing. A vaccine trial for toxicity and efficacy were performed.

Measurement of serum lecithin, lysolecithin, and sphingomyelin by a simplified chromatographic technique.

Abstract A comparatively rapid procedure for quantitating small amounts of the major phospholipid components of serum by use of silicic acid paper chromatography is described in detail. Recoveries of mixtures of pure lecithin, lysolecithin, and sphingomyelin were about 90 per cent. A variety of anticoagulants, including heparin, were found to have little effect on phophatide values. In 10 normal subjects the average lecithin phosphorus concentration was 66 per cent, lysolecithin phosphorus 9 per cent, and sphingomyelin phosphorus 23 per cent of the total phospholipid phosphorus applied. These values are similar to those previously reported with column or paper chromatographic techniques. Prolonged freezing of serum with intermittent brief thawing resulted in the conversion of approximately 9 per cent of the lecithin to lysolecithin, the converted portion representing 6 per cent of the total phospholipid phosphorus. Short periods of freezing had relatively little effect. No significant changes were seen in any of the components after one week of freezing. No more than 3 per cent of the lecithin phosphorus was lost after one month of freezing.