Effect of chitosan coatings enriched with cinnamon oil on the quality of refrigerated rainbow trout

Biogenic amines formation, nucleotide degradation and TVB-N accumulation of vacuum-packed minced sturgeon (Acipenser schrencki) stored at 4 °C and their relation to microbiological attributes

BACKGROUND

Sturgeon (Acipenser schrencki) were filleted, minced, vacuum-packed and stored at 4 °C. Minced sturgeon muscles were analysed for 10 days to determine biochemical [eight biogenic amines, ATP and breakdown products, K value, total volatile basic nitrogen (TVB-N) and pH], microbiological (total viable counts, Enterobacteriaceae, Psychrotrophs, Pseudomonas, Aeromonas, Vibrio, Lactobacillus and Brochothrix thermosphacta) changes and their relationships.

RESULTS

The shelf-life of sturgeon was found to be 3-4 days according to microbiological assessment. At the end of the storage, Psychrotrophs, Enterobacteriaceae and Aeromonas became the dominant bacteria, reaching 7.85, 7.98 and 8.02 log cfu g(-1), respectively. Biogenic amines, hypoxanthine and the K value increased significantly (P < 0.05) during the storage. Putrescine and cadaverine was the dominant biogenic amines while tryptamine was not detected during the storage. In addition, putrescine, cadaverine and hypoxanthine were highly related to storage time and total viable counts (r(2), 0.876-0.962), indicating that they can be good biomarkers for quality assessment of vacuum-packed minced sturgeon stored at 4 °C.

CONCLUSION

In this study, key biochemical and microbiological attributes were established to monitor the spoilage and shelf life of vacuum-packed sturgeon. These results could help to establish better cold storage management of minced sturgeon products under commercial conditions.

Active and intelligent packaging systems for a modern society

Active and intelligent packaging systems are continuously evolving in response to growing challenges from a modern society. This article reviews: (1) the different categories of active and intelligent packaging concepts and currently available commercial applications, (2) latest packaging research trends and innovations, and (3) the growth perspectives of the active and intelligent packaging market. Active packaging aiming at extending shelf life or improving safety while maintaining quality is progressing towards the incorporation of natural active agents into more sustainable packaging materials. Intelligent packaging systems which monitor the condition of the packed food or its environment are progressing towards more cost-effective, convenient and integrated systems to provide innovative packaging solutions. Market growth is expected for active packaging with leading shares for moisture absorbers, oxygen scavengers, microwave susceptors and antimicrobial packaging. The market for intelligent packaging is also promising with strong gains for time-temperature indicator labels and advancements in the integration of intelligent concepts into packaging materials.

Use of antimicrobial films and edible coatings incorporating chemical and biological preservatives to control growth of Listeria monocytogenes on cold smoked salmon

The relatively high incidence of Listeria monocytogenes in cold smoked salmon (CSS) is of concern as it is a refrigerated processed food of extended durability (REPFED). The objectives of this study were to compare and optimize the antimicrobial effectiveness of films and coatings incorporating nisin (Nis) and sodium lactate (SL), sodium diacetate (SD), potassium sorbate (PS), and/or sodium benzoate (SB) in binary or ternary combinations on CSS. Surface treatments incorporating Nis (25000 IU/mL) in combination with PS (0.3%) and SB (0.1%) had the highest inhibitory activity, reducing the population of L. monocytogenes by a maximum of 3.3 log CFU/cm(2) (films) and 2.9 log CFU/cm(2) (coatings) relative to control samples after 10 days of storage at 21°C. During refrigerated storage, coatings were more effective in inhibiting growth of L. monocytogenes than their film counterparts. Cellulose-based coatings incorporating Nis, PS, and SB reduced the population of L. monocytogenes, and anaerobic and aerobic spoilage flora by a maximum of 4.2, 4.8, and 4.9 log CFU/cm(2), respectively, after 4 weeks of refrigerated storage. This study highlights the effectiveness of cellulose-based edible coatings incorporating generally regarded as safe (GRAS) natural and chemical antimicrobials to inhibit the development of L. monocytogenes and spoilage microflora thus enhancing the safety and quality of CSS.

Enhancing stability of essential oils by microencapsulation for preservation of button mushroom during postharvest

Fresh button mushrooms (Agaricus bisporus L.) are sensitive to browning, water loss, and microbial attack. The short shelf-life of mushrooms is an impediment to the distribution and marketing of the fresh product. Essential oils outstand as an alternative to chemical preservatives and their use in foods meets the demands of consumers for natural products. To resolve controlled release of oil and increase in antioxidant and antimicrobial activities, the oil was incorporated into microcapsules. Effects of microcapsulated thyme (Thymus vulgaris L.) and rosemary (Rosmarinus officinalis L.) on quality of fresh button mushroom were compared. Physicochemical qualities were evaluated during 15 days of storage at 4 ± 0.5°C. All treatments prevented product weight loss and decrease in polyphenoloxidase and peroxidase activities during storage. Color and firmness, microbiological analysis, and total phenolic content caused the least change. With use of microencapsulated oils, mushrooms were within acceptable limits during 10 days of storage. Microencapsulated rosemary oil produced the highest beneficial effects and has potential to improve quality of button mushrooms and extend shelf-life.

Biogenic amine and quality changes in lightly salt- and sugar-salted black carp (Mylopharyngodon piceus) fillets stored at 4°C

The effects of low salt and sugar dry-curing on the quality changes of black carp (Mylopharyngodon piceus) fillets stored at 4°C were evaluated by sensory, physical, chemical, and microbiological methods. Fish samples were left untreated (control), or were dry-cured with 1.5% salt (T1) or 1.5% salt+1.2% sugar (T2). Curing treatments reduced chemical changes reflected in HxR, Hx, pH, and total volatile base nitrogen (TVB-N); decreased cooking loss; and increased overall sensory quality of fish (p<0.05) compared to untreated samples. Significantly lower values of cadaverine and putrescine were observed in T1 and T2 compared to the control after the 2nd and 4th day, respectively (p<0.05). There were significant differences (p<0.05) between T1 and T2 for pH, TVB-N, total aerobic counts (TAC), and sensory characteristics. Sensory characteristics were significantly correlated with TAC, TVB-N, putrescine, and cadaverine in all samples (p<0.01).

Trends in the use of natural antioxidants in active food packaging: a review

The demand for natural antioxidant active packaging is increasing due to its unquestionable advantages compared with the addition of antioxidants directly to the food. Therefore, the search for antioxidants perceived as natural, namely those that naturally occur in herbs and spices, is a field attracting great interest. In line with this, in the last few years, natural antioxidants such as α-tocopherol, caffeic acid, catechin, quercetin, carvacrol and plant extracts (e.g. rosemary extract) have been incorporated into food packaging. On the other hand, consumers and the food industry are also interested in active biodegradable/compostable packaging and edible films to reduce environmental impact, minimise food loss and minimise contaminants from industrial production and reutilisation by-products. The present review focuses on the natural antioxidants already applied in active food packaging, and it reviews the methods used to determine the oxidation protection effect of antioxidant active films and the methods used to quantify natural antioxidants in food matrices or food simulants. Lastly consumers' demands and industry trends are also addressed.

Enhancing safety and shelf life of fresh-cut mango by application of edible coatings and microencapsulation technique

Mango pulp is very perishable and so has a short shelf life, which both marketers and consumers would like to be longer. Manually sliced mango was treated by coating opuntia mucilage-rosemary oil (Mu + RO), 2 g rosemary oil microencapsul (ROM), and 2 g (ROM) plus (Mu + RO); the treated mango pieces were placed in plastic trays, and overwrapped with PVDC film and then stored at 6°C. Changes in the quality parameters and activity of peroxidase (POD) enzyme were evaluated for 9 days of storage period. These treatments retarded loss of ascorbic acid and the drop in sensory acceptability, fewer changes in color, decreasing activity POD enzyme. These also inhibited the decay incidence and slowed microbial growth. The (Mu + RO) treatment was more effective in controlling postharvest quality as compared to the (ROM) treatment, but the data reveal that applying the compound treatment effectively prolongs the quality attributes and extends the storage life of sliced mango fruit.

Inactivation of Salmonella enterica serovar Typhimurium and quality maintenance of cherry tomatoes treated with gaseous essential oils

The antimicrobial activity of the essential oils (EOs) from cinnamon bark, oregano, mustard, and of their major components cinnamaldehyde, carvacrol, and allyl isothiocyanate (AIT) was evaluated as a gaseous treatment to reduce Salmonella enterica serovar Typhimurium in vitro and on tomatoes. In vitro tests showed that mustard EO and AIT had the greatest inhibition of Salmonella, followed by cinnamon EO and cinnamaldehyde, while oregano and carvacrol showed the least inhibition. Scanning electron microscopy images of S. Typhimurium on tomatoes suggest that the EOs and their major components damaged the bacteria, and the damage was more obvious after posttreatment storage at 10 °C for 4 and 7 d. Salmonella on inoculated tomatoes was reduced by more than 5 log colony forming units (CFU)/g by mustard EO and AIT, by 4.56 and 3.79 log CFU/g following cinnamon EO and cinnamaldehyde treatments, respectively, and 1.54 and 3.37 log CFU/g after oregano EO and carvacrol treatments, respectively. Mustard EO and AIT induced discoloration, softening, and loss of the vitamin C and lycopene during 21 d of storage at 10 °C, while treatment with cinnamon EO and cinnamaldehyde did not result in significant changes in tomato quality. Tomatoes treated with oregano EO had better quality than nontreated samples after storage. Therefore, treatment with cinnamon and oregano EO and their major components appeared to be feasible for inactivation of Salmonella on tomatoes and maintaining quality.

Formation of biogenic amines in crucian carp (Carassius auratus) during storage in ice and at 4°C

The formation of eight biogenic amines (BAs), total volatile base nitrogen (TVB-N), aerobic plate counts (APC), and sensory evaluation in crucian carp (Carassius auratus) during storage in ice and at 4°C were investigated. The sum of contents of all eight biogenic amines (SBA) in crucian carp increased from 49.82 to 197.09 mg/kg on day 36 when stored in ice and from 49.82 to 219.35 mg/kg on day 24 when stored at 4°C. TVB-N content increased with storage time; good relationships between TVB-N content and SBA were observed during storage in ice and at 4°C (R(2) = 0.95 and 0.93, respectively). APC of all samples significantly (P < 0.05) increased with storage time in the first 12 days and toward the end of the storage period, there were only minor changes; good relationships between APC and SBA were observed during storage in ice and at 4°C (R(2) = 0.96 and 0.58, respectively). According to sensory evaluation results, the crucian carp became unacceptable on days 24 and 16 during storage in ice and at 4°C, respectively. Putrescine and tyramine contents could be good quality evaluation indices for crucian carp during storage.

Quality enhancement in refrigerated red drum (Sciaenops ocellatus) fillets using chitosan coatings containing natural preservatives

The present work was undertaken to examine the influence of grape seed extract (GS) and tea polyphenols (TP), as natural preservatives, combined with chitosan (Ch), on the quality of red drum (Sciaenops ocellatus) fillets during refrigerated storage. Two different treatments (Ch+GS and Ch+TP) and a control were prepared. The samples were stored (4 ± 1°C) for 20 days and the sampling was done at 0, 4, 8, 12, 16, 20 days. Microbiological, physicochemical and sensory attributes were periodically assessed. The results indicated that the two pretreatments could more effectively maintain quality and could extend the shelf life by 6-8 days compared with the control group during refrigerated storage.

Efficacy of the application of a coating composed of chitosan and Origanum vulgare L. essential oil to control Rhizopus stolonifer and Aspergillus niger in grapes (Vitis labrusca L.)

This study evaluated the efficacy of the combined application of chitosan (CHI) and Origanum vulgare L. essential oil (OV) in the inhibition of Rhizopus stolonifer URM 3728 and Aspergillus niger URM 5842 on laboratory media and on grapes (Vitis labrusca L.) and its influence on the physical, physicochemical and sensory characteristics of the fruits during storage (25 °C, 12 days and 12 °C, 24 days). The application of mixtures of different CHI and OV concentrations (Minimum Inhibitory Concentration - MIC, 1/2 MIC and 1/4 MIC) inhibited the mycelial growth of the test fungi. The application of CHI and OV at sub-inhibitory concentrations (CHI 1/2 MIC + OV 1/4 MIC; CHI 1/2 MIC + OV 1/2 MIC) inhibited spore germination and caused morphological changes in fungal spores and mycelia, in addition to inhibiting the growth of the assayed fungi strains in artificially infected grapes as well as the autochthonous mycoflora of grapes stored at both room and cold temperature. In general, the application of a coating composed of CHI and OV at sub-inhibitory concentrations preserved the quality of grapes as measured by their physical and physicochemical attributes, while some of their sensory attributes improved throughout the assessed storage time. These results demonstrate the potential of the combination of CHI and OV at sub-inhibitory concentrations to control post-harvest pathogenic fungi in fruits, in particular, R. stolonifer and A. niger in grapes.

The Effects of Zataria multiflora Boiss Essential Oil and Nisin on Chemical Characteristics of Rainbow Trout Fillet Stored at 4 °C

This study evaluated the effects of Zataria multiflora essential oil (EO) and nisin on fresh rainbow trout fillets during storage at 4 °C. Treatments included the following: A (control samples without EO and nisin), E1 (treated samples with 0.2% EO), E2 (treated samples with 0.4% EO), N (treated samples with 150 IU nisin/g), E1N (treated samples with 0.2% EO and nisin) and E2N (treated samples with 0.4% EO and nisin). Chemical and oxidation changes were investigated in this study as the functions of treatment and storage time. E1N and E2N had better effects on oxidation changes and maintaining values of peroxide value and thiobarbituric acid than A, E1, E2 and N treatments. Lower total volatile base nitrogen was found in E2N than in other treatments during storage time.