Effect of Date Palm Coproducts and Annatto Extract on Lipid Oxidation and Microbial Quality in a Pork Liver Pâté

Dates are an interesting source of bioactive compounds, and coproducts from the date industry are of potential use in the manufacturing of meat products. In the present research, spreadable pork liver pâtés were made using fresh date coproducts (2.5% and 7.5%) as a potential functional ingredient and an ethanolic annatto extract (128 mg/kg) as colorant. The effect of these 2 ingredients on the lipid oxidation and microbial quality of the pâtés was assessed during 21 d of storage. The pâtés containing 7.5% date paste were seen to have the highest content of phenolic compounds during storage. The combination of 2.5% date paste and annatto protected pâtés against lipid oxidation throughout the 21 d of storage, thiobarbituric acid‐reactive substances values being 0.47 mg MDA/kg at the end of this period, while other combinations increased oxidation compared to the control pâté. The control and those made with 2.5% date paste alone showed the highest counts of mesophilic aerobic bacteria, while the addition of annatto and/or 7.5% date paste reduced this count. The results suggest that a combination of both ingredients is necessary to reduce oxidation and microbial growth, but whereas the concentration of 2.5% is more appropriate to reduce oxidation, the combination with 7.5% date paste reduces the microbial counts. Both ingredients could have an opportunity of valorization in the meat industry for improving the quality.     

Volatile compounds of experimental liver pâté from pigs fed conjugated linoleic acid in combination with monounsaturated fatty acids

BACKGROUND: Feeding conjugated linoleic acid (CLA) to pigs leads to CLA‐enriched meat products, which are of current interest owing to the potential health properties of CLA. However, dietary CLA increases the ratio of saturated to monounsaturated fatty acids (MUFA) in pig tissues. Combining CLA with high MUFA levels in pig diets may counteract this effect. Owing to the modification of fatty acid composition, variation in the volatile profile of derived meat products might be expected. The aim of the present work was to study the volatile profile, and its change during storage, of experimental liver pâté manufactured from pigs fed different levels of CLA and MUFA. RESULTS: Regardless of the CLA or MUFA level, 98 compounds were identified. Lower area units were observed for most branched aldehydes, ketones and alcohols and some furans, sulfur compounds and nitrogen compounds with increasing CLA and MUFA contents. Levels of nonanal, propan‐2‐one, dodecane, 2‐pentylfuran and ethylbenzene were higher in CLA pâtes. The effect of experimental diets on the change in volatiles during storage was not significant. CONCLUSION: Supplementation of pig diets with CLA isomers in combination with low or high MUFA levels seems to have a significant effect on the volatile profile of pork liver pâté. Copyright © 2009 Society of Chemical Industry     

The effect of long‐term storage on amino acid content of ready‐to‐eat entrées

The effect of 24‐month storage at three different temperatures (6 ± 2 °C, 26 ± 2 °C, 37 ± 2 °C) on quality of three types of ready‐to‐eat entrées (MRE) was evaluated by means of amino acid, ammonia, moisture and crude protein contents. Spicy risotto, Pork meat with carrots and potatoes and Pork goulash with pasta, that are included into the Czech combat rations, were selected for the experiment. During storage, all the explored samples did not significantly differ in moisture and crude protein content. Higher losses of amino acids (e.g. sulphuric amino acids, lysine, leucine) were detected with the increasing storage time and temperature. Growing losses of amino acids resulted in rising ammonia content as a product of amino acid degradation process. The biological value expressed by essential amino acid index declined with higher temperature and longer time of storage. The dependence of amino acid losses on moisture content was observed, too.     

Self‐segmenting of rennet‐induced milk gel in cheesemaking tank

The phenomenon of self‐segmenting of milk gel in an open‐type cheesemaking tank is described. It is shown that the self‐segmenting of the gel is caused by the thermo‐gravitational convection of Rayleigh–Bénard and the thermo‐capillary convection of Bénard–Marangoni. A mechanism for the self‐segmenting of milk gel, in which the important role of fat globules in this process has been noted, is proposed. It is noted that the self‐segmenting of the milk gel can cause some defects in the finished cheese: uneven texture and colour disorder.     

Partial replacement of pork fat by conjugated linoleic acid and/or olive oil in liver pâtés: Effect on physicochemical characteristics and oxidative stability

The effect of replacing pork fat in liver pâtés by an enriched conjugated linoleic acid oil (CLA-pâté), olive oil (OO-pâté), or the combination of both type of oils (CLA + OO-pâté) on the fatty acid profile, lipid oxidative stability, consistency and emulsion stability was studied and compared with a traditional liver pâté (C-pâté). Pâtés were analyzed at days 1, 6, 21 and 71 of refrigerated storage (4 °C). A enrichment in CLA was attained in CLA-pâté and CLA + OO-pâté. CLA-pâtés had the highest content in polyunsaturated fatty acids (PUFA) (p < 0.05) due to their content in CLA. A lower content in saturated fatty acids was achieved when using OO or CLA in pâtés (p < 0.05). OO-pâtés showed the highest levels of monounsaturated fatty acids (MUFA) (p < 0.05). No changes in the fatty acid profile and in lipid oxidation (mg malondialdehyde per kg of sample) throughout the storage of the products were found. Lower consistency and emulsion stability were obtained when using CLA or OO in the formulation. Consistency values (in N/cm²) tended to increase and emulsion stability to decrease throughout the storage in CLA or OO enriched pâtés.     

Use of banana purée from three indigenous Thai cultivars as food matrices for probiotics and application in bio‐set‐type yoghurt production

This research studied the use of banana purée from three indigenous Thai cultivars (Kluai Hom Thong, Kluai Namwa and Kluai Khai) as probiotic carrying agents in food and application in bio‐set‐type yoghurt. Kluai Khai purée had promising indication of prebiotic activity on Lactobacillus paracasei Lpc‐37 with the highest probiotic activity score. When Lpc‐37 cell was incorporated into Kluai Khai purée, its cell counts increased by 0.8 log CFU g^?1 and it adhered to purée, as seen by the proliferating cells. Therefore, Kluai Khai purée mixed with Lpc‐37 was selected for the production of bio‐set‐type yoghurt. The results showed that viable cells increased more than 0.8 log CFU g^?1 during storage. This study reflected the achievement of using Kluai Khai purée as food matrix for carrying ‘active probiotic cells’ in bio‐yoghurt production. This methodologically developed prototype could be an interesting alternative for value adding of indigenous fruits.     

Modulatory effects of yerba maté (Ilex paraguariensis) on the PI3K‐AKT signaling pathway

The aim of this study was to evaluate the effects of yerba maté (YM) extract on the phosphatidylinositol 3‐kinase (PI3K)‐AKT signaling pathway in vivo. The mice were introduced to either standard‐ or high‐fat diet (HFD). After 8 weeks on an HFD, mice were randomly assigned to one of the two treatment conditions, water or yerba maté extract at 1.0 g/kg. After treatment, glucose blood level and hepatic insulin response were evaluated. Liver tissue was examined to determine the mRNA levels using the PI3K‐AKT PCR array. The nuclear translocation of forkhead box O1 (FOXO1) was determined by an electrophoretic mobility‐shift assay. Our data demonstrated that yerba maté extract significantly decreased the final body weight, glucose blood levels, and insulin resistance of mice. Molecular analysis demonstrated that an HFD downregulated Akt2, Irs1, Irs2, Pi3kca, Pi3kcg, and Pdk1; after yerba maté treatment, the levels of those genes returned to baseline. In addition, an HFD upregulated Pepck and G6pc and increased FOXO1 nuclear translocation. The intervention downregulated these genes by decreasing FOXO1 nuclear translocation. The results obtained demonstrate for the first time the specific action of yerba maté on the PI3K‐AKT pathway, which contributed to the observed improvement in hepatic insulin signaling.     

Influence of fat content on physico-chemical and oxidative stability of foal liver pâté

The effect of fat content on physico-chemical properties and lipid and protein stability of foal liver pâté was studied. For this purpose, two batches (10 units per batch) of foal liver pâté with different pork back fat content [30% (30F) and 40% (40F)] were manufactured.     

Sage and rosemary essential oils versus BHT for the inhibition of lipid oxidative reactions in liver pâté

The antioxidant effect of two plant essential oils (sage and rosemary essential oils) and one synthetic antioxidant (BHT) on refrigerated stored liver pâté (4 °C/90 days) was evaluated. Pâtés with no added antioxidants were used as controls. Liver pâtés were analysed for the amount of polyunsaturated fatty acids (PUFA), thiobarbituric acid reactive substances (TBA-RS) numbers, and lipid-derived volatiles at days 0, 30, 60 and 90 of refrigerated storage. The amount of PUFA gradually decreased during refrigerated storage of porcine liver pâtés with this decrease being significantly greater (P<0.05) in control and BHT pâtés than in those with added essential oils. Consistently, the increase of TBA-RS numbers during refrigerated storage of liver pâtés was significantly higher in control pâtés than in the treated counterparts. At days 60 and 90, TBA-RS numbers in treated pâtés were significantly smaller (P<0.05) than in the control counterparts. Headspace solid-phase microextraction (HS-SPME) successfully isolated recognized indicators of lipid decomposition (i.e. hexanal, nonanal, hexan-1-ol, oct-1-en-3-ol, deca-(E,Z)-2,4-dienal) from liver pâtés whereas some other volatiles analysed are typical contributors to the overall off-flavour of oxidized liver (i.e. hept-(Z)-4-enal, non-(E)-2-enal, nona-(E,E)-2,4-dienal). The addition of antioxidants significantly (P<0.05) reduced the total amount of lipid-derived volatiles isolated from liver pâtés HS. Plant essential oils inhibited oxidative deterioration of liver pâtés to a higher extent than BHT did.     

In vitro antioxidant synergism and antagonism between food extracts can lead to similar activities in H2O2‐induced cell death,caspase‐3 and MMP‐2 activities in H9c2 cells

BACKGROUND: The cardio‐health‐promoting activity of some foods may be due to their specific antioxidant content. The antioxidant activity of a mixture of plant extracts has been shown to differ from the activity of the individual extracts. As a result, the activity of the mixture can be described as synergistic, antagonistic or additive. This in vitro study evaluated the relationship between the in vitro antioxidant capacity of mixtures and their bioactivity when cardiomyocytes (H9c2) were challenged with H₂O₂. RESULTS: A mixture of raspberry and adzuki bean extracts produced a synergistic response and a mixture of broccoli and soybean extracts produced an antagonistic response in chemical‐based antioxidant assays. When these extracts were tested in cell cultures, individually and in mixtures, the mixture of raspberry and adzuki bean protected the cardiomyocytes from H₂O₂‐induced cell damage significantly better than the individual extracts. Conversely, the mixture of broccoli and soybean extracts was less effective in protecting H9c2 cells. The synergistic and antagonistic effects of the mixtures in protecting cell damage were brought about by enhanced or reduced ability in attenuating caspase‐3 and matrix metalloproteinase‐2 activities elevated by H₂O₂. CONCLUSION: Food mixtures with synergistic antioxidant activity and protective property against reactive oxygen species‐induced cell death can potentially be incorporated into novel functional foods or beverages with optimum health benefit. The antagonistic effect of food mixtures can be a health concern and thus should be avoided. Copyright © 2012 Society of Chemical Industry