Inhibition of quality loss in chilled megrim (Lepidorhombus whiffiagonis) by employing citric and lactic acid icing

This study focuses on the quality retention of megrim (Lepidorhombus whiffiagonis) during chilled storage. Aqueous solutions of two different concentrations of citric (CA) and lactic (LA) acids were employed as icing media (0.125% CA–0.050% LA and 0.175% CA–0.050% LA, respectively; w/v). The effects of each solution on microbial activity, lipid damage and sensory acceptance were monitored for up to 13 days of storage. Lower (P < 0.05) bacterial growth was detected according to microbiological (aerobe and psychrotroph counts) and chemical (trimethylamine‐N and pH) assessments, which led to an enhancement of sensory appreciation. Whereas control fish were determined as unacceptable at day 13, the acid‐iced fish were still acceptable at that time. Concerning lipid damage, an inhibitory effect (P < 0.05) on fluorescent compound formation was observed in the acid‐iced fish. Present results allow to conclude that the use of a CA–LA icing system can provide a profitable strategy to obtain higher quality chilled fish.     

Effect of a two‐step natural organic acid treatment on microbial activity and lipid damage during blue whiting (Micromesistius poutassou) chilling

Quality loss inhibition in chilled blue whiting (Micromesistius poutassou) was investigated. For it, a natural organic acid‐mixture including ascorbic, citric and lactic acids was applied in a two‐step processing strategy: (i) as an aqueous dipping medium previous to chilling storage and, (ii) included in the flake ice employed as chilling system. As a result of the acid‐mixture addition, a partial inhibition of microbial and biochemical mechanisms involved in the quality loss was obtained. Thus, aerobe and psychrotrophe counts in treated fish showed lower ranges (2.07–4.15 and 2.43–4.39 log CFU g^?1, respectively) than control fish (2.64–5.83 and 2.30–5.30 log CFU g^?1, respectively). Sensory analysis revealed that treated fish was still acceptable at the end of the experiment (day 9), while control fish was rejected at this time. Lipid hydrolysis (free fatty acid formation) proved to be more limiting of fish quality than lipid oxidation (peroxide and thiobarbituric acid‐reactive substance formation).     

Effect of a natural organic acid-icing system on the microbiological quality of commercially relevant chilled fish species

Natural preservative organic acids (ascorbic, citric and lactic acids) were used to prepare a novel organic acid-flake icing system for the chilled preservation of hake (Merluccius merluccius), megrim (Lepidorhombus whiffiagonis) and angler (Lophius piscatorius). The icing system was prepared with two different concentrations of a commercial acid mixture-formula containing the three organic acids at 800 mg/kg and 400 mg/kg (C-800 and C-400 batches, respectively). Aerobic mesophiles, psychrotrophs, proteolytic bacteria, trimethylamine and pH were evaluated and the results compared with sensory analyses. Significantly (P < 0.05) lower counts of mesophiles were found for hake and megrim in the C-800 and C-400 batches compared with the control batch. In the case of angler, significantly (P < 0.05) lower counts of mesophiles, psychrotrophs and proteolytic microorganisms (P < 0.05) were found for fish stored in the C-800 icing conditions. Both C-400 and C-800 megrim batches exhibited significantly (P < 0.05) lower pH values than the control batch, and this result was also observed in the C-800 angler batch. Sensory analysis confirmed that the shelf lives of the three fish species in the C-800 batch were extended. According to the parameters assessed, storage of hake, megrim and angler in the proposed ice system better protects their microbial and sensory qualities.     

Combined Effect of Icing Medium and Red Alga <Emphasis Type="Italic">Gracilaria verrucosa</Emphasis> on Shelf Life Extension of Indian Mackerel (<Emphasis Type="Italic">Rastrelliger kanagurta</Emphasis>)

Flake ice refrigeration is a conventional but commonly employed technique to slow down fish spoilage and deterioration of nutritional values and sensory properties during chilled storage. In the present study, a methanolic extract of red alga Gracilaria verrucosa was characterised, and functional groups, such as alkenes, aldehydes, nitriles, galactans and galactose-4-sulphate were found. Subsequent identification of active compounds revealed the presence of potent preservative agents, such as butylated hydroxytoluene, sulfurous acid, 1,2-propanediol, benzeneacetic acid, cyclononasiloxane and tetracosamethyl-cyclododecasiloxane. The effect of incorporating G. verrucosa at two different concentrations (0.67 and 2.5 g lyophilised alga/L aqueous solution) in the icing medium was tested for the preservation of Indian mackerel (Rastrelliger kanagurta), compared to preservation in traditional ice prepared only from water. Microbial, chemical and sensory qualities were monitored in Indian mackerel chilled in ice with and without G. verrucosa during 15 days storage period. Inhibitory effects (p?<?0.05) on the microbial proliferation (mesophilic and psychrophilic bacteria) and chemical markers of fish deterioration (pH, TVB-N, TMA-N and biogenic amines) were evidenced for ice containing both concentrations of G. verrucosa, respectively, relative to the control medium. The sensory score acceptability limit reached 11 days for Indian mackerel stored in traditional ice and 15 days for Indian mackerel stored in ice with G. verrucosa extract. Thus, the icing medium containing G. verrucosa extract improves the quality and safety of Indian mackerel during storage and can be explored by the seafood industry as a biopreservative.     

Quality Enhancement of Chilled Fish by Including Alga <Emphasis Type="Italic">Bifurcaria bifurcata</Emphasis> Extract in the Icing Medium

Bifurcaria bifurcata is a widely extended brown macroalga, whose antimicrobial and antioxidant properties have previously been described. In this study, ethanolic extracts of B. bifurcata were included in the icing medium employed for the chilled storage of megrim (Lepidorhombus whiffiagonis). For it, two different concentrations of this brown macroalga extract (0.67 and 2.50 g lyophilized alga L^?1 aqueous solution; B-1 and B-2 batches, respectively) were tested for a 14-day storage. The effect of the alga extract was compared with a counterpart batch stored in traditional ice prepared only from water (B-0 batch). Significant (p < 0.05) inhibitions of microbial activity (aerobes, psychrotrophs, lipolytic bacteria, proteolytic bacteria and Enterobacteriaceae) as well as of pH and trimethylamine formation were observed as a result of the incorporation of the alga extract in the icing medium, being this effect especially relevant in the B-2 batch. Concerning lipid damage development, a significantly (p < 0.05) lower formation of free fatty acids (lipid hydrolysis development) and of fluorescent compounds (tertiary lipid oxidation development) in samples corresponding to both alga-including batches could also be observed; this inhibitory effect was more intense in fish belonging to the B-2 batch. The icing medium proposed in this work constitutes a promising strategy in order to apply algae extracts to enhance fish quality retention during the different steps of storage and commercialization of marine species.     

Superchilled,chilled and frozen storage of Atlantic mackerel (Scomber scombrus) fillets – changes in texture,drip loss,protein solubility and oxidation

Changes in quality characteristics in relation to protease activity and protein oxidation in chilled, superchilled and frozen mackerel fillets during storage were studied. The solubility of sarcoplasmic proteins was quite stable in mackerel samples for all storage experiments, whereas the solubility of myofibrillar proteins decreased in both superchilled and frozen samples. A significant correlation (r = 0.983, P < 0.05) between the increased activity of cathepsin B+L in chilled fillets and softening of the fish flesh during storage was revealed. Contrary with chilled samples, the texture of superchilled mackerel fillets became tougher along the storage period, which can be explained by a higher rate of myofibrillar oxidation (r = 0.940, P < 0.05). The hardness and drip loss decreased slightly at the end of frozen storage. Superchilling preserved the quality of mackerel fillets with the least side effects in relation to protein solubility, drip loss and softening of the fish tissue as compared to chilled and frozen storage.     

Impact of icing systems with aqueous,ethanolic and ethanolic‐aqueous extracts of alga Fucus spiralis on microbial and biochemical quality of chilled hake (Merluccius merluccius)

The study focuses on the impact of icing systems with aqueous (AQ batch), ethanolic (ET batch) and ethanolic‐aqueous (ET‐AQ batch) extracts of alga Fucus spiralis on the microbial and biochemical quality of chilled hake (Merluccius merluccius). After a 13‐day storage, comparison with fish kept under traditional ice proved a significant (P < 0.05) antimicrobial effect against aerobes, psychrotrophs, proteolytic and lipolytic bacteria, derived of the presence of F. spiralis ethanolic extracts in the icing medium (ET and ET‐AQ batches). Additionally, an inhibitory effect of both ethanol extracts was also obtained concerning lipid oxidation development (i.e. secondary and tertiary lipid oxidation compounds). Additionally, lipid damage assessment showed lower mean values in tertiary oxidation compound formation in hake belonging to the ET‐AQ batch throughout the whole storage period. Present research indicates that ET‐AQ ice condition can lead to a marked quality and safety enhancement as well as to profitable commercial value increases.     

NONVOLATILE ORGANIC ACIDS IN GUAVA

ABSTRACT— The nonvolatile organic acids of guava were extracted and isolated. TLC of the acids showed the presence of 6 acids, 5 of the acids identified as lactic, malic, citric, ascorbic and galacturonic. GLC of the methyl esters of the guava acids confirmed the presence of malic, citric and lactic acid. Quantitative determinations using succinic acid as an internal standard showed citric and malic acid to be present in almost equal amounts and lactic acid in much lesser amount in cultivated guavas. In wild guavas, citric acid was the predominant acid, with lesser amounts of malic and lactic acids.     

Inhibition of chemical changes related to freshness loss during storage of horse mackerel (Trachurus trachurus) in slurry ice

Slurry ice is a biphasic system consisting of small spherical ice crystals surrounded by seawater at subzero temperature. Its employment was evaluated in the present work as a new chilled storage method for whole horse mackerel (Trachurus trachurus) and compared with traditional flake icing. Different chemical analyses (nucleotide degradation, lipid hydrolysis and oxidation, interaction compounds formation and electrophoretic protein profiles) related to quality loss were checked and compared to sensory evaluation. An inhibitory effect on quality loss mechanisms was observed for the slurry ice treatment, according to the assessment of the K value, free fatty acid content, thiobarbituric acid index, fluorescent compounds formation and sarcoplasmic protein profiles. The sensory analysis showed a higher shelf-life time for fish treated under slurry icing than for flake iced fish (15 and 5 days, respectively). Results confirm the practical advantages of using slurry ice as a chilling storage method. According to the inhibition of lipid hydrolysis and oxidation obtained, the employment of slurry ice on relatively fat fish species is recommended to obtain safer and higher quality fish products.     

Effect of previous chilled storage on rancidity development in frozen horse mackerel (Trachurus trachurus)

Rancidity development during frozen storage (?20 °C) of an underutilised medium‐fat‐content fish species, horse mackerel (Trachurus trachurus), was studied. Special attention was given to the effect of previous chilled storage (0, 1, 3 and 5 days) on the quality of the frozen fish. For this, chemical (free fatty acid and conjugated diene contents; peroxide value, PV; thiobarbituric acid index, TBA‐i; fluorescent compound formation) and sensory (rancid odour and taste) analyses were carried out. Hydrolytic rancidity showed an increase with frozen storage time; however, no effect of previous chilling time was observed on the frozen product. Oxidative rancidity measured by chemical (PV, TBA‐i and fluorescence) and sensory (odour and taste) indices increased with frozen storage time and also with previous chilling time. Satisfactory quality was maintained up to 7 months of frozen storage of horse mackerel provided that a short chilling time (not longer than 3 days) was employed. © 2002 Society of Chemical Industry     

RELATIONSHIPS OF COLOR, VISCOSITY, ORGANIC ACID PROFILES AND ASCORBIC ACID CONTENT TO ADDITION OF ORGANIC ACIDS AND SALT IN TOMATO JUICE

Malate and citrate acidified juices produced statistically similar results for pH and titratable acidity (TA), but these acidified juices were significantly different from nonacidified juice when comparing pH and TA. During storage time, the pattern of the pH and TA curves, regardless of acidification, were similar. Salted juice exhibited a significantly higher ascorbic acid content and greater viscosity than did the unsalted juice during storage. The organic acids citric, lactic, malic, and pyrocarboxylic increased immediately after heat processing for commercial sterility, while the presence of salt in this juice lowered these same organic acids. There was minimal correlation of the organic acids or the summation of the acids equivalents of all the organic acids to the titratable acidity or pH of the juices. Juices acidified with malate or citrate did not consistently display an increased level of that specific acid after processing and storage.     

Quality of Norway lobster (Nephrops norwegicus) treated with a 4-hexylresorcinol-based formulation

In the present work, the effect on biochemical indexes and microbial growth was studied in Norway lobster (Nephrops norwegicus), using a formulation containing 4-hexylresorcinol (0.1 and 0.05%) in combination with organic acids (citric, ascorbic and acetic) and chelating agents (ethylenediaminetetraacetic acid [EDTA] and di-sodium di-hydrogen pyrophosphate [PPi]). Lobsters treated with 4% of a commercial formula based on sulphites were used for control purposes. The treatment with 4-hexylresorcinol-based formulations delayed the increase in K-value and total volatile bases, while evolution of pH and trimethylamine was similar regardless of the treatment. No relation was found between biochemical and microbiological indexes. Regarding microflora, although commercial sulphites slightly slowed the growth of seafood spoiler organisms, as Shewanella putrefaciens and luminescent colonies, these organisms were not found in a very high number (∼6 log cfu/g) at the end of storage. Moreover, the formulation containing 4-hexylresorcinol 0.1% appeared to stimulate the growth of lactic acid bacteria. The sensory quality of lobster, in terms of melanosis, remained with a good appearance for 12 days. Formulations based on 4-hexylresorcinol preserved the quality and could therefore replace the traditional sulphites during storage of Norway lobster.     

Use of organic acids to inactivate Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on organic fresh apples and lettuce

Abstract: This study was undertaken to investigate the antimicrobial effect of organic acids against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on whole red organic apples and lettuce. Several studies have been conducted to evaluate organic acids as sanitizers. However, no studies have compared antimicrobial effects of various organic acids on organic fresh produce, including evaluation of color changes of produce. Apples and lettuce were inoculated with a cocktail of 3 strains each of 3 foodborne pathogens provided above and treated with 1% and 2% organic acids (propionic, acetic, lactic, malic, and citric acid) for 0, 0.5, 1, 5, and 10 min. With increasing treatment time and acid concentration, organic acid treatments showed significant reduction compared to the control treatment (distilled water), and differences in antimicrobial effects between organic acids were observed. After 10 min of treatment with 1% and 2% organic acids in apples, propionic (0.92 to 2.75 log reduction), acetic (0.52 to 2.78 log reduction), lactic (1.69 to >3.42 log reduction), malic (1.48 to >3.42 log reduction), and citric acid (1.52 to >3.42 log reduction) exhibited significant (P < 0.05) antibacterial effects against 3 foodborne pathogens compared to the control treatment. In lettuce, propionic (0.93 to 1.52 log reduction), acetic (1.13 to 1.74 log reduction), lactic (1.87 to 2.54 log reduction), malic (2.32 to 2.98 log reduction), and citric acid (1.85 to 2.86 log reduction) showed significant (P < 0.05) effects compared to the control treatment. Changes in sample color subjected to organic acids treatment were not significant during storage. Practical Application: It is suggested that organic acids have a potential as sanitizers for organic fresh produce. These data may help the organic produce industry provide safe fresh produce for consumers.     

Diffusion of citric and ascorbic acids in pre-peeled potatoes and their influence on microbial growth during refrigerated storage

The most common chemical preservatives used to inhibit both enzymatic browning and microbial growth in pre-peeled potatoes are sodium sulphite and bisulphite. Since 1987 the FDA has limited their use as food ingredients; consequently, during recent years the tendency to replace sulphites by GRAS chemical additives such as citric and ascorbic acids has become stronger. In the present work, surface colour variations, exudate production and microbial growth were analysed on pre-peeled potatoes treated with citric and ascorbic acids. These preservatives were applied individually and as mixtures; shelf-life was extended and microbiologically safe products were obtained. Mathematical models were solved to analyse the diffusion of these acids during immersion and storage periods in order to determine the concentration profiles within the product and to predict the surface concentration to which the microorganisms are exposed.     

ANTIMICROBIAL PROPERTIES OF LAURICIDIN IN MECHANICALLY DEBONED CHICKEN, MINCED FISH AND CHICKEN SAUSAGE

Aerobic plate counts on Plate Count Agar at 25°C were used to determine the time required to reach a microbial spoilage level of 1.0 × 10⁷ C.F.U./g, for mechanically deboned chicken meat, minced fish and chicken sausage stored at 2°C. The storage times were 5, 8 and 9 days, respectively. Addition of citric acid (0.2%), ascorbic acid (0.2%) or lauricidin (250 ppm) alone extended the shelf-life by 0–2 days. The combination of lauricidin and citric acid or lauricidin and ascorbic acid extended the time required to reach a microbial spoilage level for mechanically deboned chicken meat by as much as 7 days, minced fish by as much 4 days and chicken sausage by 8 days.     

Sensory,microbial and chemical effects of a slurry ice system on horse mackerel (Trachurus trachurus)

Slurry ice, a biphasic system consisting of small spherical ice crystals surrounded by seawater, was evaluated in parallel with flake ice for the storage of horse mackerel (Trachurus trachurus). Storage in slurry ice led to a significant enhancement of shelf life (5 days for flake ice to 15 days for slurry ice), better control of pH and lower counts of total aerobes and proteolytic and lipolytic bacteria, these reaching an average difference between batches of 2, 1.43 and 1.98 log units respectively after 8 days of storage. Storage in slurry ice also involved a significantly slower formation of total volatile basic nitrogen and trimethylamine after 8 days of storage. Staphylococcus xylosus and Proteus penneri were identified as the leading proteolytic and lipolytic organisms in horse mackerel muscle. Storage of horse mackerel in slurry ice enhances the shelf life of this medium‐fat fish species through better maintenance of sensory and microbiological quality. Copyright © 2004 Society of Chemical Industry     

葡萄酒酿造过程中有机酸变化规律研究

采用离子色谱法分析了葡萄酒中9种有机酸含量。通过对赤霞珠葡萄酒发酵过程中主要有机酸变化分析,研究其从葡萄汁到原酒的酿造过程中有机酸含量变化规律和量变的幅度。结果表明,葡萄酒中有机酸主要有酒石酸、苹果酸、乳酸、柠檬酸和琥珀酸,葡萄汁经发酵产生了乳酸、乙酸和琥珀酸。酿造过程中酒石酸、苹果酸、抗坏血酸和柠檬酸含量一直呈下降趋势;草酸和琥珀酸含量先增高后减少,乳酸含量一直呈上升趋势。乙酸是葡萄酒酒精发酵的主要副产物,含量为0.2～0.3 g/L。     

Deterioration due to delayed icing and its impacts on the nutritional quality of Malabar travally (Carangoides malabaricus)

Effect of delayed icing of the fish Carangoides malabaricus was assessed using chemical and microbial methods to determine the impacts on the nutritional quality and sensory changes. The shelf life of the fishes iced immediately after harvest had a shelf life of 18 days, whereas the delay of icing for 4, 6, 8 and 10 h shortened the shelf life to 14, 10, 6 and 3 days respectively. The spoilage indicators, such as trimethylamine nitrogen, Total volatile basic nitrogen, free fatty acids, peroxide value, thiobarbituric acid and pH values, significantly increased (P < 0.05) during the storage period of fishes with delayed icing. The total bacterial count also increased during the storage period and due to quality deterioration, the protein and lipid contents were found significantly low (P < 0.05). This study showed that chemical and microbial changes of the sample are well correlated with nutritional and sensory qualities so that immediate icing is important for maintaining the quality and shelf life of C. malabaricus.     

复合防腐剂在冰鲜鸭肉保鲜中的应用

以番鸭的胴体分割肉为原料,经过不同的保鲜液浸泡处理后,进行真空包装,研究不同保鲜剂对冰鲜鸭保藏性能的影响.通过感官指标、理化指标、微生物指标的测定,结果表明:乳酸链球菌素(Nisin)、乙酸、乳酸和抗坏血酸的配合性使用,能有效延长冰鲜鸭肉的冷藏保鲜时间;冰鲜鸭保藏的最佳工艺参数为Nisin0.05%+乙酸2%+乳酸10%+抗坏血酸2%.     

Microbial changes and growth of Listeria monocytogenes during chilled storage of brined shrimp (Pandalus borealis)

Thirteen storage trials and ten challenge tests were carried out to examine microbial changes, spoilage and the potential growth of Listeria monocytogenes in brined shrimp (Pandalus borealis). Shrimp in brine as well as brined and drained shrimp in modified atmosphere packaging (MAP) were produced and studied. Different recipes were used to study the effect of preserving parameters (organic acids, pH and NaCl) on growth of microorganisms and shelf life at 7-8 degrees C or 12 degrees C. Particularly, brines with different concentrations of (i) benzoic, citric and sorbic acids or (ii) acetic, citric and lactic acids were studied. Furthermore, the effect of adding diacetate to brined shrimp was evaluated. A single batch of cooked and peeled shrimp was used to study both industrially and manually processed brined shrimp with respect to the effect of process hygiene on microbial changes and the shelf life of products. Concentrations of microorganisms on newly produced brined shrimp from an industrial scale processing line were 1.0-2.3 log (CFU g(-1)) higher than comparable concentrations in manually processed samples. This resulted in a substantially shorter shelf life and a more diverse spoilage microflora of the industrially processed brined shrimp. In addition, shelf life of brined shrimp was affected by the types and concentrations of organic acids and by the storage temperature as expected. The effect of MAP was less pronounced. Eighty-two isolates from the spoilage microflora of brined shrimp were identified and they included 53 lactic acid bacteria, 6 coagulase negative Staphylococcus spp., 18 Pseudomonas fluorescens and 5 yeast isolates. After storage at 7 degrees C, P. fluorescens, Enterococcus-like isolates, E. malodoratus, Carnobacterium maltaromaticum, coagulase negative Staphylococcus spp. and Lactobacillus sakei constituted the dominating microflora of shrimp in brines that contained benzoic, citric and sorbic acids as preservatives. L. sakei dominated the spoilage microflora of brined and drained MAP shrimp, and of brined shrimp preserved using acetic, citric and lactic acids, irrespective of packaging conditions. Shrimp in brine with benzoic, citric and sorbic acids prevented growth of L. monocytogenes during more than 40 days at 7 degrees C when the preserving parameters resembled those of commercial products. However, small changes in the preserving parameters and, particularly, reduced concentrations of benzoic acid led to growth of L. monocytogenes in brined shrimp. The present study provides significant new information on microbial changes, shelf life and growth of L. monocytogenes in brined shrimp. This information can facilitate development of new and safe brined shrimp products.