The Effect of Stunning Methods on Rigor Mortis and Texture Properties of Atlantic Salmon (Salmo Salar)

Shear force and rigor mortis were used to evaluate the post‐mortem changes of muscle texture in Atlantic salmon (Salmo salar). The fish were either stunned with carbon dioxide (CO₂), electricity, or percussion prior to slaughter. The pre‐mortem stress during CO₂ stunning resulted in an earlier onset and resolution of rigor mortis, and accelerated post‐mortem softening of the muscle tissue as compared to the other stunning methods. No significant differences, either in development of rigor mortis or shear force, were seen between fish that were stunned with electricity or by percussion. Consequently electricity can be used for stunning fish prior to slaughter.     

Effects of slaughtering methods on sensory,chemical and microbiological quality of rainbow trout (<Emphasis Type="Italic">Onchorynchus mykiss</Emphasis>) stored in ice and MAP

The effects of slaughtering methods (percussive stunning and death in ice slurry) on the quality of rainbow trout stored in ice and modified atmosphere packing (MAP) (40% CO₂, 30% N₂ and 30% O₂) were investigated in terms of sensory, chemical and microbiological analysis. Sensory analysis showed that the demerit points of fish slaughtered by percussive stunning were higher than those slaughtered by the ice slurry method, but there were no significant differences in demerit points (P>0.05). In addition, the rate of increase in demerit points in fish in MAP was significantly (P>0.05) higher at 6 and 10 days of storage than that in fish in ice for each slaughter method, which was due to increased drip, the appearance of slime and the odour of the fish in MAP packing. The mean K values of rainbow trout slaughtered by percussive stunning in this study were significantly lower (P<0.05) than those of trout slaughtered according to the ice slurry method. The level of biogenic amines, regardless of the slaughter method, showed a similar trend (P>0.05), but higher concentrations of biogenic amines were found for the ice slurry slaughter method and for fish stored in ice. There were no significant differences (P>0.05) in total viable count of fish stored in ice and MAP, regardless of the different slaughter methods used. However, fish packed in MAP showed reduction in bacterial counts compared to fish held in ice throughout study. The results of this study showed that slaughter by percussive stunning improved the quality of trout compared to the ice slurry method.     

Evaluation of slaughtering methods for turbot with respect to animal welfare and flesh quality

After elaborating a suitable scheme to assess consciousness/unconsciousness of turbot, the effects on fish welfare of commercial and experimental slaughtering techniques were evaluated. Strong adverse reactions and slow loss of clinical reflexes were observed when fish were slaughtered by bleeding without prior anaesthesia. The efficiency of electricity (150 V for 2 s followed by 25 V for 5 min) as a stunning and killing technique was dependent on the current frequency and mode of administration, ie whether the electrical discharge was applied to the head only or throughout the whole body. Finally, percussion of the head with a mechanical device resulted in immediate and permanent loss of all responses and reflexes in all fish tested. Three methods were selected as a result of the preliminary tests (bleeding in ice slurry, whole‐body electrical treatment and percussion), and their influence on flesh quality was studied over a 9 day period. Fish killed by percussion were characterised by a higher pH and higher water content in the very early stage of post mortem storage, but also by a much delayed rigor mortis. In contrast, fish killed by electricity entered most rapidly into rigor mortis; their flesh was significantly softer (p < 0.05) throughout the entire storage time and was also redder and darker, as indicated by higher a* values (p < 0.001) and lower L* values (p < 0.01) respectively. It is suggested that automated percussion is a suitably humane method for the slaughter of farmed turbot. © 2002 Society of Chemical Industry     

Nitrogen stunning of rainbow trout

This study examined the use of nitrogen gas for stunning of Rainbow Trout. It was found that nitrogen could be used as an effective stunning method and that the strong aversive reaction reported for carbon dioxide stunning was not observed. Measurement of ATP, its metabolites and pH were carried out to evaluate the effects of nitrogen stunning on post mortem muscle biochemistry. This treatment was compared to percussive stunning and air asphyxiation. Post mortem ATP levels in nitrogen stunned fish (1.96 ± 0.36 μmol g^?1) were significantly higher than for asphyxiated fish (0.2 ± 0.11 μmol g^?1) but lower than values for percussively stunned fish (5.9 ± 0.89 μmol g^?1). This work indicates that the use of gasses other than carbon dioxide for stunning of fish deserves further study.     

The effects of carbon monoxide on Atlantic salmon (Salmo salar L.)

Atlantic salmon were exposed to carbon monoxide (CO) before the fish were percussively killed and gill cut. The fish were compared against a control group treated identically, without CO. Salmon exposed to CO expressed no adverse reactions and were easily stunned by percussion. CO-treated salmon had an earlier onset of rigor mortis and a faster decrease in muscle pH than the control group. No significant difference in drip loss was found between salmon treated with CO and the control. A significantly deeper red colour of both gills and fillets of CO-treated salmon was observed 10 days post mortem. Significantly higher levels of plasma lactate and potassium were found in CO-treated salmon compared to control, as well as a lower level of pCO₂. Exposure to CO did not increase plasma cortisol, sodium, haematocrit or glucose; however, lactate was high. Exposure of salmon or other fish to CO could improve quality and welfare when slaughtered.     

Solubility of carbon dioxide in a seafood model product with fish oil

The solubility of carbon dioxide (CO₂) in a seafood model product with various amounts of salmon oil was investigated. Differential scanning calorimetry analysis of the salmon oil gave an onset temperature for crystallization at ?14.75 ± 0.74 °C, showing that the oil was in liquid state in the temperature range used in this experiment (1–8 °C). Solubility of CO₂ in salmon oil in liquid state was similar to water, with the same temperature dependency as water. Increased storage temperature decreased the amount of dissolved CO₂ and increased the headspace CO₂ and headspace gas volume. Headspace gas composition at equilibrium was linearly (R ² = 0.979) related to the composition of the packaging gas, while increasing CO₂ in the packaging gas increased the headspace gas volume and the amount of dissolved CO₂ in the product. When designing modified gas-packaging regimes for products with marine fat, sum of fat and water can be used to estimate the amount of dissolved CO₂ in the product.     

The effects of electrical stunning and percussive captive bolt stunning on meat quality of cattle processed by Turkish slaughter procedures

The effects of electrical and percussive captive bolt stunning both on initial and up to 14 days post mortem meat quality of Friesian young bulls were studied. The first group (NS; n=10) were slaughtered without stunning under Turkish slaughter procedure (these animals were slaughtered under conditions acceptable to the appropriate ethics committee) in a modern abattoir. In the second group (ES; n=10) animals were electrically stunned. In the third group (PS; n=10) animals were stunned with percussive captive bolt. Meat quality was assessed by examining muscle glycogen concentration, pH and WHC. Also cooking loss, texture parameters and consumer sensory properties were assessed at 24 h, 4, 7 and 14 days post mortem. Meat colour as L^*, a^*, b^*, C^*, h^* values were evaluated at 0, 48 h, 3, 5, 7, 9 and 14 days post mortem. Pre-slaughter handling affected muscle glycogen concentration (P<0.05). Animals in electrical and percussive captive bolt stunned groups had higher muscle glycogen concentrations compared to animals in the non-stunned group (P<0.05). Although pre-slaughter handling did not affect significantly pH_{24 h} and WHC, differences were significant for cooking loss, colour coordinates and texture parameters at some storage times. For all sensory attributes (odour, flavour, tenderness and overall acceptability) at all ageing periods (24 h, 4, 7 and 14 days) the percussive stunned (PS) group was significantly superior to the non-stunned (NS) group. The electrically-stunned (ES) group also tended to be superior to the NS group although not all differences were statistically significant. These results indicate that percussive captive bolt stunning of cattle improved meat quality compared with cattle electrically stunned using head only tongs and those non stunned under approved Turkish slaughter procedure.     

Use of carbon dioxide enriched atmospheres in the refrigerated storage (2 °C) of salmon (Salmo salar ) steaks

 Selected microbial counts (total viable microbiota, Brochothrix thermosphacta, lactic acid bacteria and Enterobacteriaceae), biochemical parameters [pH, total volatile nitrogen, nucleotide breakdown products, non-volatile amines, d(–) and l(+)-lactic acids and short-chain fatty acids] and sensory attributes (colour and odour) of refrigerated (2  °C) salmon (Salmo salar) steaks stored under CO₂-enriched [CO₂/air (20/80, v/v), CO₂/air (40/60, v/v)] and air atmospheres were determined. When compared with air, sensory results showed shelf-life extension of 6 days and 15 days for 20% and 40% CO₂-enriched atmospheres, respectively. Microbial and biochemical results also revealed that the 40% CO₂-enriched atmosphere was the most effective packaging type for refrigerated salmon. Received: 22 April 1999     

Quantitative analysis of the isoflavone content and biological growth of soybean (Glycine max L.) at elevated temperature,CO2 level and N application

Effects of ambient and elevated CO₂ levels (360 and 650 µmol mol^?1 respectively), ambient and high (5 °C above ambient) temperatures and their interactions with N application on soybean (Glycine max L.) were studied in 2001. Overall, total isoflavones in whole soybean seeds were highest (1383.0 µg g^?1) in the elevated CO₂ (AE) treatment without N application and lowest (414.1 µg g^?1) in the elevated temperature (EA) treatment with N application. Malonylgenistin (449.2 µg g^?1) and malonyldaidzin (435.9 µg g^?1) concentrations in the AE treatment without N application were highest among the 12 individual isoflavones, while aglycon and acetyl conjugates showed lower concentrations (below 10 µg g^?1) than glucoside and malonyl conjugates in all treatments. Overall, N application had no effect on total isoflavone concentration, while both temperature and CO₂ level had a higher effect on increasing isoflavones, including aglycon and acetyl conjugates (P = 0.001). In the biological growth analysis, total dry weight was highest (100.9 g) in the elevated temperature and CO₂ (EE) treatment with N application, while leaf area was more affected by CO₂ than by temperature and increased with N application. There were larger numbers of pods (99) and seeds (176) per plant in the EE treatment with N application, and generally the AE treatment showed a greater increase in 100‐seed weight (g per 100 seeds) and in pods and seeds per plant than other treatments. Overall, total dry weight was highly affected (P = 0.001) by three main factors, temperature, CO₂ and N application, but the interactions temperature × N and temperature × CO₂× N did not affect total dry weight. Also, total dry weight tended to increase with increasing numbers of pods (r² = 0.93***) and seeds (r² = 0.93***) and larger leaf area (r² = 0.85***). In addition, numbers of pods and seeds were significantly affected (P = 0.01–0.001) by temperature, CO₂ and temperature × CO₂. Generally, elevated CO₂ and temperature did not affect N, P and K concentrations in the seeds but did decrease the concentrations of Ca and Mg, which were increased in the AE treatment. Among the nutrients, Ca and Mg were highly correlated with temperature and CO₂ level. N concentration in the seeds increased with applied N and in particular showed a high increase with elevated temperature and ambient CO₂ (EA treatment). The variation in isoflavones was correlated with temperature (r² = ?0.70**) and CO₂ (r² = 0.67**), while N application was not correlated with isoflavone concentration. Also, Ca (r² = ?0.85***) and Mg (r² = ?0.57*) in the seeds were correlated with variation in isoflavones. This indicated that isoflavones were in higher concentrations under conditions of low temperature and increasing CO₂, which also resulted in low Ca and Mg concentrations in the seeds. The results of this study suggest that the long‐term adaptation of the soybean to growth at elevated CO₂ level and high temperature might potentially increase its isoflavone content, growth and yield. Copyright © 2005 Society of Chemical Industry     

Effect of Minimal Processing Conditions on Respiration Rate of Carrots

ABSTRACT: Measurement, analysis, and modeling of respiration rate (RR) of fresh produce are fundamental for the engineering design of MAP. This study investigates the effect of type of cutting (sliced in circular shape, batons in rectangular shape, and shredded into thin strips) on the respiration rate of carrots at different temperatures (4, 8, 12, 16, and 20 °C) with ambient atmosphere. The higher respiration rates were found for shredded carrots and the lowest for whole carrots at all the temperatures tested. The RR increased from 9 ± 1 to 26 ± 3, 10 ± 1 to 53 ± 2, 11 ± 1 to 55 ± 2, and 18 ± 1 to 75 ± 3 mL of O₂ per kilogram hour for whole, sliced, baton, and shredded carrots, respectively, as the temperature increased from 4 to 20 °C. On an average, RO₂ and RCO₂ were increased by 85% and 64%, 100% and 72%, and 151% and 124% for sliced, baton, and shredded carrots, respectively, compared to the RR values of whole carrots. The temperature dependence of RR followed an Arrhenius‐type relationship for all types of carrots, with activation energies in the range of 35 ± 3 to 62 ± 2 kJ/mol. Type of cut was the major factor for both RO₂ and RCO₂, with shredded carrots having the highest rates and whole carrots the lowest. RR of whole carrots did not vary during storage, whereas it increased for cut carrots and especially for shredded carrots. The respiratory quotient (RQ) increased with temperature and did not vary during storage in all types of carrots, except the RQ of whole carrots decreased significantly over time.     

Effect of combined application of high pressure treatment and modified atmospheres on the shelf life of fresh Atlantic salmon

High pressure (HP) processing at low temperatures combined with modified atmosphere packaging (MA) was used for the preservation of salmon. A shelf life extension of 2 days was obtained after a HP treatment of 150 MPa for 10 min at 5°C compared to unpressurised, vacuum-packed salmon. MA storage (50% O₂+50% CO₂) alone extended the shelf life of salmon for 4 days at 5°C. When salmon had been subjected to HP treatment in the presence of 50% O₂+50% CO_2, the threshold value for microbial spoilage of salmon (7.0–7.2 log CFU/g) was not reached for at least 18 days at 5°C. Spoilage microorganisms (lactic acid bacteria, Shewanella putrefaciens) as well as pathogens (Listeria monocytogenes Scott A, Salmonella typhimurium) spiked on salmon prior to the treatment, were more susceptible to HP in the presence of 50% O₂+50% CO₂. The mode of action of compressed gases is probably related to intracellular formation of reactive oxygen species as well as to phase transition phenomena. Although microbial growth on salmon was retarded, the combined HP and MA treatments, at the settings used in this study, promoted a detrimental effect on colour and changes in the balance of oxidative rancidity.     

Methods of stunning freshwater fish: impact on meat quality and aspects of animal welfare

 Taking into account aspects of meat quality and animal welfare, three methods of stunning fish were compared: a manual technique (blow on the head, stab in the neck), one using electricity and one using CO₂. The following results were obtained using eel (n=72), carp (n=120) and trout (n=54). From the viewpoint of animal welfare, the effects on the fish were judged. Excitation and mucus secretion as well as the time taken for the fish to be anaesthetized were recorded. With manual and electrical stunning, all fish were anaesthetized almost immediately, while using CO₂ it took 3.2 min (trout), 9.2 min (carp) and 109.7 min (eel) on average. After slaughter and after 3 and 8 days of storage on ice, the fish meat quality parameters, i.e. pH value, water-holding capacity and rigor mortis, were measured. CO₂ stunning gave rise to the lowest pH values and water-holding capacities. Rigor mortis in carp and eel advanced the most. Testing of raw and prepared fish was performed by a panel assessing organoleptic properties. In many cases, fish anaesthetized manually were ranked to be better than those in the other groups. Received: 4 June 1996 / Revised version: 5 July 1996     

Effects of high oxygen concentration on pro- and anti-oxidant enzymes in peach fruits during postharvest periods

Peach fruits (Amygdalus persica cv. Okubao) were stored in air, controlled atmospheres (CA) of 5% O₂ plus 5% CO₂, or CA with high O₂ concentration (70% O₂ plus 0% CO₂ for 15 days, then in CA with 5% O₂ plus 5% CO₂) at 0 °C, to determine the effects of different O₂ and CO₂ atmospheres on the activities of lipoxygenase (LOX), peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT), as well as malondialdehyde (MDA) content and membrane integrity during storage periods with or without 3 days of post-storage ripening at 20 °C. SOD, CAT and POD activities of the fruits stored in air markedly decreased during the first 30 days of storage, while LOX activity increased after 15 days. CA (5% O₂ plus 5% CO₂) reduced chilling injury, and delayed the reduction of SOD, CAT and POD activities compared to the control. CA with high O₂ treatment induced SOD and CAT activities and maintained membrane integrity, but no significant effect on alleviating chilling injury was found compared to CA storage. The results indicated that the decrease of SOD and CAT might contribute to the development of chilling injury in peach fruits.     

Oxidative stability of previously frozen ostrich Muscularis iliofibularis packaged under different modified atmospheric conditions

This study investigated the aptness of modified atmospheric packaging (70:30, O₂:CO₂ (O_MAP); 70:30, N₂:CO₂ (N_MAP)) and traditional overwrap (control) for previously frozen ostrich steaks, stored at 4 ± 1 °C for 10 days. The N_MAP showed the least oxidation, O_MAP the highest and the control moderate. The redness (CIE a*) decreased to 3.67 ± 0.83 by day 10 in the O_MAP, the N_MAP and control initially had lower values indicating slower oxidisation. The free carbonyl production was higher in the O_MAP than the N_MAP and control. TBARS remained relatively constant for the N_MAP and control, but increased to 9.70 ± 3.26 (day 10) in the O_MAP. Drip loss (non‐cumulative), was initially high (5–6%) for N_MAP and control, followed by a decrease on day 2 (2%) that increased to day 10 (4–6%). In conclusion, the traditional overwrap was not suited; N_MAP holds potential under a true anoxic atmosphere whilst O_MAP was limited by protein and lipid oxidation.     

Methods of stunning freshwater fish: impact on meat quality and aspects of animal welfare

 Taking into account aspects of meat quality and animal welfare, three methods of stunning fish were compared: a manual technique (blow on the head, stab in the neck), one using electricity and one using CO₂. The following results were obtained using eel (n=72), carp (n=120) and trout (n=54). From the viewpoint of animal welfare, the effects on the fish were judged. Excitation and mucus secretion as well as the time taken for the fish to be anaesthetized were recorded. With manual and electrical stunning, all fish were anaesthetized almost immediately, while using CO₂ it took 3.2 min (trout), 9.2 min (carp) and 109.7 min (eel) on average. After slaughter and after 3 and 8 days of storage on ice, the fish meat quality parameters, i.e. pH value, water-holding capacity and rigor mortis, were measured. CO₂ stunning gave rise to the lowest pH values and water-holding capacities. Rigor mortis in carp and eel advanced the most. Testing of raw and prepared fish was performed by a panel assessing organoleptic properties. In many cases, fish anaesthetized manually were ranked to be better than those in the other groups. Received: 4 June 1996 / Revised version: 5 July 1996     

CONTROL OF CLOSTRIDIUM PERFRINGENS IN A MODEL ROAST BEEF BY SALTS OF ORGANIC ACIDS DURING CHILLING1

Control of Clostridium perfringens germination and outgrowth by the following salts of organic acids, sodium lactate [Purasal?S/SP (Purasal); 1.50, 3.00 and 4.80%], sodium lactate supplemented with sodium diacetate [Purasal? Opti.form? (Optiform), 1.50, 3.00 and 4.80%], buffered sodium citrate [Ional? (Ional), 0.75, 1.00 and 1.30]) and buffered sodium citrate supplemented with sodium diacetate [Ional Plus? (Ional Plus), 0.75, 1.00 and 1.30%] was evaluated during continuous chilling of a model roast beef product. Beef rounds were ground through an 1/8′’ plate and NaCl, potato starch and potassium tetra pyrophosphate were added to final concentrations of 0.85, 0.25 and 0.20%, respectively, and mixed. Portions (250 g) of the meat were mixed with either Purasal (1.5, 3.0 or 4.8%), Optiform (1.5, 3.0 or 4.8%), Ional (0.75, 1.0 or 1.3%) or Ional Plus (0.75, 1.0 or 1.3%) along with a control that did not have any added antimicrobials. Each product (10 g) inoculated with C. perfringens spores (ca. 2.2 log₁₀ spores/g) was packaged into vacuum bags (2 in. × 3 in.), vacuum sealed, heated to 60C within 1 h, and subsequently chilled from 54.4C to 7.2C in 18 or 21 h following exponential chilling rates. Products were sampled immediately after cooking to enumerate the C. perfringens populations (spores surviving heat treatment) and subsequent to chilling (total C. perfringens populations, including spores and vegetative cells resulting from germination and outgrowth of the spores). Chilling of cooked, model ground roast beef resulted in germination and outgrowth of C. perfringens spores; the population densities increased by 4.13 and 4.40 log₁₀ CFU/g, following 18 and 21 h chill rates, respectively. Incorporation of Purasal (1.5–4.8%), Optiform (1.5–4.8%), Ional and Ional Plus (0.75–1.3%) substantially (P ± 0.05) inhibited germination and outgrowth of C. perfringens spores. Incorporation of antimicrobial ingredients resulted in ± 1.0 log₁₀ CFU/g increase of the pathogen, except for model roast beef with Ional Plus at 0.75% concentration, following 18 h chilling rate. Similar results were obtained when 21 h chilling rate was followed, with roast beef containing ingredients (at all the concentrations) resulting in either reductions or ± 1.0 log₁₀ CFU/g growth in total C. perfringens populations, except for Purasal and Ional Plus at 1.5 and 0.75% concentrations, respectively. Use of sodium salts of organic acids in formulation of model roast beef can reduce the risk of C. perfringens spore germination and outgrowth during extended chilling rates.     

Effect of Carbon Dioxide Atmosphere on Microbial Growth and Quality of Salmon Slices

Salmon slices ( Salmo salar ) were packed under CO₂ and stored in a chill room at 2±1°C for 3 weeks. A study was carried out on the effect of CO₂ atmosphere on bacterial growth as well as on chemical deterioration (pH, total volatile bases, (TVB), trimethylamine (TMA), lipid oxidation) and sensory features (exudation, raw fish odour, cooked fish flavour). Results were compared with a control stored in air. Salmon slices stored under CO₂ had a shelf-life of nearly twice as long as those in air, having lower bacterial counts, pH, TMA and TVB, as well as improved sensory features after 18 days at 2±1°C. Exudation was not significantly different between control and CO₂-stored samples after 10 days ice storage. Exudate values extended from 1 to 2% for CO₂-stored samples after 10 and 20 days storage, respectively. Salmon slices can be stored under CO₂ at 2±1°C for about 18 days, with no substantial loss of quality. Shelf-life can vary depending upon the state of fish, handling practices, initial bacterial load and storage temperature.     

Effect of delay time before chilling on toughness in pork with high or low initial pH

Paired M. longissimus dorsi muscles from 56 carcasses of Danish Landrace and Yorkshire breeds, slaughtered at approximately 90 kg live weight, were utilized to study the potential of cold induced toughness in pork. Based upon the pH value 45 min post stunning, the carcasses were divided in two groups: a low (5·7 ≤ pH < 6·1) and a high one (6·1 ≤ pH ≤ 6·5). The effects on Warner-Bratzler shear force, sarcomere length and myofibril fragmentation of inserting a delay time of 0, 2 and 4 h before carcasses entered the chilling tunnel (operating at -28°C to -22°C) were investigated on early excised muscles as well as on muscles removed 30 h post stunning. The left LD muscle from each carcass served as a control while all right sides were used for treatments. pH and temperature measurements obtained from LD muscles left on carcasses during chilling showed that LD muscles belonging to the high pH group involve a risk of cold shortening even when a 2 h delay was used before passing in to the chilling tunnel. Comparing pH groups, however, sarcomere lengths did not differ in control sides whereas the Warner-Bratzler shear force values were significantly higher in LD muscles taken from the high pH group. Early excision of the LD muscle resulted in shorter sarcomere lengths and increased WB shear force only for carcasses belonging to the high pH group, which, however, could be avoided by introducing a 4 h delay time before rapid chilling. The effect of delay time on tenderness from muscles excised from the carcass 30 h post stunning was much less but a 4 h delay did significantly (P < 0·05) improve tenderness in carcasses with high initial pH. Coefficient of correlation between Warner-Bratzler shear force and sarcomere length was -0·12 and nonsignificant in the low pH group, whereas it was -0·57 and highly significant in the high pH group.     

Effect of chill storage under different icing conditions on sensory and physical properties of canned farmed salmon (Oncorhynchus kisutch)

This work focuses the sensory and physical properties of canned farmed coho salmon (Oncorhynchus kisutch); the effect of flake ice and slurry ice as previous slaughter and chilling conditions was studied. Hydrolytic chemical changes related to sensory and physical properties were also evaluated in canned salmon. Thermal treatment led to a canned muscle showing higher firmness, lower cohesivity and colour changes (higher L* and b* values; lower a* values); filling oils showed higher turbidity scores and lower L*, a* and b* values than starting oil. Additionally, oxidised and putrid odour development in canned muscle and filling oil was low. However, previous icing condition and time (up to 9 days) provided no changes in canned muscle and filling oil, except for an increasing oxidised odour and turbidity in filling oil with chilling time. Meantime, free fatty acid formation and K value were markedly affected by previous icing system and time.