Recent trends in the fatty acid composition of German sunflower margarines,shortenings and cooking fats with emphasis on individual C16 : 1, C18 : 1, C18 : 2, C18 : 3 and C20 : 1trans isomers

In some countries the content oftransfatty acids (TFA) in margarines has strongly decreased as a result of the continuous discussion on their disadvantages regarding aspects of nutritional physiology. However, still in 1994 almost 1/3 of total fatty acids in part of German sunflower margarines, shortenings and cooking fats comprised these unfavourable TFA. In the present study the main interest was laid ontrans‐C16 : 1,trans‐C18 : 1,trans‐C20 : 1,trans‐C18 : 2 and trans‐C18 : 3 fatty acids and particularly their individual isomers, as negative metabolic activity of TFA possibly might only be attributable to certain isomers. By combining argentation thin‐layer chromatography with gas chromatography using a 100‐m capillary column (CP‐Sil 88) trans fatty acid contents were determined in nearly all German brands of sunflower margarines (SFM; n = 9) and of cooking fats and shortenings (CFS; n = 10). Concerning the above‐mentioned groups of isomers mean TFA contents of 0.01, 4.88, 0.00, 0.45 and 0.03% for SFM as well as of 0.01, 5.02, 0.03, 0.70 and 0.17% for CFS were established, respectively. The re‐evaluation of samples from 1994 and 1996 exhibited that the total TFA content (sum of all mentioned isomers) in SFM decreased from 21.77% (range: 13.78–26.29; n = 11) to 5.37% (1.98–6.15%; n = 9) between 1994 and 1999. Also the total TFA content in CFS on average strongly decreased from 11.77% (0.08–33.63; n = 16) in 1994 and 12.52% (1.61–26.79%; n = 7) in 1996 to 5.91% (0.43–19.72%; n = 10) in 1999. However, even the newest CFS samples partly exhibited relative high TFA contents. In addition to the total TFA contents all positional isomers of trans‐C18 : 1,trans‐C18 : 2 and trans‐C18 : 3 in SFM and CFS were quantified and compared between different years. The conjugated linoleic acid (cis Δ9,trans Δ11) occurred only in small amounts of 0.03% and 0.02% in current SFM and CFS.     

Photopyroelectric observation of melting in valeric (C5 : 0), linoleic (C18 : 2), linolenic (C18 : 3) and tricosanoic (C23 : 0) free fatty acids

Photopyroelectric (PPE) study of some saturated (C5 : 0, and C23 : 0) and unsaturated (C18 : 2 and C18 : 3) free fatty acids was performed in a temperature range that included their melting points. The standard PPE configuration was used consistently during the experiment; the special PPE case requests thermally thick sample and sensor and optically opaque sample. For those fatty acids for which literature data on volume-specific heat were available (C18 : 2, C18 : 3), the behaviour around the melting point of all static and dynamic thermal parameters (specific heat, thermal conductivity, diffusivity and effusivity) was obtained. Since no data for volume-specific heat of C5 : 0 and C23 : 0 were found in the literature, only the temperature behaviour of the thermal diffusivity was obtained for these specimens. © 1998 Society of Chemical Industry     

Quality changes in soup from deboned chicken frames at refrigerated (4 ± 1 °C) and frozen (−18 ± 1 °C) storage

Chicken soup was made from the broth collected after the pressure cooking of deboned chicken frames (bones). The quality of stored chicken soup (S1) was compared with the soup prepared from the stored chicken broth (S2) at refrigerated (4 ± 1 °C) and frozen (−18 ± 1 °C) storage up to 12 and 90 days, respectively. Thiobarbituric acid reactive substances values and microbial counts were significantly ( P  < 0.01) higher in stored soup (S1) compared with fresh soup (S2). Psychrotrophs and coliforms were not detected. Appearance and odour scores of broth were satisfactory throughout the storage. Sensory attributes were rated better for fresh soup (S2) made from stored broth than stored soup (S1) but all the attributes were decreased with increasing storage period. The stored soup was acceptable up to 9 and 90 days in refrigeration and frozen storage respectively, while the soup made from refrigerated stored broth was acceptable for 12 days.     

The use of nisin as a preservative in fish sausage stored at ambient (28 ± 2 °C) and refrigerated (6 ± 2 °C) temperatures

Summary The efficacy of nisin at three different concentrations, 12.5, 25 and 50 ppm, on the keeping quality of fish sausage in synthetic casing at ambient (28 ± 2 °C) and refrigerated (6 ± 2 °C) temperatures was assessed. Gel strength, expressible water content, total volatile base nitrogen, total plate count and aerobic spore counts were affected by the storage temperatures and nisin concentrations used. Fish sausage treated with 50 ppm of nisin was acceptable after storage at ambient temperature for 20–22 days compared with the control, which were acceptable only for 2 days. The keeping quality of the sausages, at refrigerated temperature, varied from 30 days in the control to 150 days in 50‐ppm nisin‐treated samples. The residual nisin decreased slowly in samples stored at refrigerated temperature, whereas, in fish sausages stored at ambient temperature, the decrease was rapid. Nisin at 50‐ppm level showed a significant effect (P ≤ 0.05) on the gel strength and overall acceptability scores both at ambient and refrigerated temperature.     

Effects of packaging systems and fat concentrations on microbiology,sensory and physical properties of ground beef stored at 4 ± 1 °C for 25 days

This study evaluated effects of modified atmosphere (MAP, 0.4% carbon monoxide [CO], 30% carbon dioxide, and 69.6% nitrogen), vacuum (VP) and polyvinyl chloride (PVC) packaging systems and fat levels (10, 20 and 30% fat) on ground beef stored at 4 ± 1 °C for 25 days for microbiology, sensory, pH, thiobarbituric acid reactive substances (TBARS), objective color, headspace and residual CO. As storage time increased, pH decreased (P < 0.05) for MAP and VP and increased (P < 0.05) for PVC. TBARS varied (P < 0.05) among MAP and VP treatments. Except for day 1, CO headspace concentrations were similar among fat concentrations, and residual CO absorption in meat increased (P < 0.05) for all MAP treatments. In all treatments, degree of lightness was similar, redness decreased and brown discoloration increased during storage. As psychrotrophic bacteria counts increased, panelists detected color and off-odor deterioration in all systems. The CO treatment had no effect on maintaining the carboxymyoglobin “cherry red” fresh meat color during meat spoilage.     

Antibiofilm effects of pomegranate peel extracts against B. cereus,B. subtilis,and E. faecalis

In this study, the antibacterial and antibiofilm properties of pomegranate (Punica granatum L.) extracts (PPLs) prepared by 10 g of pomegranate peels (PPL10) and 100 mL of different solvents (ethanol, methanol, and their acid combinations, and water) were investigated as sources of bioactive compounds against food-related bacteria. The antimicrobial activities of the extracts were measured by using agar well diffusion assay. The acid-treated extracts exhibited the highest antimicrobial activities (31–34 mm). The biofilm formations were assessed by using a microplate reader (570 nm) after crystal violet staining. The prevention and removal of bacterial biofilms were also evaluated by using extracts prepared by 5 g of initial pomegranate peel (PPL5) with the different solvents or 200 ppm chlorine solution. All PPL5 and PPL10 extracts diluted at different ratios inhibited and removed biofilms, and the highest antibiofilm effects were up to 80% by acid-treated extracts. In addition, PPL5s and PPL10s were as effective as or more effective than chlorine for the prevention of biofilms. Therefore, from an economical perspective the PPL5s could represent promising candidates as natural antibiofilm agents for food industry.     

Comparative study of antioxidant and antibacterial properties of the edible mushrooms Pleurotus levis,P. ostreatus,P. pulmonarius and P. tuber‐regium

Comparative studies of functional properties among closely related mushroom species, supported by molecular identification, standard cultivation and extraction protocols, are not well documented. We compared antioxidant and antibacterial properties of standardised hydroalcoholic extracts of four Pleurotus species (P. levis, P. ostreatus, P. pulmonarius and P. tuber‐regium). Antioxidant properties were investigated using DPPH and ABTS radical scavenging capacity, total phenolic content, β‐carotene‐linoleic and ORAC assays. Antibacterial effect was assessed using the microplate method. The functional properties of standardised mushroom extracts were different in species studied. β‐carotene–linoleic acid and ORAC assays showed high antioxidant activity, particularly in P. ostreatus. Pleurotus tuber‐regium exhibited the lowest antioxidant activity in the ORAC assay (3316.0 μmol of trolox equivalent mL^?1), but exerted the most potent bacteriostatic and bactericidal activity. Bacillus subtilis showed a high degree of susceptibility to a very low concentration (3.33 μg mL^?1) of P. levis extract. Remarkable antioxidant and antibacterial properties were found in P. levis and P. tuber‐regium compared to the other species studied that are cultivated commercially.     

Mozzarella cheese: 40 years of scientific advancement

An overview is presented of selected advances in the science of mozzarella cheese during the past 40 years. This is not intended to be a comprehensive review but rather to focus on several key milestones in the ongoing quest to understand the physicochemical basis for cheese structure and function. In keeping with the theme of this symposium, this paper highlights the pivotal role that Professor P. F. Fox had in shaping my understanding of mozzarella structure–function and the direction of my research during the past decade. The unfolding of mozzarella science has ebbed and flowed, with significant advances being made early on that were not fully recognized until much later.     

Ultrasound Enhanced Sanitizer Efficacy in Reduction of Escherichia coli O157 : H7 Population on Spinach Leaves

ABSTRACT:  The use of ultrasound to enhance the efficacy of selected sanitizers in reduction of  Escherichia coli  O157 : H7 populations on spinach was investigated. Spot-inoculated spinach samples were treated with water, chlorine, acidified sodium chlorite (ASC), peroxyacetic acid (POAA), and acidic electrolyzed water with and without ultrasound (21.2 kHz) for 2 min at room temperature. The effects of ultrasound treatment time and acoustic energy density (AED) were evaluated at an ASC concentration of 200 mg/L. The effect of ASC concentration, with a fixed AED of 200 W/L, was also examined. Microbial analysis indicated that ASC reduced  E. coli  O157 : H7 population by 2.2 log cycles over that of water wash, while the reduction from other sanitizers was about 1 log cycle. Ultrasonication significantly enhanced the reduction of  E. coli  cells on spinach for all treatments by 0.7 to 1.1 log cycle over that of washes with sanitizer alone. An increase in the ASC concentration enhanced the efficacy of the combined treatment of ASC and ultrasonication, especially at ASC concentrations of < 300 mg/L. Increasing the ultrasound treatment time from 0 to 4 min and AED from 0 to 500 W/L were both effective in increasing the effectiveness of the ASC and ultrasound combined treatments. In addition,  E. coli  O157 : H7 inoculated on the underside of spinach leaves (rough side) were more difficult to remove than those inoculated on the upper side (smooth side).     

Progressive keratoconus in patients older than 48 years

PurposeTo report cases of progressive keratoconus (KC) in patients aged ≥48 years and the successful arrest of progression using corneal cross-linking (CXL) with riboflavin and ultraviolet-A light.ObservationsFive eyes from four patients with progressive KC aged 48, 48, 51 and 54 years are reported in this case series. All eyes were followed regularly after initial diagnosis. K_max was used as an indicator of progression and KC progressed at a rate of 1.4 diopters in 6 months and 14.6 diopters in 14 months. All patients eventually received CXL, and all were aged ≥50 years at the time of the procedure. One eye required two CXL procedures to successfully stabilize the patient’s cornea.ConclusionDespite the probability of KC progression strongly declining after the age of 40 years, it never becomes zero. It is therefore advisable to continue regular follow-up corneal tomography examinations in patients with KC, even in their fifth and sixth decades of life.     

Evaluation of pre-rigor injection of beef with proteases on cooked meat volatile profile after 1 day and 21 days post-mortem storage

This research was carried out to determine the effects of pre-rigor injection of beef semimembranosus muscle with nine proteases from plant and microbial sources, on the volatile profile of cooked beef after 1 day and 21 days post-mortem (PM) storage using Solid-phase microextraction gas chromatography mass spectrometry analysis. A total of 23 aldehydes, 5 ketones, 3 furans, 8 nitrogen and sulphur compounds, 4 alkanes, 7 alcohols and 6 terpenes were detected. Eleven volatile compounds characteristic of ginger flavour were detected in zingibain-treated meat. Benzaldehyde significantly increased (p < 0.05) only in kiwifruit juice (KJ), fungal 31 protease and Asparagus protease (ASP) treated samples from 1 day to 21 days PM storage. A significant increase (p < 0.05) in 3-methylbutanal was observed in KJ, bacterial and fungal protease treated samples at 21 days PM storage. Treatments with bromelain, papain, ASP, actinidin, and KJ (except KJ 21 days) proteases resulted in flavour profiles closer to that of the control beef sample.