Combined effect of MAP and thyme essential oil on the microbiological,chemical and sensory attributes of organically aquacultured sea bass (Dicentrarchus labrax) fillets

The present study evaluated the combined effect of Modified Atmosphere Packaging (MAP) using two different gas mixtures (40% CO₂/50% N₂/10% O₂; treatment M1, 60% CO₂/30% N₂/10% O₂, treatment M2), and thyme oil (0.2% v/w, T) used as a natural preservative, on the quality and shelf life extension of fresh filleted sea bass, product of organic aquaculture, during refrigerated storage (4± 0.5 °C), for a period of 21 days. Aerobically packaged sea bass fillets (A) were used as control samples. The dominant bacteria in the microflora of sea bass fillets, irrespective of treatment, were the pseudomonads and the H₂S-producing bacteria while lactic acid bacteria were also part of the dominant microflora. Total viable counts for fresh sea bass fillets stored aerobically exceeded 7 log CFU/g after 7 days, while treatments A+T, M1, M2 and M2+T reached the same value on days 9, 10, 12 and 19, respectively. Among the chemical indices determined, TBA values were within the good quality limits (2–4 mg MDA/kg), during the sensory shelf lives of sea bass samples, irrespective of treatment. TVB-N proved to be a suitable index for the spoilage of sea bass fillets stored at 4 °C. Samples A and A+T, M1, M2, M2+T exceeded the proposed upper TVB-N acceptability limit (10 mg N/100 g) on days 6, 8, 9, 13 and 17 of storage respectively. TMA-N values of the samples A, A+T and M1, M2, M2+T exceeded the proposed limit (4 mg N/100 g) on days 6, 9, 9–10, 13 and 19 of storage, respectively, and correlated well with the microbiological data, indicating that along with TVB-N, TMA-N may serve as a useful index for sea bass fillets spoilage. As regards sensory evaluation, the presence of thyme oil proved to improve the sensory quality of sea bass fillets when used in combination with MAP2, providing a shelf life of 17 days as compared to 6 days of the control samples.     

Changes in quality of rainbow trout (Oncorhynchus mykiss) fillets preserved with salt and sugar at low concentrations and stored at 4°C

The effects of dry-curing with low concentrations of salt and sugar on the quality of rainbow trout (Oncorhynchus mykiss) fillets were studied over a 16-day storage period at 4°C. Physicochemical characteristics (total volatile base nitrogen (TVB-N), biogenic amines (BAs), ATP-related compounds and K value), microbial populations (total aerobic counts (TAC), H₂S-producing bacteria, Pseudomonas, Aeromonas, and lactic acid bacteria) and sensory (SA) indicators were analyzed. Fish samples were subjected to the following treatments: untreated (control), dry-cured with 1.3% salt (T1), and dry-cured with 1.3% salt that also contained 0.9% sugar (T2). SA indicated that the sensory quality of the control, T1, and T2 was unacceptable after 8, 12, and 12 days of storage, respectively. Moreover, the cadaverine concentration of treated samples was significantly lower (P < 0.05) than the control after storing for 8 days. T1 and T2 were significantly higher (P < 0.05) than the control in inosine 5-monophosphate (IMP) content from the 2th to 10th day. Cadaverine, putrescine, hypoxanthine, and TAC were correlated significantly (P < 0.01) with SA, and these seemed to be reliable indicators of fish quality. The results indicated that curing treatments extended the shelf life of rainbow trout fillets, which could be exploited by processors.     

The effect of mendi (Chaerophyllum sp.) on ripening of vacuum-packed herby cheese

The composition, biochemical and sensory parameters of control cheese (without herbs) and four herby cheeses at 0.5, 1, 2 and 3% herb levels (mendi, Chaerophyllum sp.) ripened at 4 ± 1°C for 90 days were compared. As herb levels increased from 0.5 to 3%, dry matter and pH value decreased significantly. However, dry matter of all cheeses showed similar changes during ripening. The salt content of samples changed from 3.44 to 5.47% during ripening. There was a tendency toward slightly higher titratable acidity in cheeses with more added herbs. Ripening index, trichloroacetic acid-soluble nitrogen/total nitrogen, phosphotungstic acid-soluble nitrogen/total nitrogen, and lipolysis values of the cheese samples were affected by adding herbs and by ripening time. The most acceptable sensory score was obtained with 1% added herbs.     

丁香精油-壳聚糖复合可食性膜对生肉糜保鲜效果的影响

研究丁香精油-壳聚糖复合可食性膜对生肉糜冷藏期间感官品质和货架期的影响。测定生肉糜样品在（4±1）℃冷藏期间细菌总数、pH值、硫代巴比妥酸反应物值、高铁肌红蛋白含量以及感官品质随时间的变化情况。结果表明：添加丁香精油可提高壳聚糖可食性膜的抗菌和抗氧化活性。包裹丁香精油-壳聚糖复合可食性膜可有效抑制生肉糜菌落总数和高铁肌红蛋白含量的增加;同时还可抑制贮藏过程中的脂肪氧化,对感官品质具有良好的保持作用,在（4±1）℃条件下贮藏期可达10～12 d,明显提高了生肉糜贮藏过程中的品质和货架期。丁香精油-壳聚糖复合膜可作为可食性包装膜延长生肉糜冷藏期间的货架期。     

A new technology for fish preservation by combined treatment with electrolyzed NaCl solutions and essential oil compounds

This study was undertaken to establish a new technology, using pre-treatment with electrolyzed NaCl solutions and essential oil compounds, to extend the shelf-life of carp fillets. Samples of skinless carp fillets were treated with 100-fold (by weight) of electrolyzed NaCl solutions [cathodic solution, EW(−) and/or anodic solution, EW(+)] and 1% oil (0.5% carvacrol + 0.5% thymol) [1%(C + T)]. Then chemical [pH, volatile basic nitrogen, peroxide value, and thiobarbituric acid], microbiological (total viable count) and sensory analyses were used to evaluate the preservative effect of this new technology during storage at 5 and 25 °C. Our results from the chemical assays indicated that EW(−), followed by EW(+) and subsequently 1%(C + T) [EW(−)/EW(+)/1%(C + T)], significantly suppressed the lipid oxidation compared with other treatments. Data from sensory evaluation and microbiological assay showed that treatment with EW(−)/EW(+)/1%(C + T) extended the shelf-life of carp fillets to 16 and 1.3 days compared with 4 and 0.3 days for the control samples during storage at 5 and 25 °C, respectively.     

Shelf-life extension and quality attributes of the whey cheese “Myzithra Kalathaki” using modified atmosphere packaging

The present work evaluated the effect of modified atmosphere packaging (MAP) on quality characteristics and shelf-life extension of the whey cheese “Myzithra Kalathaki” using microbiological, chemical and sensory analyses. Myzithra cheese was packaged in four different atmospheres: vacuum, 20% CO₂/80% N₂ (M₁), 40% CO₂/60% N₂ (M₂) and 60% CO₂/40% N₂ (M₃); identical cheese samples were packaged in air, taken as controls. All cheese samples were kept under refrigeration (4±0.5 °C) for 45 days. Of the four atmospheres, the M₂ and M₃ gas mixtures were the most effective for inhibiting growth of aerobic microflora and psychrotrophs in cheese samples until days 40 and 33 of refrigerated storage, respectively. Lactic acid bacteria (LAB) were part of the cheese microflora becoming dominant toward the end of the storage period regardless of packaging conditions. Enterobacteriaeceae were also part of the cheese microflora being effectively inhibited after day 35 of storage. Molds and yeasts were also totally inhibited by MAP (M₂ and M₃) gas mixtures throughout the entire storage period. Of the chemical quality indices determined, lipid oxidation varied below 0.005 absorbance at 532 nm for all treatments, except control samples for which absorbance values of 0.02 were recorded after 35 days of storage. Lipolysis did not vary significantly with type of packaging treatment while proteolysis values showed and increasing trend up to day 25 of storage and then decreased toward the end of the storage period. Sensory evaluation (odour and taste) showed that Myzithra cheese packaged under MAP (M₂ and M₃) retained good sensory characteristics for 30 days of storage while control samples were sensorily unacceptable after 10-12 days of storage.     

Shelf-life of a Greek whey cheese under modified atmosphere packaging

“Anthotryros” cheese was packaged under vacuum (VP) or modified atmosphere (MAP) and stored at 4 or 12 °C. MAP mixtures were 30%/70% CO₂/N₂ (M1) or 70%/30% CO₂/N₂ (M2), while VP was taken as the control sample. Microbiological results showed that M1 and M2 delayed microbial growth compared with VP samples. Of the two modified atmospheres, gas mixture M1 was the most effective for inhibition of growth of mesophilic bacteria. Based primarily on sensory evaluation, the use of both MAP conditions extended the shelf-life of fresh Anthotyros cheese stored at 4 °C by ca. 10 days (M1) or 20 days (M2) compared with VP, and by ca. 2 days (M1) and 4 days (M2) at 12 °C, with cheese maintaining good sensory characteristics.     

COMPARATIVE STUDY OF SHELF-LIFE OF FRANKFURTERS CONTAINING PLANT PROTEIN ADDITIVES1

Soy flour (SF), soy concentrate (SC), soy isolate (SI) and corn germ protein flour (CGPF) were incorporated in frankfurters. The sensory analysis, chemical, and microbiological tests were conducted to investigate the effect of plant proteins on stability during vacuum-packaged storage. No significant difference in meaty aroma was found between all samples after 45 days storage. Atypical flavor and aroma of all samples, including the all-meat control increased (P < 0.05) after 45 days storage. A tendency was found of increase in atypical aroma and flavor with increase in total volatile nitrogen values and total psychrophiles during storage. Salty flavor increased with storage time in experimental samples, but juiciness decreased. Samples containing SF and SC had higher total volatile nitrogen than SI and CGPF containing samples at 2, 30 and 45 days of storage. No significant differences were found in TBA values between tested samples, except higher TBA values for SI containing samples. There was no significant difference among samples in total psychrophilic counts.     

Synergistic inhibition of Listeria monocytogenes on cold-smoked rainbow trout by nisin and sodium lactate

The inhibition of Listeria monocytogenes and mesophilic aerobic bacteria in cold-smoked rainbow trout by nisin, sodium lactate or their combination was studied. Nisin (4000-6000 IU/ml), sodium lactate (60%) or their combination (1:1) were injected into rainbow trout at an industrial scale before the smoking process, or injected into the finished smoked product. Both types of fish samples were smoked, sliced and vacuum-packed according to normal practice in the plant. Packages were opened and L. monocytogenes was inoculated (10(3)-10(4) log colony forming units (cfu)/g) onto the fish samples, which were then vacuum packed again. Samples were stored at 8 degrees C for 17 days or at 3 degrees C for 29 days. Listeria and mesophilic aerobic bacteria counts were measured once a week. The effects of treatments on sensory characteristics and storage stability were also analyzed. Both nisin and lactate inhibited the growth of L. monocytogenes in smoked fish, but the combination of the two compounds was even more effective. The combination of nisin and sodium lactate injected into smoked fish decreased the count of L. monocytogenes from 3.26 to 1.8 log cfu/g over 16 days of storage at 8 degrees C. The level of L. monocytogenes remained almost constant (4.66-4.92 log cfu/g) for 29 days at 3 degrees C in the samples injected before smoking and which contained both nisin and sodium lactate. The treatments did not affect the sensory characteristics of cold-smoked rainbow trout. Based on a triangle test, the sensory quality of all test samples remained unchanged for 23 days of storage at 3 degrees C, whereas the control fish prepared without additives or additional salt remained unchanged only for 16 days.     

Quality of monosex tilapia under ice storage: Gutting effects on the formation of biogenic amines,biochemical, and microbiological characteristics

Effects of gutting on biogenic amine (putrescine, cadaverine, histamine, agmatine, tyramine, spermidine, and spermine) formation, biochemical (pH, TVBN, K value), microbial (APC, H₂S producing, Coliform bacteria), and sensory quality of farmed monosex tilapia (Oreochromis niloticus) was studied during ice stored at 4 ± 2ºC. Spermine and spermidine levels were high with cadaverine reached 4.66 ppm in gutted sample. The other amines were detected at relatively low level. K value of both samples crossed 60% on 15th and 18th day, respectively. The total phenolic content exceeded 7 log cfu/g after sensory rejection. The shelf life of whole and gutted samples was estimated to be 24 and 21 days, respectively.     

Effect of chitosan–Jicama starch coating on changes in qualities of fresh Nile tilapia (Oreochromis niloticus) fillets during ice storage

The effect of chitosan (0.5%)/Jicama starch (0%–4%)‐based edible coating on the quality of Nile tilapia (Oreochromis niloticus) fillets was evaluated over ice storage time. All samples were periodically analysed for pH value, thiobarbituric acid (TBA), total volatile basic nitrogen (TVB‐N), electrical conductivity (EC), total viable counts (TVC), total psychrotrophic counts (TPC), drip loss, colour, hardness and sensory characteristics. Results demonstrated that the quality of Nile tilapia fillets was preserved by the film containing chitosan and/or Jicama starch. Compared with chitosan coating alone (0.5% chitosan/0.25% glycerol) (P < 0.05), T3 (0.5% chitosan/1% Jicama starch/0.25% glycerol) had a better effect on the drip loss, TBA, TVC, TPC, hardness and sensory characteristics of the samples, thus indicating that low Jicama starch concentration (1%) enriched the coating ability of chitosan in extending the shelf life of Nile tilapia fillets.     

Edible Coatings to Inhibit Lipid Migration in a Confectionery Product

Coatings containing hydrocolloids and sweetners were tested for lipid barrier and sensory properties, adhesion to chocolate, viscosity, and a_w. A coating containing high methoxyl pectin, acacia gum, high fructose corn syrup, dextrose, fructose, and sucrose was most effective. Coatings (0.5 mm thick, a_w 0.5) showed no detectable oil migration after 47 days at 30 ± l°C, compared to 11.5 mg/cm² trilinolein equivalents migration in 1 day at 21 ± 2°C. Coatings (0.5 mm thick) were applied between chocolate and peanut butter and tested for sensory characteristics. Except for the color of the coating, no significant difference occurred in overall preference compared to control (no coating) samples.     

Effect of gelatin coating incorporated with cinnamon oil on the quality of fresh rainbow trout in cold storage

Cinnamon essential oil was used in gelatin coatings to maintain the quality of refrigerated rainbow trout fillets over a period of 20 days. Fish fillets were coated with a solution of 4% gelatin incorporated with cinnamon essential oil and then stored in refrigerator (4 ± 1 °C). Coating’s preservative effect was assessed periodically (every 5 days) by microbial analyses (aerobic plate count and psychrotrophic count), chemical determinations (total volatile basic nitrogen, thiobarbituric acid, free fatty acid) and sensory characteristics. When gelatin coating with cinnamon applied to the preservation of trout fillets, a reduction in the growth of total bacteria was observe after 15 days of storage. Fish fillets with gelatin coating containing 1%, 1.5% and 2% v/v cinnamon oil produced significantly lower (P < 0.05) total volatile basic nitrogen then gelatin‐coated fillets and control until 15 days of storage period (35, 22.86, 30.33, 57.76 and 53.26 mg per 100 g of fillet, respectively). The obtained results indicate that gelatin in the form of coating enriched with cinnamon oil is suitable for the preservation of rainbow trout fresh fillets and to efficiently maintain the quality attributes to an acceptable level during storage.     

Combined effects of salting,oregano oil and vacuum-packaging on the shelf-life of refrigerated trout fillets

The present study evaluated the effect of salt, oregano essential oil (EO) and packaging on fresh rainbow trout fillets during storage at 4 °C. Treatments included the following: A1 (control samples, unsalted: air packaged), A2 (salted: air packaged), VP1 (salted, vacuum packaged), VP2 (salted, vacuum packaged with added oregano EO 0.2% v/wt), and VP3 salted, vacuum packaged with added oregano EO 0.4% v/wt). Lactic acid bacteria (LAB) (to a greater extent), followed by H₂S-producing bacteria (including Shewanella putrefaciens), Pseudomonas spp. and Enterobacteriaceae reached higher populations in A1, A2 (as compared to VP1, VP2 and VP3) trout samples. Treatments VP1, VP2 and VP3 produced significantly lower (P < 0.05) total volatile basic nitrogen (TVBN) and trimethylamine nitrogen (TMAN) values as compared to the A1 and A2 samples after day 6 and until end of storage period. Changes in thiobarbituric acid values (TBA) values for A1, A2, VP1, VP2 and VP3 samples were variable, indicative of no specific trend in trout samples, irrespective of packaging in the absence and/or presence of salt and oregano EO. As determined by sensory analysis (overall acceptability attribute) the observed shelf-life of trout fillets was longest for VP2 (16–17 days) followed by VP1 (14 days), A2 (8 days) and control (A1) samples (5 days). The presence of salt and oregano oil (0.2%) in cooked VP1 trout samples produced a distinct but sensorially acceptable pleasant odor, well received by the panellists, in contrast to the combined effect of salt and oregano oil at the higher concentrations (0.4% v/wt) used. Addition of salt (treatment VP1) extended the product's shelf-life by 9 days, whereas the combination of salt, oregano EO (0.2% v/wt) under VP conditions (treatment VP2) resulted in a significant shelf-life extension of trout fillets (11–12 days) according to sensory data, as compared to the control sample, kept under aerobic conditions.     

The storage stability and textural, physico-chemical and sensory quality of low-fat ground pork patties with Carrageenan as fat replacer

Low‐fat ground pork patties (<10% total fat) made with carrageenan added at either 0.25, 0.50 or 0.75% final concentration were processed and the compositional and sensory characteristics compared with control patties which contained 20% fat. The moisture content of raw and cooked low‐fat patties was significantly (P < 0.05) higher than control patties because of greater amounts of water added during formulation. Cooking yield, fat and moisture retention also improved significantly (P < 0.05) in low‐fat patties that had carrageenan incorporated when compared to a control product. The dimensions of the low‐fat patties were maintained better than those of the control product during cooking. The sensory attributes of low‐fat patties with 0.5% carrageenan were similar to those of the high‐fat control. The lipid profile revealed as much as a 47.7 or 44.1% decrease in total lipids and cholesterol content respectively, compared with the controls. The calorie content was reduced by 31.1% in low‐fat cooked patties compared with the controls. The texture profile of low‐fat patties that had been made with 0.5% carrageenan were similar to control patties with only a slight increase in hardness and gumminess in the low‐fat product. The low‐fat ground pork patties made in the present study remained stable without any appreciable loss of physico‐chemical, microbiological and organoleptic quality during refrigerated storage (4 ± 1 °C) for 21 and 35 days in aerobic and vacuum packaging respectively.     

Quality changes of sea bass slices wrapped with gelatin film incorporated with lemongrass essential oil

Microbiological, chemical and physical changes of sea bass slices wrapped with gelatin film incorporated with 25% (w/w) lemongrass essential oil (LEO) during storage of 12 days at 4 °C were investigated. Sea bass slices wrapped with LEO film had the retarded growth of lactic acid bacteria (LAB), psychrophilic bacteria and spoilage microorganisms including H?S-producing bacteria and Enterobacteriaceae throughout storage of 12 days in comparison with the control and those wrapped with gelatin film without LEO (G film) (P<0.05). Lowered changes of colour, K value, total volatile base nitrogen (TVB) and TBARS value were also found in LEO film wrapped samples, compared with those wrapped with G film and control, respectively. Therefore, the incorporation of LEO into gelatin film could enhance the antimicrobial and antioxidative properties of the film, thereby maintaining the qualities and extending the shelf-life of the sea bass slices stored at refrigerated temperature.     

Gelatin/pectin-based film incorporated with essential oils: Functional characteristics and shelf life extension of tilapia fillets under refrigeration

Fish gelatin-pectin (Gel_Ext/Pec) composite films incorporated with Mentha pulegium essential oil (MEO) and Lavandula angustifolia essential oil (LEO) at two concentrations (0.5% and 1.5%) were developed and their physicochemical, mechanical, and antimicrobial properties were determined. Gel_Ext/Pec-based film incorporated with 1.5% MEO (Gel_Ext/Pec + 1.5% MEO) showed the highest antimicrobial activity against all bacterial strains tested. Incorporation of essential oils decreased significantly the tensile strength of all the films investigated. The film showing the best functional and antimicrobial properties (Gel_ext/Pec + 1.5% MEO) was used to prolong the shelf life of tilapia fillets under refrigeration. Control (unwrapped) and wrapped fillets were analyzed every 3 days in terms of microbiological (total viable count (TVC), psychrotrophic bacteria count (PC), lactic acid bacteria (LAB) and Enterobacteriaceae (ENT), and physicochemical parameters (total volatile base nitrogen [TVB-N] and pH). Gel_ext/Pec + 1.5% MEO antimicrobial film retarded significantly (p < .05) the growth of TVC, LAB, PC, and ENT, throughout 12 days of storage compared with the control. Gel_ext/Pec + 1.5% MEO could be considered as an effective packaging to maintain the quality and extend the shelf life of tilapia fillets under refrigeration.     

白萝卜粉作为亚硝酸盐来源制备猪肉发酵干香肠

评价用白萝卜粉代替亚硝酸盐制备猪肉发酵干香肠的可行性。采用萨科VBM-60复合菌株作发酵剂，制备4组香肠：NC组（不添加硝酸盐或亚硝酸盐的阴性对照组）、PC组（添加150 mg/kg亚硝酸钠的阳性对照组）、R0.5组（添加0.5%白萝卜粉组）、R1组（添加1%白萝卜粉组）。研究加工和贮藏过程中白萝卜粉代替亚硝酸盐对猪肉发酵干香肠理化性质、微生物性质及感官性质的影响。结果表明：与添加150 mg/kg亚硝酸钠的对照组相比，添加0.5%白萝卜粉的香肠具有较高硫代巴比妥酸反应物值和较好外观，以及较低的pH值、红度值、硬度和咀嚼性，而水分含量、挥发性盐基氮值、亮度值、弹性、内聚性、菌落总数、组织状态、色泽和风味总体上差异不显著。在贮藏过程中，R0.5组香肠具有较高的亚硝酸盐含量和较低的乳酸菌数。R0.5组香肠在加工和贮藏结束时的亚硝酸盐含量分别为13.03 mg/kg和16.48 mg/kg，均符合国家规定的限定标准。结果表明，添加0.5%的白萝卜粉可在一定程度上作为天然亚硝酸盐来源，用于生产猪肉发酵干香肠。     

The effect of filleting and ice application on the quality and safety of Atlantic bonito (Sarda sarda) at refrigerated storage

Filleting effect of refrigerated bonito with and without ice on the quality changes and food safety was investigated. Significant variations occurred (P < 0.05) in sensory, chemical and microbiological values amongst groups. The best sensory results were found for filleted bonito with ice (FBRI) with a shelf‐life of 13 days. While sensory values decreased significantly during storage, opposite situation occurred for both chemical and microbiological results (P < 0.05). The lowest total volatile basic nitrogen value was also observed with FBRI and was within the acceptable levels for 15 days as 17.86 mg 100 g^?1. All samples contained acceptable trimethylamine levels for 15 days despite unacceptable sensory values after certain days. Although filleting seemed to increase the lipid oxidation, ice application resulted in lowering thiobarbituric acid content. Histamine results closely supported sensory values in terms of legally permitted levels usually by set FDA. While WBR contained histamine value over EU permitted level as 113.78 ppm on the 7th day, the value for FBRI was 56.13 ppm on the 15th day. Histamine‐forming bacteria counts supported histamine formation in most groups, while total bacteria counts were in agreement with sensory results. This study suggests that using ice and filleting can improve shelf‐life of bonito stored at refrigerated temperatures in terms of food quality and safety.