Oxidative stability of lipid components of mullet (Mugil cephalus) roe and its product “bottarga”

The lipid composition and oxidative stability of mullet (Mugilcephalus) raw roes and cured products (bottarga) from two different fishing areas have been studied and compared to find lipid modifications due to manufacturing procedures. Moreover, n-3 PUFA oxidation in raw roes and cured products was monitored during storage at −20 °C, and in grated sample of bottarga at room temperature. Oxidative degradation of n-3 PUFA was evaluated by conjugated dienes fatty acids hydroperoxides determination. The treatments on mullet roe did not affect the lipid level (fatty alcohols and acids, cholesterol) and the amount of hydroperoxides. No significant difference is observed between n-3 PUFA levels during processing and at different storage conditions. The order of oxidative stability, as calculated by the hydroperoxides determination was: grated bottarga < whole bottarga < raw roe.     

Stability of potassium iodide and omega-3 fatty acids in fortified freshwater fish emulsion sausage

Oxidative stability of emulsion sausages prepared from African walking catfish (AF: Clarias gariepinus) and rohu (RH: Labeo rohita) fortified with three levels of the refined tuna oil (2%, 6%, and 10%) with 150 μg KI/100 g sample and without KI was investigated. The control was prepared using 20% soybean oil and without KI. Samples were vacuum-packed and stored at 4 °C. Iodine content decreased approximately 14% after cooking and remained constant throughout storage. Sausages fortified with tuna oil showed higher level of n-3 (eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)), but lower level of n-6 fatty acids (P<0.05) than the control. The ratio of n-6 to n-3 fatty acids of all samples decreased with an increase of tuna oil addition and was stable throughout 4 weeks of storage. Degradation of linoleic (LA) and linolenic acid (LNA) mainly occurred in the samples added 2% tuna oil whereas samples fortified with higher tuna oil (6-10%) exhibited higher loss of EPA and DHA. Hydroperoxide (HPV) and thiobarbituric reactive substances (TBARS) values were increased as addition level of tuna oil increased. Textural properties were not affected during storage at 4 °C for up to 4 weeks (P<0.05). Based on lipid stability results, 2% fortification of the refined tuna oil was recommended for emulsion sausage prepared from both species. Addition of 150 μg KI/100 g had no effect on lipid oxidation of fish sausages (P<0.05).     

Efficacy of neutral electrolyzed water for sanitization of cutting boards used in the preparation of foods

The effectiveness of neutral electrolyzed water (NEW) to sanitize cutting boards used for food preparation was investigated. Cutting boards made of hardwood and bamboo were inoculated with Escherichia coli K12 and Listeria innocua, dried for 1 h, washed, rinsed and sanitized with NEW, sodium hypochlorite (NaClO) solution, or tap water (control). After each washing protocol, surviving bacterial populations were determined. Results showed that both NEW and NaClO sanitizing solutions produced similar levels of bacterial reductions. In manual washing, the population reductions by NEW and NaClO were 3.4 and 3.6 log₁₀ CFU/100 cm² for E. coli, and 4.1 and 3.9 log₁₀ CFU/100 cm² for L. innocua, respectively. In the automatic washing, the reductions by NEW and NaClO were 4.0 and 4.0 log₁₀ CFU/100 cm² for E. coli, and 4.2 and 3.6 log₁₀ CFU/100 cm² for L. innocua, respectively. No significant differences (P > 0.05) were observed in surviving bacteria counts when comparing board material types.     

Differential effects of n-3 and n-6 fatty acids on prostaglandin F2alpha production by bovine endometrial cells

Recent studies have implicated n-3 polyunsaturated fatty acids in the reduction of eicosanoid production in the bovine uterus. The objective of this study was to determine whether the effect of eicosapentaenoic acid (EPA; C_20:5, n-3) on PGF_2α production by bovine endometrial (BEND) cells is influenced by the quantity of linoleic acid (C_18:2, n-6) in the incubation medium. Confluent BEND cells were incubated in the absence (control) or presence of 100 μMof EPA for 24 h. After incubation, cells were rinsed and then stimulated with phorbol 12,13-dibutyrate (PDBu; 100 ng/mL) for 6 h. Additional sets of culture dishes were treated with a combination of EPA and increasing n-6/n-3 fatty acid ratios for 24 h and then challenged with PDBu for 6 h. The PDBu stimulated PGF_2α secretion and upregulated steady-state concentrations of prostaglandin endoperoxide synthase-2 and peroxisome proliferator-activated receptor delta mRNA within 6 h. Preincubation of BEND cells with EPA for 24 h decreased PGF_2α response to phorbol ester, but had no detectable effects on prostaglandin endoperoxide synthase-2 or peroxisome proliferator-activated receptor delta mRNA abundance in PDBu-stimulated BEND cells. The inhibitory effect of EPA on PGF_2α production was reverted in BEND cells treated with an increasing n-6-to-n-3 fatty acid ratio. Findings indicate that the net inhibition of endometrial PGF_2α bioynthesis by n-3 fatty acids may vary depending on the ratio of n-6 to n-3 fatty acids in the uterus.     

Effects of fatty acid oxidation products (green odor) on rumen bacterial populations and lipid metabolism in vitro

This study investigated the effects of green odor fatty acid oxidation products (FAOP) from cut grass on lipid metabolism and microbial ecology using in vitro incubations of rumen microorganisms. These compounds have antimicrobial roles in plant defense, and we hypothesized that they may influence rumen lipid metabolism. Further, they may partially explain the higher levels of conjugated linoleic acid cis-9, trans-11 in milk from cows grazing pasture. The first of 2 batch culture experiments screened 6 FAOP (1 hydroperoxide, 3 aldehydes, 1 ketone, and 1 alcohol) for effects on lipid profile, and in particular C₁₈ polyunsaturated fatty acid biohydrogenation. Experiment 2 used the most potent FAOP to determine effects of varying concentrations and identify relationships with effects on microbial ecology. Batch cultures contained anaerobic buffer, rumen liquor, and FAOP to a final concentration of 100 μM for experiment 1. Triplicates for each compound and controls (water addition) were incubated at 39°C for 6 h. The hydroperoxide (1,2-dimethylethyl hydroperoxide, 1,2-DMEH) and the long chain aldehyde (trans-2 decenal) had the largest effects on lipid metabolism with significant increases in C_18:0 and C_18:1trans and reductions in C_12:0, C_14:0, C_16:0, C_18:1cis, C_18:2n-6, C_18:3n-3, C_20:0 and total branch and odd chain fatty acids compared with the control. This was associated with significantly higher biohydrogenation of C₁₈ polyunsaturated fatty acid. In experiment 2, 1,2-DMEH was incubated at 50, 100, and 200 μM for 2, 6, and 24 h. Increasing 1,2-DMEH concentration resulted in a significant linear increase in C_18:1trans-10, trans-11, conjugated linoleic acid, and C_18:0 and a linear decrease in C_18:2n-6 and C_18:3n-3, although the scale of this response declined with time. Microbial profiling techniques showed that 1,2-DMEH at concentrations of 100 and 200 μM changed the microbial community from as early as 2 h after addition, though microbial biomass remained similar. These preliminary studies have shown that FAOP can alter fatty acid biohydrogenation in the rumen. This change was associated with changes in the microbial population that were detected through DNA and branched- and odd-chain fatty acid profiling approaches.     

Preparation of eicosapentaenoic acid concentrates from sardine oil by Bacillus circulans lipase

An extracellular lipase derived from Bacillus circulans, isolated from marine macroalga, Turbinaraia conoides, was used to prepare n-3 polyunsaturated fatty acid (PUFA) concentrates from sardine oil triglycerides. The enzyme was purified 132-fold with specific activity of 386 LU/mg. The purified lipase was able to enrich sardine oil with 37.7 ± 1.98% 20:5n-3 and 5.11 ± 0.14% 18:3n-3 in the triglyceride fraction after 3 h of hydrolysis. Lower hydrophobic constants of n-3 fatty acids (18:3n-3_logP = 5.65; 20:5n-3_logP = 5.85, respectively) than n-6 (20:4n-6_logP = 6.16) resulted in higher hydrolytic resistance of the former toward lipase, leading to their enrichment in the triglyceride fraction. Lipase-catalysed hydrolysis of sardine oil for 3 h, followed by urea complexation, provided free fatty acids containing 51.3 ± 4.65% 20:5n-3. The purified methyl ester of 20:5n-3 (68.29 ± 2.15%) from the urea concentrate was attained by chromatography on argentated neutral alumina.     

Organic acids,antioxidant capacity,phenolic content and lipid characterisation of Georgia-grown underutilized fruit crops

Four underutilized Georgia-grown fruit crops, namely loquat (Eriobotrya japonica), mayhaw (Crataegus sp.), fig (Ficus carica), and pawpaw (Asimina triloba), and their leaves were analysed for total polyphenols by Folin–Ciocalteau method, and antioxidant capacity by ferric-reducing antioxidant power (FRAP) and Trolox-equivalent antioxidant capacity (TEAC) assays. Organic acids and phenolic compounds were identified by RP-HPLC. For lipid profile, fruits were separated into two fractions – seed and fruit (i.e., without seed); lipid was extracted using the Folch method and analysed for fatty acids, phytosterols, tocopherols, and phospholipids. The major organic acid identified in all samples was malic acid (177–1918 mg/100 g FW). The predominant phenolic acids in all the fruits were gallic (1.5–6.4 mg/100 g FW) and ellagic (0.2–33.8 mg/100 g FW), and the most abundant flavonoid was catechin (12.2–37.8 mg/100 g FW). Total lipid content varied from 0.1% in mayhaw fruit to 21.5% in pawpaw seed. Linoleic acid was the predominant fatty acid in all of the samples (28.2–55.7%).     

Nutritional and commercial quality of the striped venus clam, Chamelea gallina, from the Adriatic sea

Nutritional quality parameters (proximate and mineral composition, contents of glycogen, fatty acids, cholesterol, plant sterols, fat-soluble vitamins, carotenes) and ecophysiological and commercial quality indicators (Condition Index, percent content of meat and intervalvar fluid) of the striped venus clam, Chamelea gallina, from the central Adriatic coast of Italy were studied at seasonal intervals over a 1-year period. Contents of protein (8.55–10.7 g/100 g), total lipid (0.73–1.59 g/100 g), glycogen (2.25–4.96 g/100 g) and non-protein nitrogen (0.54–0.78 g/100 g) varied significantly during the year, reaching the highest values in winter, in coincidence with a peak of Condition Index. Gas chromatography of total lipids showed high percentages of n − 3 polyunsaturated fatty acids (33.7–41.9% of total fatty acids), in particular eicosapentaenoic (8.16–20.0% of total fatty acids) and docosahexaenoic acids (12.5–20.3% of total fatty acids) and low levels of total n − 6 polyunsaturated fatty acids (3.61–7.87% of total fatty acids). HPLC analysis of the unsaponifiable lipids showed low levels of cholesterol, the dominant sterol (28.3–34.2 mg/ 100 g), and variable amounts of plant sterols (stigmasterol + campesterol, β-sitosterol, fucosterol + brassicasterol), α-tocopherol and carotenes.     

Spoilage characteristics of Brochothrix thermosphacta and campestris in chilled vacuum packaged lamb,and their detection and identification by real time PCR

The spoilage potential of Brochothrix campestris and Brochothrix thermosphacta was investigated in vacuum-packed lamb. Striploins (n = 338) were inoculated and stored for twelve weeks at temperatures − 1.5, 0, 2 and 7 °C. Growth around 5–6 log₁₀ CFU/cm² was recorded after six weeks at 0, 2 and 7 °C, and ~ 3 log₁₀ CFU/cm² after nine weeks at − 1.5 °C. B. campestris was shown to cause spoilage by nine weeks at temperatures above 0 °C by the presence of green drip and unacceptable odours. Molecular based assays for the detection and differentiation of B. thermosphacta and B. campestris were developed and validated. A TaqMan assay was designed to target a unique single-nucleotide polymorphism in the Brochothrix 16 s rRNA gene with a sensitivity of < 7 CFU per reaction. Secondly a specific PCR was designed for B. campestris targeting the structural genes, brcA and brcB. These testing regimes offer a rapid and cost effective method for the detection and screening of Brochothrix species in meat products and processing environments.     

Chemical compositions of the roes from skipjack,tongol and bonito

Chemical compositions of roes from three tuna species including skipjack (Katsuwonous pelamis) (SJK), tongol (Thunnus tonggol) (TGL) and bonito (Euthynnus affinis) (BNO) were determined. Tuna roes contained 72.17–73.03% moisture, 18.16–20.15% protein, 3.29–5.68% lipid and 1.79–2.10% ash. Non-defatted and defatted roes from all species contained protein with a molecular weight of 97 kDa as the major component. Glutamic acid and glutamine were the most abundant amino acids (12.18–12.65 g/100 g protein), while K, Na and P were the major elements in defatted-tuna roes. Crude lipids from tuna roes contained phospholipids as the major component (51.22–54.90% of total lipids) with high content of docosahexaenoic acid (C22:6 n-3) (20.53–26.19% of total lipids). Cholesterol contents of crude lipids from the roes of SJK, TGL and BNO were 172, 122 and 94 mg/100 g lipids, respectively. Therefore, tuna roe could be a promising source of valuable nutrients for human food and animal feeds.     

Efficacy of bacteriophage LISTEXP100 combined with chemical antimicrobials in reducing Listeria monocytogenes in cooked turkey and roast beef

The aim of this study was to verify the effectiveness of the commercially available anti-Listeria phage preparation LISTEX^™P100 in reducing Listeria monocytogenes on ready-to-eat (RTE) roast beef and cooked turkey in the presence or absence of the chemical antimicrobials potassium lactate (PL) and sodium diacetate (SD). Sliced RTE meat cores at 4 and 10 °C were inoculated with cold-adapted L. monocytogenes to result in a surface contamination level of 10³ CFU/cm². LISTEX^TMP100 was applied at 10⁷ PFU/cm² and samples taken at regular time intervals during the RTE product's shelf life to enumerate viable L. monocytogenes. LISTEX^™P100 was effective during incubation at 4 °C with initial reductions of L. monocytogenes of 2.1 log₁₀ CFU/cm² and 1.7 log₁₀ CFU/cm², respectively, for cooked turkey and roast beef without chemical antimicrobials (there was no significant difference to the initial L. monocytogenes reductions in the presence of LISTEX^TMP100 for cooked turkey containing PL and roast beef containing SD-PL). In the samples containing no chemical antimicrobials, the presence of phage resulted in lower L. monocytogenes numbers, relative to the untreated control, of about 2 log CFU/cm² over a 28-day storage period at 4 °C. An initial L. monocytogenes cell reduction of 1.5 log₁₀ CFU/cm² and 1.7 log₁₀ CFU/cm², respectively, for cooked turkey and roast beef containing no chemical antimicrobials was achieved by the phage at 10 °C (abusive temperature). At this temperature, the L. monocytogenes cell numbers of samples treated with LISTEX™ P100 remained below those of the untreated control only during the first 14 days of the experiment for roast beef samples with and without antimicrobials. On day 28, the L. monocytogenes numbers on samples containing chemical antimicrobials and treated with LISTEX^TMP100 stored at 4 and 10 °C were 4.5 log₁₀ CFU/cm² and 7.5 log₁₀ CFU/cm², respectively, for cooked turkey, and 1.2 log₁₀ CFU/cm² and 7.2 log₁₀ CFU/cm², respectively, for roast beef. In both cooked turkey samples with and without chemical antimicrobials stored at 10 °C, the phage-treated samples had significantly lower numbers of L. monocytogenes when compared to the untreated controls throughout the 28-day storage period (P < 0.0001). For roast beef and cooked turkey containing chemical antimicrobials treated with LISTEX^TMP100 and stored at 4 °C, no more than a 2 log CFU/cm² increase of L. monocytogenes was observed throughout the stated shelf life of the product. This study shows that LISTEX^™P100 causes an initial reduction of L. monocytogenes numbers and can serve as an additional hurdle to enhance the safety of RTE meats when used in combination with chemical antimicrobials.     

In vitro inactivation of Escherichia coli, Staphylococcus aureus and Salmonella spp. using slightly acidic electrolyzed water

In the current study, the effectiveness of slightly acidic electrolyzed water (SAEW) on an in vitro inactivation of Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Salmonella spp. was evaluated and compared with other sanitizers. SAEW (pH 5.6, 23 mg/l available chlorine concentration; ACC; and 940 mV oxidation reduction potential; ORP) was generated by electrolysis of dilute solution of HCl (2%) in a chamber of a non-membrane electrolytic cell. One milliliter of bacteria suspension (ca. 10–11 log₁₀CFU/ml) was mixed with 9 ml of SAEW, strong acidic electrolyzed water (StAEW; ca. 50 mg/l ACC), sodium hypochlorite solution (NaOCl; ca.120 mg/l ACC) and distilled water (DW) as control and treated for 60 s. SAEW effectively reduced the population of E. coli, S. aureus and Salmonella spp. by 5.1, 4.8, and 5.2 log₁₀CFU/ml. Although, ACC of SAEW was more than 5 times lower than that of NaOCl solution, they showed no significant bactericidal difference (p > 0.05). However, the bactericidal effect of StAEW was significantly higher (p < 0.05) than SAEW and NaOCl solution in all cases. When tested with each individual test solution, E. coli, S. aureus and Salmonella spp. reductions were not significantly different (p > 0.05). These findings indicate that SAEW with low available chlorine concentration can equally inactivate E. coli, S. aureus and Salmonella spp. as NaOCl solution and therefore SAEW shows a high potential of application in agriculture and food industry as an environmentally friendly disinfection agent.     

Composition and antioxidative activities of supercritical CO2-extracted oils from seeds and soft parts of northern berries

The present study investigated the composition and the antioxidative activities of oils from the seeds and the soft parts of a range of northern berries extracted by supercritical CO₂. The seed oils of the species of Rubus, Vaccinium, Empetrum, Fragaria and Hippophaë were rich in linoleic (18:2n-6, 34-55% of total fatty acids) and ??-linolenic (18:3n-3, 29-45% of total) acids with n-6:n-3 ratios of 1:1-1:2. The seed oils of the species Ribes contained, in addition to linoleic and ??-linolenic acids, ??-linolenic (18:3n-6) and stearidonic (18:3n-4) acids. In seed oils from European rowanberry (Sorbus aucuparia L.) and snowball berry (Viburnum opulus L.), linoleic and oleic (18:1n-9) acids together exceeded 90% of the total fatty acids. The sea buckthorn (SB) pulp oil had palmitoleic (16:1n-7), palmitic (16:0) and oleic acids as the major fatty acids. The SB pulp oil and snowball berry seed oil were rich in ??-tocopherol (120 and 110 mg/100 g oil, respectively), whereas raspberry seed oil contained a high level of ??-tocopherol (320 mg/100 g oil). Seed oils of cranberry (180 mg/100 g oil), Arctic cranberry (190 mg/100 g oil) and lingonberry (120 mg/100 g oil) are rich sources of ??-tocotrienol. The berry seed oils and the SB pulp oil showed varying peroxyl radical scavenging efficacies (300-2300 ??mol ??-tocopherol equivalent per 100 g oil) and inhibitory effects on perioxidation of microsomal lipids (250-1200 ??mol trolox equivalent per 100 g oil) in vitro. The peroxyl radical scavenging activity positively correlated with the total content of tocopherols and tocotrienols of the oils (r = 0.875, P = 0.001). The SB seed oil and pulp oil were active in scavenging superoxide anions produced by xanthine-xanthine oxidase system and inhibited Cu²⁺-induced LDL oxidation in vitro. The SB oils also protected purified DNA and rat liver homogenate from UV-induced DNA oxidation in vitro. The current research suggests potential of supercritical CO₂-extracted oils from northern berries as nutraceuticals and ingredients of functional foods.     

New trends in the seafood market. Sutchi catfish (Pangasius hypophthalmus) fillets from Vietnam: Nutritional quality and safety aspects

Sutchi catfish (Pangasius hypophthalmus) produced in the freshwater basins of Vietnam, available on the Italian market as frozen or thawed fillets, were studied for their nutritional quality and safety aspects. Proximate composition, mineral content, fatty acid profile, unsaponifiable components of the lipid fraction and drip loss during thawing at 5 °C were determined on the fillets. Fillets were characterised by high moisture levels (80–85%) and low protein (12.6–15.6%) and lipid (1.1–3.0%) contents. Total lipids were characterised by low cholesterol levels (21–39 mg/100 g), high percentages of saturated fatty acids (41.1–47.8% of total fatty acid) and low percentages of polyunsaturated fatty acids (12.5–18.8% of total fatty acids), which were mainly represented by linoleic acid (44–59% of total polyunsaturated fatty acids). The mineral composition was characterised by a high sodium content (222–594 mg/100 g), probably partially due to the sodium tripolyphosphate (E 451) used to retain moisture. As regards safety aspects, the quality of the samples analysed was good, with low residue levels of mercury, organochlorine pesticides and polychlorinated biphenyls.     

Triglycerides constituted of short and medium chain fatty acids and dicarboxylic acids in Momordica charantia, as well as capric acid,inhibit PGE2 production in RAW264.7 macrophages

This study was aimed to identify compounds in bitter gourd (Momordica charantia) ethyl acetate extract (EAE), which inhibit lipopolysaccharide-induced prostaglandin E₂ (PGE₂) production in RAW264.7 cells. Bitter gourd EAE was partitioned between n-hexane and methanol/H₂O (90/10). The hexane fraction was further separated by repeated silica gel chromatographies, and a reverse phase (RP) C18 chromatography. Fraction RP-10 showed the highest inhibition effect on PGE₂ production (Max inhibition = 96%, IC₅₀ = 2.3 μg/ml) and was identified to be triglycerides constituted of short and medium chain fatty acids by ¹H NMR, IR and H–HCOSY, and dicarboxylic acids by GC/MS. Fatty acids with 3–20 carbons were tested for the inhibitory activity, and capric acid exhibited the highest effect (Max inhibition = 99%, IC₅₀ = 6.5 μM). In conclusion, triglycerides composed of short and medium chain fatty acids and dicarboxylic acids in bitter gourd inhibit PGE₂ production, and capric acid is the most potent inhibitor among the fatty acids.     

Changes of proximate and fatty acid compositions of the dorsal and ventral ordinary muscles of the full-cycle cultured Pacific bluefin tuna Thunnus orientalis with the growth

Using the full-cycle cultured (FC) Pacific bluefin tuna, Thunnus orientalis [body weights: 13.1 ± 4.5 (FC1; April in 2004), 20.2 ± 1.8 (FC2; July in 2004), 28.5 ± 6.3 (FC3; November in 2004), 27.0 ± 3.3 (FC4; February in 2005) and 33.5 ± 4.7 kg (FC5; May in 2005), n = 3, respectively] and wild bluefin tuna [33.3 ± 1.5kg (June in 2005), n = 3], proximate and fatty acid compositions of the cephalal (Ce-) and caudal (Ca-) parts of the dorsal (D) and ventral (V) ordinary muscles (OMs) were investigated. Lipid contents of the Ce-DOM and VOMs of FC1-5 increased with growth. In particular, lipid content of the Ce-DOM (23.0%) and VOMs (55.1%) of FC5 was higher (P < 0.05) than those of wild tuna [D-(2.0%) and VOMs (16.2%)]. However, lipid contents of the Ca-DOM and VOMs of FC1-5 did not change with growth. On the other hand, the fatty acid compositions of the Ce-DOM and VOMs of FC2-5 resembled each other. However, there was no specific tendency of the changes of each fatty acid composition of the Ce-DOM of FC tuna with growth. On the other hand, total monounsaturated fatty acid content (30.1%) of the Ce-DOM of FC5 was higher (P < 0.05) than that (25.5%) of wild tuna. The ratio of n–3: n–6 (9.4%) of the Ce-VOM of FC5 was lower (P < 0.05) than that (14.0%) of wild tuna. However, the fatty acid compositions of the Ce-DOM and VOMs of FC tuna were not reflected by those of feed (whole fish bodies of sesame mackerel).     

Pasteurization of grapefruit juice using a centrifugal ultraviolet light irradiator

Studies are lacking on the nonthermal pasteurization of liquid foods using UV irradiators that centrifugally form very thin films to overcome the problem of limited penetration depth of UV. Grapefruit juice inoculated with Escherichia coli or Saccharomyces cerevisiae was processed at the following conditions: UV dose 4.8–24 mJ/cm²; treatment time 3.2 s, cylinder rotational speed 450–750 rpm, cylinder inclination angle 15–45°, outlet temperature 11 °C, and flow rate 300 ml/min, and was stored for 35 days. Appropriate dilutions of the samples were pour plated with TSA and TSA + 3% NaCl for E. coli and Sabouraud dextrose agar (SDA) and SDA + 5% NaCl for S. cerevisiae. Nonthermal UV processing at 19 mJ/cm², 450 rpm and 15° reduced E. coli in grapefruit juice by 5.1 log₁₀. A dose of 14 mJ/cm² reduced S. cerevisiae by 6.0 log₁₀. Inactivation increased linearly with increasing UV dose. The inactivations at 600 and 750 rpm were similar, and were better than at 450 rpm. The results at 30° and 45° were similar, and were better than at 15°. The occurrence of sublethal injury in either microorganism was not detected. Storing UV processed grapefruit juice at 4 and 10 °C reduced the surviving E. coli to below 1 log₁₀ cfu/ml in 14 days. Processing UV juice reduced the population of S. cerevisiae to less than 1 log₁₀ cfu/ml where it remained for 35 days during refrigerated storage. These results suggest that grapefruit juice may be pasteurized using a nonthermal UV irradiator that centrifugally forms a thin film.     

Application of high pressure processing to reduce verotoxigenic E. coli in two types of dry-fermented sausage

The effect of high pressure processing (HPP) on the survival of verotoxigenic Escherichia coli (VTEC) in two types of Norwegian type dry-fermented sausages was studied. Two different types of recipes for each sausage type were produced. The sausage batter was inoculated with 6.8 log₁₀ CFU/g of VTEC O103:H25. After fermentation, drying and maturation, slices of finished sausages were vacuum packed and subjected to two treatment regimes of HPP. One group was treated at 600 MPa for 10 min and another at three cycles of 600 MPa for 200 s per cycle. A generalized linear model split by recipe type showed that these two HPP treatments on standard recipe sausages reduced E. coli by 2.9 log₁₀ CFU/g and 3.3 log₁₀ CFU/g, respectively. In the recipe with higher levels of dextrose, sodium chloride and sodium nitrite E. coli reduction was 2.7 log₁₀ CFU/g in both treatments. The data show that HPP has a potential to make the sausages safer and also that the effect depends somewhat on recipe.     

Seasonal variation in the fatty acid composition of three Mediterranean fish – sardine (Sardina pilchardus), anchovy (Engraulis encrasicholus) and picarel (Spicara smaris)

The total fat contents and the fatty acid compositions of three common Mediterranean fish, namely sardine (Sardina pilchardus), anchovy (Engraulis encrasicholus) and picarel (Spicara smaris) were determined at bimonthly intervals for a one-year period. The purpose of this work was to study the seasonal variation of the fatty acids in the three fish that are some of the best sources of n − 3 fatty acids. The fat and fatty acid content of the investigated fish species show a significant seasonal dependency. Two of the fish (anchovy and picarel) have the highest fat content during the late winter – spring period. On the other hand, sardine shows the highest fat concentrations during the spring-early summer period. The fish that showed the highest variation in fatty acid composition was the anchovy. The sardine was found to be the best source of n − 3 fatty acids during the one-year period (35.35 g/100 g fatty acids). Finally the picarel had the highest oleic acid content (on average, 13.89/100 g fatty acids).     

A predictive model for assessment of decontamination effects of lactic acid and chitosan used in combination on Vibrio parahaemolyticus in shrimps

Vibrio parahaemolyticus is a major causative agent of human gastroenteritis in seafood products including shrimps. Lactic acid and chitosan are natural antimicrobials for food decontamination in the washing process of seafood. In this research, a 4-factor response surface model based on the Box–Behnken experimental design was developed to evaluate the effects of lactic acid (1%, 2%, and 3%, v/v), chitosan (0.4%, 1%, and 1.6%, w/v), rotational rate (90, 110, and 130 rpm) and washing time (10, 20, and 30 min) on reduction of V. parahaemolyticus inoculated in raw shrimps. These treatments achieved 2.2 to 4.3 log₁₀ CFU/g reduction of V. parahaemolyticus in shrimps. Stepwise stratification led to a simplified model that has a satisfactory performance as evidenced by statistical indices (R² = 0.92; p < 0.0001; RMSE = 0.196) and external validation parameters [bias factor (B_f) = 1.01; accuracy factor (A_f) = 1.05]. The model generated an optimum treatment combination (3% lactic acid, 1.6% chitosan, and rotational rate at 110 rpm) that could achieve greatest bacterial reduction of 4.5 log₁₀ CFU/g. Among the four factors, lactic acid and chitosan were the major contributors for bacterial decontamination. Analysis of variances showed a significant interactive inactivation effect (p < 0.05) from combined use of lactic acid and chitosan. The treatments did not have adverse effects on the quality attributes such as color and pH of the shrimps.