Effect of advanced chilling methods on lipid damage during sardine (Sardina pilchardus) storage

Slurry ice is a biphasic system consisting of small spherical ice crystals surrounded by seawater at subzero temperature. Its effect on lipid damage (hydrolysis and oxidation) was evaluated during the chilled storage of a fatty fish species, sardine (Sardina pilchardus). Slurry ice treatment was checked alone and in combination with ozone and compared to traditional flake icing during a 22‐day storage. Different lipid damage indices (free fatty acids, FFA; peroxide value, PV; thiobarbituric acid index, TBA‐i; fluorescent compounds, FR) were checked and compared to sensory assessment and nucleotide degradation (K value). According to lipid hydrolysis (FFA) and oxidation (PV and FR) developments, slurry ice showed an inhibitory effect (p <0.05) on lipid damage during storage, as well as an inhibition of nucleotide autolytic degradation. Ozonised slurry ice did not provide differences (p >0.05) from slurry ice alone when considering lipid hydrolysis, nucleotide degradation and some lipid oxidation indices (PV and FR), although a higher (p <0.05) TBA‐i was observed at day 22 of storage when compared to flake ice and slurry ice treatments. However, a lower (p <0.05) fluorescence development was observed for fish treated under ozonised slurry ice when compared to traditionally iced fish. Sensory assessment showed a higher shelf life for fish samples treated under ozonised slurry ice than for their counterparts under slurry ice (15 d versus 12 d), while flake icing led to a far shorter shelf life (5 d). According to sensory and biochemical (lipid matter and nucleotide) analysis, slurry ice has proved to be a promising technology for damage inhibition and quality retention in a fatty fish species such as sardine. Ozonised slurry ice was also shown to be useful, since a longer shelf life was obtained in the present experiment and a pro‐oxidant effect of ozone on sardine lipids was not proved.     

Effects of rainbow trout freshness on n‐3 polyunsaturated fatty acids in fish offal

The effects of rainbow trout cold storage on the quality of offal left after fish processing to fillets with skin were determined. The intact farmed rainbow trout were kept at 2 °C in ice for 0, 4, 7, and 14 days of storage. The offal was, immediately after processing, frozen at ?20 °C and analysed after a month‐long frozen storage; fillets (non‐frozen) were analysed as well. Non‐protein nitrogen, volatile bases, trimethylamine, lipid oxidation (peroxide value, anisidine value, UV‐VIS spectra, and fluorescence) and fatty acid composition were determined. The offal consists in 15% of protein and in about 20% of chloroform/methanol‐extractable lipids, with n‐3 polyunsaturated fatty acids (n‐3 PUFA) accounting for 20.37 ± 1.25% of the fatty acids. The fish storage duration was found to exert a significant (p = 0.05) effect on the changes in lipids and nitrogen compounds. No losses of long‐chain n‐3 PUFA in the offal were detected during the 2 wk of storage in ice plus 1 month at ?20 °C. The rainbow trout offal is a valuable – rich and stable – source of n‐3 PUFA.     

Influence of Temperature Stress on Lipid Stability of Atlantic Herring (<Emphasis Type="Italic">Clupea harengus</Emphasis>) Muscle During Frozen Storage

Unstable conditions are commonly encountered during industrial storage and transportation of frozen fish. Temperature stress and fluctuations may increase the amount of unfrozen water in the muscle and enzymatic activity and lipid oxidation can thus still take place during frozen storage. The aim of this study was to investigate the changes of characteristics of different muscle types of herring at unstable modelled conditions during storage and transportation. Compositional changes, lipid oxidation and lipid hydrolysis were monitored in light and dark muscle of Atlantic herring (Clupea harengus), during frozen storage, as affected by temperature stress (samples were stored at ? 25 °C for 2 months, then stressed at ? 12 °C for 1 month, followed by storage at a stable ? 25 °C for the remaining storage duration), and compared to samples stored at a stable ? 25 °C for 14 months. The dark muscle was more sensitive to lipid oxidation than the light muscle, leading to faster degradation. Increased lipid oxidation and lipid hydrolysis were observed in temperature‐stressed samples of both muscle types. The study demonstrated the importance of avoiding temperature stress during industrial frozen storage and transportation to improve the quality and shelf life of frozen herring products. Removal of dark muscle by deep skinning could benefit both processors and customers regarding the shelf life and nutritional value of the light herring muscle.     

Preservative effect of an organic acid‐icing system on chilled fish lipids

This study provides a first approach concerning a novel chilling strategy, which employs a mixture of different preservative organic acids (ascorbic, citric and lactic) in the icing medium. Thus, ice prepared from water including two different concentrations of a commercial acid mixture‐formula (800 and 400 ppm; C‐800 and C‐400 conditions, respectively) were applied as icing system to three important commercial fish lean species (hake, Merluccius merluccius; megrim, Lepidorhombus whiffiagonis; angler, Lophius piscatorius). Lipid oxidation (peroxide value; thiobarbituric acid index; fluorescent compound formation) and hydrolysis (free fatty acid formation) were evaluated throughout the chilling time (up to 12–15 days) and compared to results obtained in fish kept under traditional ice prepared only from water (C‐0 condition); a complementary sensory evaluation was carried out. As a result of employing the C‐800 icing condition, a partial inhibition of lipid oxidation and hydrolysis development was obtained that was accompanied by a shelf life enhancement in all cases. Further research taking into account the complementary action of the present organic acids is envisaged. According to the lipid damage analysis, lipid hydrolysis was a more relevant event than lipid oxidation in all fish species tested.     

Shelf‐life prediction of perilla oil by considering the induction period of lipid oxidation

Kinetic models for the induction period (IP) of lipid oxidation were developed to predict the shelf‐life of perilla oil during storage. The degree of lipid oxidation was measured in terms of peroxide values (PV). The perilla oil was stored in the dark at various temperatures. The IP was measured at the intersection point of two linear lines and in terms of time and PV at the IP. The IP was expressed by an Arrhenius‐like relationship. Before and after the IP, the reaction followed pseudo‐zero‐order kinetics. The oxidation degrees according to storage times were computed by considering the variables, IP and reaction rate constants. The prediction model equation that was developed to determine shelf‐life is more accurate than in previous studies. Conclusively, considering the IP of lipid oxidation is essential for predicting the shelf‐life of perilla oil and is expected to be applicable to other vegetable oils. Practical applications : In kinetic modeling for shelf‐life estimation in terms of lipid oxidation, induction period (IP) is rarely considered. Thus the estimation of peroxide values (PV) from such models might be inaccurate. The IP was observed in perilla oil oxidation and kinetic models involving the IP were developed. This work enables a better estimation of oxidation. Besides, a shelf‐life diagram of perilla oil has been constructed as a valuable tool for quality control in the food industry.     

Development of Lipid Changes Related to Quality Loss During the Frozen Storage of Farmed Coho Salmon (<Emphasis Type="Italic">Oncorhynchus kisutch</Emphasis>)

Lipid changes related to quality loss were evaluated during frozen storage of coho salmon for up to 15 months. Biochemical indices concerning lipid hydrolysis (free fatty acids, FFA) and oxidation (peroxide value, PV; thiobarbituric acid index, TBA-i; fluorescent compounds, FR; polyene index, PI) were determined and compared to sensory (odor and taste) and endogenous antioxidant (tocopherol isomers and astaxanthin) assessments. As a result of the frozen storage, lipid hydrolysis was shown to develop according to the increase in FFA content (p < 0.05). However, most biochemical lipid oxidation indices (PV, TBA-i and FR) led to a low degree of rancidity development (p < 0.05) when compared to other fatty fish species under similar frozen storage conditions. The PI value decreased (p < 0.05) at month 10 but then remained unchanged until the end of the experiment. Rancid odor and taste development were shown to be low throughout the experiment, according to the biochemical indices mentioned above. However, a progressive decrease (p < 0.05) in the original fresh odor and taste of salmon fish flesh occurred with increasing frozen storage time, such that fish samples had the poorest scores by month 15. Endogenous antioxidants were remarkably stable throughout the experiment and which might contribute to the oxidative stability of frozen farmed coho salmon lipids.     

Lipid Composition and State of Oxidation of Fortified Infant Flours in Low‐Income Countries Are Not Optimal and Strongly Affected by the Time of Storage

Food fortification is widely used to address the public health problem of nutrient deficiencies. This study's purpose is to assess the lipid profile and nutritional quality of 13 fortified infant flours (FI) collected “in the field” in Africa and Asia after different periods of storage. The lipid content, fatty acid profiles, lipophilic vitamin content, and lipid oxidation state (peroxide values, secondary oxidation products) are determined. Mycotoxins and packaging materials are also characterized. The lipid content averages 9.1 ± 3.5 g/100 g. Fatty acid profiles are dominated by linoleic (43.3 ± 8.8%), oleic (29.5 ± 7.4%), and palmitic acid (17.8 ± 6.7%) and result in an average ω6/ω3 ratio of 12.2 ± 5.9 but with high values for some FI. Very high overages in vitamins A, D, and E are observed in products stored for short periods (1–6 months), whereas FI stored for more than 12 months has insufficient vitamin content. Lipid oxidation is acceptable but for six products presenting excessive peroxide values. Most products are contaminated by low amounts of mycotoxins but only two FI do not abide by the regulation. A strong correlation between peroxide values, hexanal content, and time of storage is observed. Practical Applications: The expiration dates for FI commercialized in low‐income countries should be shortened from 36 to 12 months so as to guarantee their nutritional quality of these functional foods and to abide by the fortified infant flour legislation. Indeed, FI quality significantly decreases over time of storage. The use of high barrier packaging materials must be generalized, although it is a necessary criterion but not sufficient to ensure the long‐term stability of FI. Special attention should be given to reduce lipophilic vitamin overages and to improve their lipid profile, especially the ω6/ω3 ratio, which has to be lower than 15.     

Lipid autoxidation in ozone‐processed crustacea under cold storage: A treatise

Polyunsaturated fatty acids (PUFAs) substantially present in decapod crustaceans, are largely responsible for the progression of lipid autoxidation that directly contribute to subsequent reduction in postharvest quality and shelflife. Even iced storage widely utilized at commercial fisheries is unable to completely slow down this deteriorative process. On the other hand, ozone usage on food as approved by US Food and Drug Administration (FDA) has over the years improved its potential applications. This is seen in recent times through the manufacture of domestic facilities that safely discharge ozone and increasingly commercially available for home use. While lipid autoxidation remains an increasing challenge to fishery product shelf life, recent studies have showed ozone treatment to be a potential preservative candidate for reducing lipid damage in a crustacean product such as shrimp.     

Quality enhancement of canned sardine (Sardina pilchardus) by a preliminary slurry ice chilling treatment

The slurry ice technology has shown wide advantages when employed as a chilling method for marine species instead of the traditional flake ice storage. In the present work, the use of slurry ice was evaluated for the first time as a technological treatment prior to the canning processing of fish. Thus, sardine (Sardina pilchardus) specimens were stored in slurry ice for 2 and 5 days and then taken and subjected to canning. Quality assessment of the canned product was performed on the fish muscle and on the coating oil, in comparison with that of a parallel control batch previously stored in flake ice. Analyses included composition (water, lipid and NaCl contents), physical properties (firmness, cohesivity), volatile amine formation (total and trimethylamine), lipid oxidation development (anisidine value, polyene index, α‐tocopherol content and Rancimat oxidative stability) and interaction compounds formation (fluorescence assessment). An inhibition of lipid oxidation development (p <0.05) was obtained in canned sardine when applying slurry ice as a preliminary chilling storage system. The present work opens the way to the use of slurry ice instead of flake ice as a preliminary treatment of fish material prior to the canning process.     

Electron spin resonance spectroscopy for determination of the oxidative stability of food lipids

Evaluation of the oxidative stability of food lipids based on the tendency of formation of radicals is shown to be possible using electron spin resonance (ESR) spectroscopy and the spin-trapping technique. Induction time can be determined for mildly accelerated conditions (50°C for lipid fraction from mayonnaise enriched with fish oil), and the length of the induction time decreases during storage and γ-tocopherol depletion. The protection by ethylenediaminetetraacetic acid against initiation of lipid oxidation is also detected in the new assay. For more oxidatively stable lipids (butter, rapeseed oil, dairy spread) the mildly accelerated conditions can be used in the assay, provided that difference in signal height for fixed times replaces determination of induction time. ESR spin trapping provides a sensitive method for evaluating the oxidative stability of food lipids. Detection of radicals in the lipid as an early event in oxidation allows mild conditions to be used, and future experiments should also include sensory evaluation in relation to determination of practical shelf life.     

Investigation of Lipid Oxidation in High- and Low-Lipid-Containing Topical Skin Formulations

Lipid oxidation can impact the odour of skin care products during storage. A study was conducted to identify and monitor representative markers for lipid oxidation in skin care products over time. Four lip care formulations and three skin care formulations with different lipid contents were stored at various cosmetic industry‐relevant conditions for 84 days. The skin care products were analysed for lipid hydroperoxides and secondary volatile oxidation products. A trained sensory panel performed an odour difference (triangle) test and odour‐profiled the products to detect and describe odour changes during storage. Several potential markers for lipid oxidation were identified. In skin care formulations, peroxide value (PV) analysis was a useful marker for lipid oxidation if the product was exposed to light during storage, but no clear changes were observed for PV in samples stored under other conditions. Furthermore, concentrations of several secondary volatile oxidation products increased during storage, and the highest increase was observed for products exposed to light. Pentanal and heptanal were found to be reliable markers for secondary volatile oxidation products in the skin care formulations (especially during exposure to light), whereas in the lip care formulations the best candidates were pentanal (especially during exposure to light and iron), 2‐methyl furan and 3‐methyl‐3‐buten‐2‐one (especially during exposure to light, iron and high temperatures).     

Shelf‐life prediction of edible fats and oils using Rancimat

Determining the shelf‐life of edible fats and oils under normal storage conditions is a tedious and time‐consuming task. Accelerated tests are therefore frequently used to determine the stability of the products at ambient conditions. However, the mechanisms of lipid oxidation at accelerated conditions may be different from those under normal storage conditions, leading to errors in the shelf‐life predictions. This article describes an automated accelerated method, namely Rancimat, for shelf‐life prediction of edible fats and oils under normal storage conditions, and the effect of its operational parameters on these predictions.     

Assessment of resin adhesives aging by means of rheological parameters,Inverse Gas Chromatography,and FTIR

In this study, the rheological parameters as well as Flory–Huggins parameter determined by Inverse Gas Chromatography (IGC) were applied for assessment of the changes occurring during storage of the resole resin and their composites. It was proved that storage of resole and its composites at the low temperature (about 10°C) can slow significantly the process of their aging. Main idea of research was to determine time dependence of rheological properties for resole resin. These data should enable to extend shelf life of resin containing products. The rheological properties of samples were studied by the determination of flow curve. Share rate was changed from 10 to 500 1/s. Samples were examined in following intervals (increasing storage time): immediately after preparing the sample and then after storage, respectively: after two, four, eight, and twelve weeks. To extend shelf life of resin, it was mixed with different additives: zeolite Micro 20, Mg(OH)₂, PAF, synthetic zeolites: sodium form Z1, hydrogen form Z2. Flory–Huggins parameter determined by use of IGC let to assess physicochemical changes occurring in resole and its composites during storage. IGC turned out to be more sensitive method for assessment of changes occurring during resin aging than rheological measurements. FTIR technique was used to assess chemical changes occurring during resoles compositions storage. It indicated that oxidation reaction can occur during resoles composite aging.     

The use of electronic and human nose for monitoring rapeseed oil autoxidation

This work was aimed at assessing the effectiveness of the electronic nose to monitor off‐flavor associated with lipid oxidation as a supplementary tool to human sensory panel assessment. Therefore, correlations between electronic nose and sensory analysis were determined. Also GC analyses and chemical analyses of oil samples were run to characterize the analyzed samples with well‐described parameters. Refined rapeseed oil was subjected to an accelerated storage test for 12 days at 60 °C and to an ambient temperature storage test in which it was stored in retail plastic bottles for up to 6 months. PCA of electronic nose data samples stored at an elevated temperature was related to PCA of sensory analysis, and similarities in sample clustering were observed. For samples stored at room temperature, the human panel showed greater sensitivity than the electronic nose. Prediction models based on PLS of electronic nose data were able to predict the sensory quality changes during storage at elevated and room temperature, ranging from 0.721 to 0.989 and from 0.849 to 0.881 (p <0.05), respectively. PV and p‐AV were well predicted on the basis of both electronic nose (0.989, 0.998 for elevated temperature; 0.907, 0.881 for room temperature) and sensory analysis data (0.973, 0.993 for elevated temperature; 0.939, 0.886 for room temperature). Applicability of the electronic nose technology to verify sensory and rancidity changes during storage showed to be promising in quality control of oils.     

Oxidations involving the heme complex in raw meat

In raw meat systems one is concerned with both lipid and pigment oxidations. Heme pigments catalyze oxidation of tissue lipids causing a stale or rancid odor and flavor. Free radicals from lipid oxidation can oxidize and decompose the red ferrous hemes. This results in the brown colored meat commonly rejected by the consumer. This paper reports three approaches taken to study means of reducing these nonmicrobial oxidative changes: (1) enzymatic reduction of metmyoglobin to maintain ferrous pigments; (2) inhibition of lipid and pigment oxidation and decomposition by means of an antioxidant and reducing agent; (3) the use of model systems to study the kinetics of lipid and heme oxidations. While a biological metmyoglobin reducing system has been found to exist in post mortem suscles, its practical significance in relation to retention of meat color and odor is not fully understood. Anaerobic conditions are usually necessary to achieve complete reduction. The common phenolic antioxidants, butylated hydroxyanisole (BHA) and propyl gallate, along with ascorbic acid will protect meat color and odor for up to eight days according to both chemical analyses and sensory evaluations. Such meat can be packaged aerobically. Surface pigments will remain as the bright red oxymyoglobin familiar to the consumer rather than the purple reduced myoglobin of anaerobically packaged meat. The peroxide-heme ratio may be an important factor in determining rate of oxidation of both pigment and lipid. Maintenance of a high proportion of heme to lipid appears to prevent catalysis of lipid oxidation. The importance of this in relation to actual storage life of meat has not been explored. One of 28 papers presented at the Symposium, “Metal-Catalyzed Lipid Oxidation,” ISF-AOCS World Congress, Chicago, September 1970.     

Rancidity development during frozen storage of mackerel (Scomber scombrus): effect of catching season and commercial presentation

Hydrolytic and oxidative rancidity development and its effect on quality loss were studied in frozen mackerel (Scomber scombrus) by biochemical and sensory indices. The effect of the lipid content on fish damage at a commercial freezer temperature (?20 °C) was studied for up to 12 months; thus, mackerel caught at two different times of the year (May and November) was checked, May being the period of minimum lipid content, while November is known to be the time of maximum lipid content. The study was also focused on two different kinds of fish products (whole fish and fillets). Increasing lipid hydrolysis was observed for all kinds of samples during the frozen storage; no differences (p >0.05) between whole fish and fillets were found for free fatty acid formation; however, mackerel from May showed a higher (p <0.05) hydrolysis development than its counterpart from November. Increasing lipid oxidation (peroxide value and thiobarbituric acid index) was observed for all kinds of samples during the frozen storage. Fillet lipid oxidation was found to be higher (p <0.05) than in whole fish. Fattier mackerel (November fish) showed a higher (p <0.05) oxidation development than its counterpart from May in the case of fillet products. Results of fluorescence assessment, related to interaction compound formation, proved to be higher (p <0.05) in fillets than in whole fish, although they were higher (p <0.05) in May samples. Sensory analysis corroborated the biochemical analyses, so that fillets showed a shorter shelf life (1 and 3 months for November and May fish, respectively) than their whole fish counterparts (5 months for November and May mackerel).     

Fatty acid composition of wild and farmed Atlantic salmon (<Emphasis Type="Italic">Salmo salar</Emphasis>) and rainbow trout (<Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis>)

The goal of this study was to examine the FA composition of wild and farmed Atlantic salmon (AS) and rainbow trout (RT). FA profiles were obtained by GC/FID. Results showed that lipid and n−3 highly unsaturated FA contents of farmed and wild AS were similar. Total n−3 and n−6 PUFA were significantly higher in farmed AS than in wild AS. Farmed RT contained more fat and less n−3 PUFA than wild RT. Our results show that farmed salmonids provide high levels of n−3 HUFA to consumers.     

Identification of some rancidity measures at the end of the shelf life of sunflower oil

Sunflower oil was stored at 40 °C, and changes in peroxide value (PV), anisidine value (AnV), thiobarbituric acid (TBA) value, iodine value (IV), conjugated dienes (CD) and hexanal (Hex) levels were monitored. Changes in the odor of samples during storage were assessed sensorially. Apart from IV, which decreased as storage progressed, the other chemical rancidity measures increased. Sensory shelf life data were adequately described by the Weibull distribution, with the 95% confidence interval of the nominal shelf life of sunflower oil, at 40 °C, being 9.04–10.45 wk. The chemical rancidity measures at the end of the sensory shelf life were: PV of 338–352.8 meq peroxide/kg, CD of 1.20–1.24% conjugated dienoic acid, AnV of 21.45–45, TBA values of 23.4–37, and Hex content of 4.79 mg/kg, while IV exhibited a decrease of 8.5–10%. The chemical measures of rancidity marking the end of the sensory shelf life provide objective indices for monitoring the shelf life of sunflower oil.     

Postharvest Ozone Treatment of Cucumber as a Method for Prolonging the Suitability of the Fruit for Processing

Ground cucumber, as a nutrient, is a product highly valued by consumers in both fresh and processed form. The aim of the research was to develop a technology for extending the shelf life of ground cucumbers stored at room temperature before further processing. For this purpose, ozone treatment was utilized and the changes in the mesocarp and the peel puncture strength of the ozonated and the control cucumbers during storage were measured. Ozonation extended the shelf life of ground cucumber fruit making them useful for longer time for further processing.     

Microencapsulation of fish oil

Fish oil is susceptible to oxidative degradation generating undesired lipid peroxides, secondary and tertiary oxidation products. These products pose health risks, reduce shelf‐life stability and cause fishy odor and taste leading to decreased sensory quality. Microencapsulation of fish oil using spray drying, coacervation, ultrasonication and membrane emulsification techniques is employed to overcome these problems.