Modelling quality changes in Songpu mirror carp (Cyprinus carpio) fillets stored at chilled temperatures: comparison between Arrhenius model and log‐logistic model

To understand the quality changes in Songpu mirror carp (Cyprinus carpio) fillets during chilled storage, sensory score, total aerobic counts (TAC), total volatile basic nitrogen (TVB‐N) and electrical conductivity (EC) of the fillets stored at 270, 273, 276, 282 and 288 K were investigated. Furthermore, both Arrhenius model and log‐logistic model were established to predict the quality changes. The high regression coefficients (R² > 0.90) represented the acceptability of both Arrhenius model and log‐logistic model. Relative errors between predicted values and observed values were all within ±5% for models based on EC, within ± 25% for models based on TAC and TVB‐N (except the TVB‐N value on 9th and 15th day). The relative errors of sensory score were all within ±35% in the first 9 days. It is concluded that both Arrhenius model and log‐logistic model based on EC, TAC or TVB‐N can be applied in modelling quality changes in Songpu mirror carp fillets during storage within 270–288 K.     

Combined effect of freeze chilling and MAP on quality parameters of raw chicken fillets

The effect of short-term frozen storage prior to thawing on the quality of freeze-chilled chicken fillets was investigated, as was the effect of modified atmosphere packaging (MAP). Four process treatments were used: (1) fresh chicken chilled at 4 degrees C without previous freezing, (2) freeze-chilled for 7 days and thawed at 4 degrees C, (3) chilled at 4 degrees C packaged under MAP (70% N(2)-30%CO(2)), and (4) packaged under MAP, freeze-chilled for 7 days and thawed at 4 degrees C. Microbiological, chemical and sensory analyses were conducted on samples for a period up to 15 days. Freeze-chilled fillets gave a lower total viable count (TVC) at a given sampling day than chilled fillets. MAP, as expected, delayed microbial growth. The Pseudomonads were the dominant microbial species in fillets under aerobic conditions. MAP reduced the populations of Pseudomonads by 2-4 log cfu/g. Lactic acid bacteria (LAB) and Enterobacteriaceae increased progressively for all treatments throughout storage. Yeasts and molds were inhibited by MAP and by freeze chilling. Total volatile basic nitrogen (TVB-N) values increased rapidly for the chilled fillets but remained significantly lower for the freeze-chilled and the MA-packaged samples. MAP and especially freeze chilling enhanced drip loss. MAP did not affect redness or yellowness of product while freeze chilling decreased product redness. Lightness was not affected by either MAP or freeze chilling. Based on taste, which proved to be the most sensitive sensory attribute, shelf life of product ranged from 6 to 7 days for all treatments leading to the conclusion that freeze chilling is a suitable technology for fresh chicken fillets enabling their distribution as a frozen product and upon subsequent thawing at their final destination, their retail display as chilled products. MAP in combination with freeze chilling had a negligible effect on product quality.     

Changes in biogenic amines of silver carp (Hypophthalmichthys molitrix) fillets stored at different temperatures and their relation to total volatile base nitrogen,microbiological and sensory score

BACKGROUND: Biogenic amines have received considerable attention owing to their undesirable effects in humans. There are few studies of changes in biogenic amine contents related to freshwater fish. Silver carp is an important freshwater fish species in China. This study aimed to investigate the changes in biogenic amines and their relation to total volatile base nitrogen (TVB‐N), microbiological and sensory score of silver carp fillets stored at 0, 3 and 15 °C. RESULTS: The total biogenic amine contents of all silver carp fillets (regardless of storage time and temperature) ranged from 13.05 to 318.10 mg kg^?1. Putrescine and histamine were the main biogenic amines in silver carp fillets during storage. Cadaverine was only detected after 12 days at 3 °C and after 2 days at 15 °C. Spermidine and spermine contents increased during the early storage period and then slightly decreased. CONCLUSION: Low temperature could control the quality of silver carp fillets by inhibiting the contents of biogenic amines. Putrescine showed significant correlation with TVB‐N, total aerobic content, sensory score, tryptamine and phenylethylamine. Putrescine was a good quality marker of silver carp fillets in the cold chain. Copyright © 2012 Society of Chemical Industry     

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.     

Compositional and chill storage characteristics of microwave‐blanched sutchi catfish (Pangasianodon hypophthalmus) fillets

The effect of microwave blanching on quality characteristics of vacuum and conventional polyethylene‐packed sutchi catfish fillets was evaluated under chilled condition. Emphasis has been given to retain the sensory characteristics such as colour and textural properties, which is a major problem in sutchi catfish fillets during extended chill storage. In general, microwave blanching imposed minimum changes on fatty acid and mineral composition of fish meat. A marginal increase in fat content was recorded after microwave heating of fish fillets. The microwave‐blanched fillets showed minimum cooking loss of 3.2 mL per 100 g meat. A slower increase in spoilage parameters was obtained with microwave‐blanched samples compared with unblanched samples, demonstrating the higher storage stability of the sample under chilled conditions. Microwave heating of fish fillets coupled with quick‐chilling and packing under vacuum improved the colour and texture stability of sutchi catfish fillets to a considerable extent. Microwave blanching increased the hardness and chewiness values and decreased the stiffness values of fish fillets. The biochemical and sensory evaluation of microwave‐blanched and vacuum‐packed sutchi catfish fillets showed extended storage life of 21 days, compared with 12 days for unblanched vacuum‐packed samples.     

The impact of collagen on softening of grass carp (Ctenopharyngodon idella) fillets stored under superchilled and ice storage

The objective of this work was to study the impact of collagen on softening of grass carp (Ctenopharyngodon idella) fillets during chilled storage. The fillets were stored under superchilling (?1.5 ± 0.2 °C) and with ice (0.2 ± 0.1 °C) for 21 days, and texture properties, collagen and the related enzyme activities were measured. Results showed that firmness and collagen content were strongly influenced by storage temperature and time. Fillet firmness decreased by 32.3% (superchilling) and 49.6% (ice stored) of the initial values after 3 days of storage, respectively. Total collagen content decreased with time, but different collagen fractions showed variations. Collagen degraded to different extents depending on storage conditions as indicated by SDS‐PAGE and amino acid analysis. In addition, collagenase activity declined significantly during the first 3 days, followed by a slow increase. This study demonstrated that collagen degradation was involved in grass carp fillet softening and provided useful information for fillet quality improvement.     

Quality changes and microbiological spoilage analysis of air‐packed and vacuum‐packed silver carp (Hypophthalmichthys molitrix) fillets during chilled storage

The effects of air‐packed (AP) and vacuum‐packed (VP) on quality and microbial characteristics of silver carp (Hypophthalmichthys molitrix) fillets during chilled storage (4 ± 1 °C) were investigated. The fillets were analyzed for sensory scores, total volatile basic nitrogen (TVB‐N), ATP‐related compounds (ATP, IMP, HxR, and Hx), K value, and biogenic amines (BAs). The results proved that VP inhibited the increase of microorganisms, TVB‐N, Hx, and putrescine in silver carp, and slowed the reduction in sensory score. Therefore, VP can be applied for preservation of the silver carp fillets to improve its quality. For identification, 16S rRNA genes of the isolated pure strains were sequenced and analyzed. On the initial day of storage, Chryseobacterium was the dominant bacterial genus. At the end of shelf life, Pseudomonas was the most common group in AP fillets and Aeromonas followed by Yersinia were found mainly in VP samples.

Practical applications

Silver carp (Hypophthalmichthys molitrix) are distributed widely in fresh water systems. The world aquaculture production of silver carp was 4,354,638 tons, and it ranked second highest among freshwater fish species in 2015, but they are perishable during storage because of microbial spoilage and biochemical reactions. Vacuum packaging (VP) has proved to be effective for extending the shelf‐life of aquatic products by excluding oxygen that prevents the growth of spoilage bacterial. However, little information is available on the microbial succession of VP silver carp. Therefore, this work was to determine the differences of microbiological succession on chilled silver carp fillets under air‐packed (AP) and VP conditions using a combination of culture‐based and 16S rRNA gene analysis methods. Furthermore, this study will give valuable information about development and spoilage of VP silver carp fillets.     

Establishment of quality predictive models for bighead carp (Aristichthys nobilis) fillets during storage at different temperatures

Quality predictive models were developed to predict the freshness of bighead carp (Aristichthys nobilis) fillets during storage at different temperatures. Quality indices [sensory score, total volatile base nitrogen (TVB‐N), total aerobic counts (TAC) and K value] at ?3, 0, 3, 9 and 15 °C were estimated and kinetically modelled by the Arrhenius equation. The activation energy (E_A) of sensory score, TVB‐N, TAC and K value was 78.17, 75.93, 106.53 and 76.21 kJ mol^?1, and the corresponding rate constants (k₀) were 1.16 × 10¹⁵, 2.60 × 10¹⁴, 4.05 × 10¹⁹ and 1.36 × 10¹⁵. The high regression coefficients (R² > 0.87) indicated the acceptability of the zero‐order reaction for sensory score, TVB‐N, TAC and K value. Relative errors between predicted and observed freshness indicators values of sensory score, TVB‐N, TAC and K value were all below 10% except the values at 6th day of K value, 3rd day and 9th day of TVB‐N. These results indicated that the models based on sensory score, TVB‐N, TAC and K value could effectively predict the freshness indicators of bighead carp fillets at the range of ?3 to 15 °C.     

The effects of thyme (Thymus vulgaris L.) oil concentration on liquid-smoked vacuum-packed rainbow trout (Oncorhynchus mykiss Walbaum, 1792) fillets during chilled storage

This study examined the effects of thyme oil on chemical properties, microbiological changes, and sensory quality in vacuum-packed liquid-smoked rainbow trout fillets under chilled storage. After 150 days of storage, the total volatile basic nitrogen (TVB-N) values were 30.52, 27.5 and 39.43 mg/100 g, and total viable counts (TVC) were 5.34, 4.96 and 5.53, for thyme oil additions of 10 (T10), 50 (T50) and 0 (control; T0) mL/L brine, respectively. The highest acceptable TVB-N value was adopted as 30 mg /100 g, corresponding to shelf lives of 135, 150, and 105 days for T10, T50, and T0, respectively. T50 addition of thyme oil to liquid-smoked rainbow fillets extended shelf life T10 and T50, gave acceptable sensory quality and limited microbiological growth during chilled storage.     

Biochemical and physicochemical changes in catfish (Silurus glanis Linne) muscle as influenced by different freeze–thaw cycles

Freeze–thaw cycles affected the biochemical and physicochemical properties of catfish fillets. When the number of freeze–thaw cycles increased, the activities of α-glucosidase and β-N-acetyl-glucosaminidase increased (P<0.05). No increase in non-heme iron content was observed (P>0.05); however the heme iron content decreased (P<0.05). This suggested that the freeze–thaw process caused damage of the cell and hemeprotein, resulting in the release of pro-oxidants. No differences in metmyoglobin and autolysis products (P>0.05) were found as affected by freeze–thaw cycles. After 3 days of chilled storage (2–4°C), a small non-significant increase in non-heme iron content was observed with a concomitant decrease in heme iron. Thiobarbituric acid-release substance increased significantly (P<0.05), especially for the fillets subjected to five freeze–thaw cycles. Components with spectral characteristics similar to hydrogen peroxide-activated hemoproteins were detected with a concomitant decrease in metmyoglobin content in five-cycle freeze–thawed samples after 3 days of storage. The freeze–thaw process therefore has a detrimental effect on the quality of catfish fillets, particularly after chilled storage.     

Evaluation of Shelf Life of Superchilled Cod (Gadus morhua) Fillets and the Influence of Temperature Fluctuations During Storage on Microbial and Chemical Quality Indicators

Quality changes of aerobically packed cod fillets stored under superchilling and abusive temperature conditions were characterized by the growth of specific spoilage organisms (SSO) and the production of microbial metabolites measured by an electronic nose along with traditional sensory and chemical analysis (total volatile basic nitrogen [TVB‐N], pH). A new process based on quick contact freezing and cold air blasting was used to achieve superchilling of fillets before chilled (0.5 °C) or superchilled (‐1.5 °C) storage. Photobacterium phosphoreum dominated under temperature abusive conditions coinciding with high levels of TVB‐N and increased electronic nose responses indicating increased levels of alcohols and aldehydes at sensory rejection. Dominating growth of Pseudomonas spp. in 1 batch was associated with the origin, the catching method, and the cooling conditions during processing. The superchilling process followed by superchilled storage (‐1.5 °C) extended the sensory shelf life of the fillets for at least 3 d compared with traditional process, resulting in a total shelf life of 15 d. High content of TVB‐N was observed in superchilled fillets at sensory rejection. P. phosphoreum counts were lower under superchilling conditions (6.0 to 6.8 log colony‐forming units [CFU]/g), compared with the traditionally processed chilled fillets (7.2 log CFU/g). However, H₂S‐producing bacteria appeared to grow steadily under superchilling conditions reaching counts as high as 7.6 log CFU/g at sensory rejection.     

Physicochemical Responses and Quality Changes of Turbot (Psetta maxima) During Refrigerated Storage

The sensory, physicochemical, microbiological, and volatiles changes of postmortem turbot during 20 days of chilled storage at 4°C were studied. No significant changes were found in pH value and whiteness during the storage, while total viable counts, total volatile base nitrogen, and K-values increased significantly with storage time. The textures profile, springiness and resilience, and sensory attributes changed significantly during storage. A total of 50 volatile compounds including aldehydes, ketones, esters, alcohols, alkenes, alkanes, aromatics, amines, and others were identified in turbot muscle during storage by the solid-phase microextraction and gas chromatography–mass spectrometry methods. Among these volatile components, the relative content of some decreased significantly with time, while others increased significantly. The results suggested that hardness, springiness, resilience, sensory attributes, total volatile base nitrogen, K-value, and total viable counts combined with some volatile compounds could more perfectly reflect the quality changes of turbot during storage. The study indicated that turbot fillets stored at 4°C maintain better quality for 16 days during storage.     

壳聚糖对冷藏鲤鱼片品质变化的影响

为了解壳聚糖处理对4 ℃冷藏条件下鲤鱼片品质的影响,测定对照组、T1组（20 g/L壳聚糖＋体积分数0.5%醋酸）、T2组（体积分数0.5%醋酸）鲤鱼片4 ℃冷藏条件下感官分值、菌落总数（total aerobic counts,TAC）、挥发性盐基氮（total volatile basic nitrogen,TVB-N）含量、pH值和生物胺含量等指标的变化,分析壳聚糖对冷藏鲤鱼片品质的影响。结果表明：3 组鲤鱼片的感官分值随着贮藏时间的延长逐渐降低,对照组鲤鱼片在贮藏8 d后感官不可接受,T1组鲤鱼片的总体感官分值高于T2组;3 组鲤鱼片的TVB-N含量在贮藏期间呈增长趋势,贮藏10 d时,对照组鲤鱼片的TVB-N含量与T1、T2组差异显著（P＜0.05）,对照组鲤鱼片贮藏10 d时的TVB-N含量达31.37 mg/100 g,而T1组仅为13.07 mg/100 g;T1组鲤鱼片TAC的增长速率显著低于对照组和T2组（P＜0.05）;腐胺、尸胺的含量随着贮藏时间的延长而升高,贮藏后期,T1、T2组鲤鱼片的腐胺含量显著低于对照组（P＜0.05）。壳聚糖的加入可以改善冷藏鲤鱼片的品质,并可将货架期延长2 d。     

Nondestructive determination of salmon fillet freshness during storage at different temperatures by electronic nose system combined with radial basis function neural networks

This study develops a predictive model for determining freshness of salmon fillets during cold storage at different temperatures using electronic nose combined with principal component analysis (PCA) and radial basis function neural networks (RBFNNs). The electronic nose sensed ammonia/amines, hydrocarbons, solvents and aromatics that increased during storage. The concentrations of the volatiles were compared with the increased thiobarbituric acid (TBA), total volatile basic nitrogen (TVB-N), total aerobic bacteria count (TAC) and decreased of sensory assessments (SA). Gas chromatograph–ion mobility spectrometry analysis confirmed the changes in gas species. RBFNNs and PCA were used to establish predictive models and the relative errors of TBA, TVB-N and TAC by the PCA-RBFNNs model were all within ±10% and SA was within ±15%. These results suggest that the PCA-RBFNNs model can be used to predict changes in the freshness of salmon fillets stored at −2 to 10 °C.     

Effect of sub‐freezing storage (−6, −9 and −12 °C) on quality and shelf life of beef

Based on the results of low field nuclear magnetic resonance (LF‐NMR) in our current study (the frozen state of ?6, ?9 and ?12 °C were nearly the same with extremely low free water content), ?6, ?9 and ?12 °C was designated as sub‐freezing temperatures. The effects of sub‐freezing storage compared with conventional chilling (4 °C), superchilling (?1 °C) and conventional freezing (?18 °C) on the quality and shelf life of beef were analysed. Results showed that the shelf life of beef is extended to 84 and 126 day at ?6 °C and ?9 °C, respectively. However, the TVB‐N values of the samples stored at ?12 °C and ?18 °C remained below 15 mg/100 g even on 168 day. Furthermore, shear force, colour, pH, thiobarbituric acid reactive substances (TBARS) and sensory properties were also measured. Consequently, the sub‐freezing storage has significantly extended the shelf life of beef compared to chilling and superchilling (P < 0.05). Moreover, no significant difference (P > 0.05) was found between the indicators for quality and shelf life of samples stored at ?12 and ?18 °C throughout 168 days.     

Superchilled,chilled and frozen storage of Atlantic mackerel (Scomber scombrus) – effect on lipids and low molecular weight metabolites

Quality changes in Atlantic mackerel fillets during superchilled, chilled and frozen storage focusing on lipid quality, colour and changes in low molecular weight metabolites relevant for quality and safety were studied. Low formation of oxidation products was observed in chilled (up to 7 days), superchilled (up to 14 days) and frozen storage (up to one year). Only slight formation of TBARS was measured in the samples which correlated with the increasing fillet yellowness. The profile of low molecular weight compounds, analysed by high-resolution NMR, showed clear grouping of the different samples according to both treatment and storage time. The increase in K-value was highest in the chilled samples, reaching a K-value of 93 ± 3% on day 5, exceeding the proposed limit of human consumption (80%) while superchilling reached a K-value of ca 90 % after 14 days. Frozen samples showed acceptable quality in the whole storage period.     

白鲢鱼片在冷藏和微冻条件下的鲜度和品质变化

以白鲢鱼为实验对象,通过测定菌落总数、挥发性盐基氮（total volatile basic nitrogen,TVB-N）值、pH值、K值、三甲胺（trimethylamine,TMA）值、2-硫代巴比妥酸（2-thiobarbituric acid,TBA）值等鲜度指标,结合感官评价,以期探究冷藏以及微冻条件下鲢鱼片的品质变化规律。结果表明,在4 ℃冷藏和－2 ℃微冻条件下贮藏的鲢鱼片TVB-N值、TMA值、菌落总数值均随贮藏时间的延长而呈增长趋势;pH值先降低后增高;感官分数值呈降低趋势。综合各项指标变化,4 ℃冷藏条件下鲢鱼片的货架期为6 d,－2 ℃微冻条件下货架期为18 d,与冷藏相比,微冻能明显延长白鲢鱼片的货架期。     

Functional stability of gelatin–lignosulphonate films and their feasibility to preserve sardine fillets during chilled storage in combination with high pressure treatment

The physico-chemical and functional stability of gelatin (G) and gelatin–lignosulphonate (GLS) films stored during 4 weeks at 21 °C, (i) in container or (ii) in contact with oil, was examined. Addition of lignosulphonate dramatically increased ABTS radical scavenging and ferric ion reducing capacities, which remained practically unaltered after the storage period. GLS films exhibited reduced elongation at break, irrespective of storage medium, and retained their water resistance. The feasibility of using GLS film to improve the quality of sardine fillets during chilled storage, alone or in combination with high pressure treatment (300 MPa/10 min/7 °C), was evaluated. The combined use of GLS film with high pressure reduced microbial growth, total volatile basic compounds (TVB) and thiobarbituric acid reactive substances (TBARS) during chilled storage. No noteworthy high pressure-induced colour changes were observed in the sardine muscle using this treatment alone, although an increase in yellowness due to the combined treatment was detected.Industrial RelevanceAddition of lignosulphonate dramatically increased antioxidant properties (ABTS radical scavenging and ferric ion reducing) of gelatin films, which remained practically unaltered during 4 weeks of storage at room temperature. Application of those films confers stability during storage of chilled sardine, especially in combination with high pressure treatment. These novel packaging was promising for fish preservation.     

The combined effect of superchilling and modified atmosphere packaging using CO2 emitter on quality during chilled storage of pre‐rigor salmon fillets (Salmo salar)

BACKGROUND: Pre‐rigor fillets of Atlantic salmon were either superchilled or chilled prior to packaging in air or in modified atmosphere (MAP, 60% CO₂/40% N₂) with a CO₂ emitter, in 5.3 L high‐density polyethylene trays with three to four layers of fillets (3.0–3.7 kg). All samples were stored at 0.1 °C for 28 days. RESULTS: Fillets stored in MAP had significantly lower bacterial growth compared to fillets stored in air, and MAP superchilled bottom fillets had lower bacterial counts compared to the corresponding chilled fillets. Samples superchilled prior to refrigerated storage in air had similar bacterial growth to ordinary chilled samples. Faster fillet softening during storage and higher liquid loss were observed in superchilled MAP samples. CONCLUSION: Combining short‐term superchilling and MAP with a CO₂ emitter prolonged the shelf‐life of pre‐rigor salmon fillets, which can improve sustainability throughout the value chain. The superchilling method needs to be optimized to avoid negative effects on texture and liquid loss. Copyright © 2009 Society of Chemical Industry