Chemical and microbial analyses of squid muscle (Loligo plei) during storage in ice

Chemical and microbial changes in squid muscle (Loligo plei) and the efficiency of chemical indices for freshness evaluation were investigated during storage in contact ice (CI) and non-contact ice (NC). Psychrotrophic bacterial counts and non-protein nitrogen, free amino acids, trimethylamine, volatile basic nitrogen (VBN), urea and free tryptophan contents were periodically determined in squid muscle. No difference (P < 0.05) was detected between treatments regarding the increase of psychrotrophic bacterial counts in squid muscle during storage. The leaching of soluble compounds in CI treatment drastically affected the efficiency of the chemical indices for freshness. Trimethylamine and VBN contents in squid muscle increased only after day 9 and no increase was observed in free tryptophan and urea contents in CI treatment. In the NC treatment the contents of VBN and trimethylamine slowly increased during the first days of storage whereas free tryptophan and urea contents markedly increased during the whole storage. Free tryptophan and urea can be useful freshness indices for L. plei in storage conditions wherein leaching have been minimized.     

Skin Color Changes of Squids Todarodes pacificus and Loligo bleekeri During Chilled Storage

ABSTRACT: Squid skin color is one of many important factors to evaluate market values. The effects of chilling and hypoxia treatments on skin color of Japanese common squid Todarodes pacificus and spear squid Loligo bleekeri were investigated to prevent highly fresh squids from abnormal fading skin color with inappropriate commercial value losses. Skin color of the squids gradually faded away during ice-cold storage. Measurements of chromato-phores expansion showed that skin color can be maintained well after death by keeping the bodies well-oxygenated and avoiding direct contact with ice.     

The effect of preliminary processing and period of storage on the quality of frozen Boletus edulis (Bull: Fr.) mushrooms

This paper investigates the effect on the quality of frozen Boletus edulis (Bull: Fr.) mushrooms of blanching or soaking and blanching in aqueous solutions containing combinations of added substances safe for human consumption, or period of frozen storage. During 12 months of storage, sensory evaluations, instrumental colour measurements and chemical analyses of the frozen products were carried out every four months. Based on the results of the sensory evaluation, a maximum storage period of four months was set for the frozen product obtained from unblanched mushrooms. Frozen products having undergone preliminary processing retained good sensory quality for up to 12 months. Soaking, blanching and freezing resulted in the appearance of colours, such as yellow, honey and pink–violet. As a result of freezing, decreases in the contents of thiamine, riboflavin and vitamin C were noted. Blanching in water, as a method of pre-processing, was sufficient for maintaining acceptable sensory quality.     

Pink discoloration and quality changes of squid (Loligo formosana) during iced storage

Pink discoloration and quality changes of squid (6-10 squids/kg) with and without deskinning during iced storage at different squid/ice ratios (1:1 and 1:2, w/w) for 16 days were investigated. The increases in a* and b*-values of squid mantle were observed with increasing storage time (p < 0.05), indicating the formation of pink color on the mantle. The increase was more pronounced in squid without deskinning with a squid/ice ratio of 1:1 (p < 0.05). No changes in a*-value were observed in deskinned squid throughout the storage, regardless of squid/ice ratio (p > 0.05). However, the slight increase in b*-value was found in the squid with deskinning during the storage. Psychrophilic bacteria counts of squid increased continuously as the storage time increased. Coincidental increases in total volatile base (TVB), trimethylamine (TMA) and ammonia contents were observed during the storage. The rates of increase were greater in the samples with a squid/ice ratio of 1:1 than those found in the samples kept in ice with a squid/ice ratio of 1:2. Pink discoloration, psychrophilic bacteria count, TVB and TMA contents were much lowered when the squid without deskinning was treated with 0.1 g/100 mL sodium azide (NaN₃) prior to storage, suggesting that microbial growth was associated with those changes. Therefore, deskinning together with icing using a sufficient amount of ice as well as the use of safe antimicrobial agent could be a means to lower the pink discoloration and retard the losses in quality of squid stored in ice.     

Physicochemical and functional changes in jumbo squid (Dosidicus gigas) mantle muscle during ice storage

Physicochemical and functional changes of jumbo squid (Dosidicus gigas) mantle muscle stored in ice for 15 days were evaluated. Proximate analysis, pH, protein solubility (PS) and SDS-PAGE profile changes were monitored for muscle proteins, while texture profile analysis (TPA) (gel strength, elasticity and cohesiveness), water holding capacity (WHC) and colour changes were monitored for gels produced from this muscle. Fresh muscle chemical composition varied according to fishing season and/or physiological status presented by specimens. pH and PS were stable (p ? 0.05) throughout the study with a slight tendency to decrease towards the end of study. SDS-PAGE revealed no drastic changes in proteins influencing gelation (i.e., myosin). TPA and WHC of gels decreased towards the end of experiment; however, due to sampling variability, no significant differences (p ? 0.05) were found over storage time. Changes in gel colour were observed with hue angle decreasing towards yellow hues. Improved post-capture management of mantle muscle preserved its integrity and functionality for up to two weeks.     

Wine industry residues extracts as natural antioxidants in raw and cooked chicken meat during frozen storage

The effect of Isabel (IGE) and Niagara (NGE) grape seed and peel extracts on lipid oxidation, instrumental colour, pH and sensory properties of raw and cooked processed chicken meat stored at -18°C for nine months was evaluated. The pH of raw and cooked samples was not affected by the addition of grape extracts. IGE and NGE were effective in inhibiting the lipid oxidation of raw and cooked chicken meat, with results comparable to synthetic antioxidants. The extracts caused alterations in colour, as evidenced by the instrumental (darkening and lower intensity of red and yellow colour) and sensory results of cooked samples. In the sensory evaluation of odour and flavour, IGE produced satisfactory results, which did not differ from synthetic antioxidants. These findings suggest that the IGE and NGE are effective in retarding lipid oxidation of raw and cooked chicken meat during frozen storage.     

Control of salmon oil photo-oxidation during storage in HPMC packaging film: Influence of film colour

The efforts are being made to design protective hydroxypropyl methylcellulose (HPMC) colour packages to avoid photo-oxidation of edible fats and oils. In the present study, edible films of HPMC containing different edible colours like blue, green, yellow, red and white were tested for their ability to avoid photo-oxidation in salmon oil. The samples taken in petri-dishes and covered with coloured HPMC films of thickness 40 μm were placed under fluorescent light at 20 °C. During storage, chemical parameter of oil quality such as fat oxidation was monitored during 8 days of storage. Oxygen consumption by gas chromatography, conjugated diene values by spectrophotometery and fatty acid composition by gas chromatography (GC) was measured. The results of our study show that HPMC films with suitable edible colours act as adequate light barrier to avoid photo-oxidation of salmon oil during extended storage. HPMC films containing white, red and yellow edible colours show good control of oil photo-oxidation almost similar to the control samples stored in darkness. Oil samples treated with blue and green edible films show gradual increase in oil oxidation with increasing time of light exposure. Oxidation behaviour of samples treated with blue and green films was almost similar to the samples stored in transparent films.     

Influence of dietary creatine monohydrate and carcass cooling rate on colour characteristics of pork loin from different pure breeds

Increased creatine content in the muscle may delay postmortem (pm) lactate formation and postpone pH decline, hence potentially affect the colour of pork. The influence of dietary supplementation with 0 or 50 g creatine monohydrate (CMH)/d for 5 days prior to slaughter and two cooling rates of pig carcasses on the colour characteristics of pork loin from purebred Duroc and Landrace pigs was investigated. CMH increased the content of creatine phosphate in pork loin measured immediately following bleeding, delayed early pm pH decline and gave rise to less red and yellow colour, probably due to induction of a more pronounced oxidative muscle metabolism. A faster cooling rate pm induced darker and less yellow colour in loins from Duroc and Landrace pigs, while only loins from Landrace became less red. Loins from Duroc pigs were darker, less red and less yellow than loins from Landrace pigs, due to slower pH decline and a higher ultimate pH in these loins. Colour stability of pork loin during chill storage, measured as oxidation to metmyoglobin, was not affected by dietary CMH, cooling rate or pig breed. Consequently, the registered differences in colour between treatments during storage were merely due to the degree of initial blooming, and more attention to factors of importance for the degree of blooming should be in focus in future studies of factors of importance for meat colour.     

低温贮藏和解冻过程对鱿鱼品质的影响研究进展

鱿鱼是我国重要的远洋渔业捕捞对象,捕捞后需要及时进行船上冻结,因此,冷冻鱿鱼是各类鱿鱼制品生产的主要原料。低温贮藏尤其是冻藏是目前广泛应用的一种保鲜方法,冷冻水产品在加工前必须进行解冻,鱿鱼在低温贮藏和解冻过程中会发生汁液流失,影响其营养价值,导致品质劣变。冷冻水产品最终品质的好坏不仅取决于冷冻方法、冻藏温度、温度波动,还和后续的解冻方式有关。本文综述了鱿鱼在低温贮藏和解冻过程中发生的物理化学变化,主要从水分含量、蛋白质变性及氧化、脂质氧化、色泽、p H值和微生物组成及特定腐败菌等几个方面进行了阐述,旨在为水产加工企业在鱿鱼保鲜加工方面提供理论参考。     

Sensory colour assessment of fresh meat from pigs supplemented with iron and vitamin E

Pork muscle samples (M. longissimus dorsi) were obtained from pigs given one of four dietary treatments: (1) control diet; (2) supplemental iron [7-g iron (II) sulphate/kg feed]; (3) supplemental vitamin E (200-mg dl-α-tocopheryl acetate/kg of feed); and (4) supplemental vitamin E+supplemental iron. Muscle cores were packaged in polythene bags and placed in a retail refrigerated display cabinet at 5±1°C, under fluorescent light (1000 LUX) for up to 5 days. Samples were subjected to visual colour evaluation by a trained sensory panel (n=12) at 0, 1, 3 and 5 days. In addition instrumental L*, a* and b* values and drip loss were measured on each day of analysis. All samples became less red and browner over storage time in the refrigerated display cabinet. The vitamin E treated samples were more red and less brown compared with the other samples on successive days in the cabinet followed by the control, iron/vitamin E and iron treatments. The iron/vitamin E treatment was positioned midway between the vitamin E and iron treatments indicating that the vitamin E in the samples was effective in reducing the pro-oxidative effect of iron in inducing the brown metmyoglobin pigment development. Iron supplementation did not significantly (P<0.05) increase M. longissimus dorsi iron tissue levels, but had a detrimental effect on the visual sensory properties of the iron and iron/vitamin E treatment groups with greater metmyoglobin formation. Vitamin E appears to have promoted non-supplemental iron absorption in the vitamin E treated group without the detrimental sensory colour characteristics associated with ferrous sulphate supplementation. Drip loss increased in all samples during the course of the experiment with no significant (P<0.05) differences between the experimental groups. The panellists were able to differentiate the four experimental groups on each day of the study and were more effective in evaluating the colour quality of samples than instrumental assessment, i.e. the Hunter L* a* b* method.     

Jumbo squid (Dosidicus gigas) mantle muscle gelled-emulsified type product: formulation, processing and physicochemical characteristics

Jumbo squid ( Dosidicus gigas ), an abundant species in the Gulf of California, can have a great potential for production of gelled-emulsified type products. Thus, formulation, processing and physicochemical characteristics of frankfurter-type product from jumbo squid mantle muscle (JSF) was achieved. JSF were vacuum-packed and stored at 2–4 °C. Samples were analysed for physicochemical (colour, texture, TBARS, peroxide value, folding test, pH, and water content and holding capacity) and microbial changes at regular intervals during storage for up to 27 days. The sensory quality of the product was also evaluated. Shear force, cohesiveness and colour (hue angle and total colour difference) were the most affected ( P  <   0.05) parameters at day 27, changes most probably because of microbial growth as total aerobic counts increased to >2.7 × 10⁵ CFU g⁻¹ (day 21). Product showed acceptability. Results suggest a stable gelled-emulsified type product can be developed from jumbo squid mantle muscle opening a range of possibilities for product development.     

Application of high pressure processing for extending the shelf-life of sliced raw squid

This study was designed to evaluate the effect of high pressure processing (HPP) on the microbiological safety and quality of sliced raw squid during refrigerated storage. The sliced and vacuum-packed raw squid samples were treated at 200, 300, and 400 MPa for 20 min by using a custom-made high pressure processor. The numbers of psychrotrophic bacteria in the sliced raw squids treated at 200, 300, and 400 MPa were reduced by 0.5, 2.5, and >4.7 log CFU/g, respectively. The amounts of trimethylamine (TMA) produced in the sliced raw squids were reduced by 20, 33, and 51% at 200, 300, and 400 MPa, respectively, as compared to the control. The amount of total biogenic amines (BAs) in the control significantly increased up to 1.70 mg/g after 10 days of refrigerated storage, while that in the 400 MPa-treated squid sample gradually increased up to 1.33 mg/g. The autolytic activity values in the control, 200, 300, and 400 MPa-treated squid samples were 4.70, 2.28, 2.18, and 1.55 nkat/g, respectively, after 20 days of refrigerated storage. The HPP effectively retarded the microbial growth, TMA formation, autolytic activity in the sliced raw squids. Therefore, the HPP could be used as an effective processing tool for improving microbiological safety and quality of seafood.     

Evaluation of a slurry ice system for the commercialization of ray (Raja clavata): Effects on spoilage mechanisms directly affecting quality loss and shelf-life

The application of slurry ice, a biphasic system formed by small spherical ice crystals surrounded by seawater at sub-zero temperature, was evaluated as a new storage method for ray (Raja clavata), the elasmobranch fish species that exhibits highest commercial value in the European food markets. This advanced technique was used to compare with a control batch stored 10 days in flake ice. The results obtained in the sensory analysis indicated a significant extension of the overall quality (A class fish) from 3 days (flake ice) to 6 days (slurry ice). The development of ammonia external odour was the limiting parameter in both batches and was correlated with the activity of the endogenous mechanisms involved in the degradation of proteins and non-protein-nitrogen (NPN) rather than with the activity of proteolytic microorganisms. Storage of ray in slurry ice significantly (P<0.05) slowed down both biochemical (as estimated by the follow-up of the pH, TVB-N and K-value evolution) and microbial degradation mechanisms (estimated by the development of psychrotrophes and mesophiles counts) in chilled ray muscle. According to the parameters evaluated, storage of ray in slurry ice extends the shelf-life of this elasmobranch fish species due to a better maintenance of sensory, biochemical and microbiological quality, thus facilitating its commercialization.     

Effect of Treating of Squid with Sodium Chloride in Combination with Oxidising Agent on Bleaching,Physical and Chemical Changes During Frozen Storage

Pink discolouration is a problem faced in the squid processing industry, and some treatments have been implemented to tackle such a problem. The study aimed to elucidate the impact of NaCl in combination with oxidising agents on the quality changes of squid during frozen storage. The effects of treatment of pink squid using 3% (w/v) NaCl solution containing oxidising agents (0.05–0.5% (w/v) H₂O₂ or 0–10 ppm NaOCl) on colour and chemical and physical changes of squid during frozen storage were investigated. The lowest decreases in a*, b* values, ∆E* and ∆C* of squid were obtained with the treatment using 3% NaCl solution containing 0.5% H₂O₂. Nevertheless, NaOCl (0–10 ppm) had no impact on a* and b* values. During frozen storage at −18 °C for 10 weeks, fresh squid, pink squid samples without and with treatments with 3% NaCl solution containing 0.5% H₂O₂ had no changes in a* and b* values during frozen storage. Nevertheless, thiobarbituric acid reactive substances value, disulphide bond content, thaw drip and shear force were more pronounced in treated pink squid, compared with pink squid without treatment (control) and fresh squid, respectively, during the extended storage (p < 0.05). Higher denaturation and aggregation of muscle proteins during frozen storage were observed in treated pink squid than that without treatment and fresh squid, respectively. Therefore, pink squid treated with oxidising agent was prone to protein aggregation and denaturation during the extended frozen storage, though it could lower the pink colour. Therefore, fresh squid without treatment using oxidising agent is recommended for production of frozen squid with negligible loss in quality during extended storage.     

Effects of storage time and thermal treatment on the nutritive value of squid (Illex argentinus)

The storage (-28 degrees C) of squids prior to thermal treatment (steaming at 100 degrees C and autoclaving at 115 degrees C) was found to exert no significant influence on the available lysine and tryptophan contents of the flesh stored for no longer than 9-10 months. During a longer period of storage the contents of the studied amino acids decreased by 22.2% on an average. The -SH groups content and weight losses after thermal treatment were increasing with the time of frozen storage. The colour of squid flesh, as measured with a and b indicators (LAB system), changed most in the autoclaved samples, the colour changing towards yellow-red.     

Effects of storage in slurry ice on the microbial,chemical and sensory quality and on the shelf life of farmed turbot (Psetta maxima)

The application of slurry ice, a binary mixture of small spherical ice crystals surrounded by seawater at subzero temperature, is a potentially new preservation method for farmed turbot (Psetta maxima), a flat fish species of increasing commercial interest. Comparative biochemical, microbiological and sensory analyses were carried on turbot specimens stored in either slurry ice or flake ice for up to 40 days. The results obtained in the sensory analysis correlated well with the observed chemical and microbial changes. Storage of turbot in slurry ice resulted in a slowing-down of the nucleotide degradation pathway and lipid oxidation mechanisms. A good stabilisation of the high molecular weight protein fraction of turbot muscle was also achieved as a consequence of storage in slurry ice. A slower production of both trimethylamine and total volatile bases was also observed. Likewise, low levels of total aerobes, anaerobes, coliforms, and proteolytic bacteria were attained. The application of slurry ice to farmed turbot is advisable to achieve better quality maintenance during storage and distribution.     

乌贼墨多糖对冷藏鱿鱼的防腐保鲜作用研究

使用从乌贼墨中提取的活性多糖对低温储藏的鱿鱼进行处理,通过测定细菌总数、挥发性盐基氮(TVBN)值、pH 值,并作感官评定来探讨其防腐作用。结果表明：乌贼墨多糖对冷冻鱿鱼有较好的防腐抗菌作用,多糖的最佳作用pH 值为7.00,最佳使用质量浓度为7mg/mL;完全浸泡保藏的效果较浸泡20min 后沥干的要好;在防腐抗菌效果上乌贼墨多糖的作用低于同质量浓度的山梨酸钾和壳聚糖,综合来看,7mg/mL的乌贼墨多糖和1mg/mL的山梨酸钾、3mg/mL 的壳聚糖效果相当。     

Instrumental and sensory evaluation of cooked pasta during frozen storage

Food consumption patterns have changed significantly during the last years, showing an increase in the consumption of convenience foods. Frozen foods represent an important segment of this market. The aim of the present paper was to study the influence of frozen storage on the quality of cooked organic tagliatelle. Instrumental measurements of different quality parameters (moisture content, colour, textural and rheological characteristics of frozen cooked pasta) were performed during twelve months of storage. The sensory properties of pasta were also evaluated by means of an acceptability study. In general, both instrumental and sensory analysis found that frozen storage affects negatively the acceptability of cooked pasta. The advantages obtained through fast freezing procedures are not maintained along storage, being hardness (instrumental) and consistency (sensory) the most relevant quality indices. Finally, the shelf life of the product was calculated as 3.6 and 3.8 months in the cryogenic device and air‐blast tunnel, respectively, based on simple kinetic models.