Salmon by-product storage and oil extraction

Oils extracted from wild salmon by-products are excellent sources of long chain omega-3 polyunsaturated fatty acids including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). However, quality loss is expected if time delays are encountered before oil extraction. The free fatty acid levels (FFA), fatty acid profile and total fat soluble antioxidant activity in extracted oil from aging pink salmon heads and viscera stored at two temperatures (6 and 15 °C) for four days were determined. The FFA values in raw salmon heads and viscera increased with storage time and temperature. A significant difference (p < 0.05) from the starting material was noted at day 1 at both temperatures for FFA. Fatty acid composition data indicated no changes in the levels of long-chain omega-3 fatty acids with the respective temperature. The concentration of long-chain omega-3 fatty acids EPA ranged from 9.3 to 11.3 g/100 g of crude oil and DHA ranged from 12.3 to 13.1 g/100 g of crude oil. The antioxidant activity of the pink salmon oils at day 0 was 0.89 ± 0.15 μmole Trolox equivalent/g of crude oil. Significant decreases (p < 0.05) from the starting material were noted on day 2 for 15 °C samples and day 3 for 6 °C samples. After four days of storage antioxidant levels (Trolox equivalent/g of crude oil) were approximately 25% of initial values. Oil extracted from raw salmon heads and viscera remained a good source of long chain omega-3 fatty acids even after 4 days of raw material storage at 15 °C; however, fat soluble antioxidant activity was reduced and free fatty acid levels increased with increased raw material storage temperature and time.     

包装薄膜对鲜切莴笋品质的影响

以普通塑料薄膜保鲜袋作对照,研究不同包装薄膜(0.03mm聚氯乙烯薄膜、0.03mm聚乙烯薄膜、0.03mm微孔薄膜)对鲜切莴笋贮藏期间品质的影响。结果表明:0.03mm厚聚乙烯薄膜包装能有效地控制鲜切莴笋的失重率、褐变度、呼吸强度、Vc损失率,提高鲜切莴笋的感官品质和营养价值。     

Production and characterisation of skate skin gelatin films incorporated with thyme essential oil and their application in chicken tenderloin packaging

In this study, skate skin gelatin (SSG) was used as a new biodegradable film source and a SSG film was prepared. In addition, thyme essential oil (TEO) was incorporated in the SSG film as an antimicrobial agent for the preparation of an antimicrobial film. The tensile strength (TS) of the film decreased, whereas elongation at break (E) increased by the addition of TEO. The SSG film containing TEO showed increased antimicrobial activity against Listeria monocytogenes and Escherichia coli O157:H7 as TEO concentration increased. To apply the SSG film to food packaging, chicken tenderloin samples were wrapped with the film containing 1% TEO. The packaging of chicken tenderloin with the TEO‐containing SSG film inhibited the growth of L. monocytogenes and E. coli O157:H7 compared to the control during storage. Therefore, the SSG film with added TEO has potential as active food packaging to extend the shelf life of chicken tenderloin.     

Improvement of active chitosan film properties with rosemary essential oil for food packaging

Rosemary essential oil (REO) was used to develop an active film from chitosan. The effects of REO concentration (0.5, 1.0 and 1.5% v/v) on film properties were studied by measuring the physical, mechanical and optical properties of the REO‐loaded films. Scanning electron microscopy and Fourier transform infrared (FTIR) spectroscopy were used to study microstructure and the interaction of the chitosan‐based films. The solubility and water gain of the chitosan film decreased about 25% and 85%, respectively, by REO incorporation, up to 1.5% v/v, because of the interaction between hydrophilic groups of chitosan and REO as confirmed by FTIR. It was determined that REO improved the transparency of the films from 4.97 in neat chitosan up to 7.61; moreover, it reduced the films’ light transmission in UV light more than 25%. Films containing REO showed more antibacterial activity and total phenol content. The films containing REO showed potential to be used as active film in food preservation.     

塑料薄膜包装对常温和低温条件下枸杞鲜果主要贮藏性状的影响

研究了常温和低温条件下塑料薄膜包装对枸杞鲜果贮藏过程中主要贮藏特性及品质的影响。结果表明:无论是常温还是低温,薄膜包装均可显著降低果实失重率,保持良好的外观和口感,但提高了果实的腐烂率,薄膜包装的果实可溶性固形物和可滴定酸含量均明显低于未包装的对照;低温不仅可以有效减少果实腐烂,维持较好的感官品质,而且可延缓可溶性固形物和可滴定酸含量的下降。由此表明,低温结合薄膜包装可有效延长枸杞鲜果贮藏期,保持果实品质。     

菠菜的薄膜包装冷藏效果研究

对照菠菜贮藏中失水严重,导致外观萎缩,9℃下贮藏的严重黄化。菠菜用塑料薄膜不扎口包装结合2℃低温贮藏,可显著抑制其失水、黄化和腐烂,保持菠菜外观新鲜,其贮藏期达2个月。9℃条件下贮藏时,塑料薄膜不扎口包装虽显著抑制菠菜失水,但导致菠菜严重腐烂。     

托盘和真空包装对冷却猪肉中MetMb还原活性的影响

在冷却肉的贮藏过程中,其肌红蛋白(Mb)被氧化为高铁肌红蛋白(MetMb),导致了冷却肉的褐变。研究了托盘包装和真空包装条件下,冷却肉自身的还原系统活性变化规律及其对肉色稳定性的影响。在2周的贮藏期内,真空与托盘包装冷却肉糜肌浆蛋白粗提液的还原活性持续下降;但真空包装组MetMb还原酶粗提液还原活力第1天到第14天活性差异不显著,托盘包装组前后差异显著。真空包装组在贮藏期间MetMb含量持续下降,但托盘包装组MetMb含量则持续上升,说明无氧条件有利于MetMb的还原。托盘包装组TBA在贮藏期间持续上生,但真空包装组TBA变化不明显。结果表明,托盘包装不利于冷却肉自身MetMb还原能力的维持,而真空包装的无氧环境,有利于MetMb的还原和肉色的保持。     

Oxidative stability of fish oil supplemented with carnosic acid compared with synthetic antioxidants during long-term storage

The effects of carnosic acid (CA) of different concentrations (0.1, 0.2, and 0.3 mg/g) and synthetic antioxidants on oxidative stability in fish oil stored for 66 days at different temperatures (30 and 4 °C) were compared. The investigation focused on the increase in peroxide and conjugated diene values, as well as free fatty acid and thiobarbituric acid-reactive substances. The changes in trans fatty acid and aldehyde compound contents were investigated by Fourier transform infrared spectroscopy, while the changes in polyunsaturated fatty acid content were monitored by gas chromatography–mass spectrometry. The results show that the three CA concentrations were more effective in restraining fish oil oxidation, in which a dose–response relationship was observed. The antioxidant activity of CA was stronger than that of vitamin E, but still weaker than that of tertiary-butyl hydroquinone. Fish oil supplemented with 0.2 mg/g CA exhibited favourable antioxidant effects and is preferable for effectively avoiding oxidation.     

The role of some antioxidants in the HPMC film properties and lipid protection in coated toasted almonds

Hydroxypropylmethylcellulose based edible films with and without antioxidant additives were characterised as to their microstructure, water vapour and oxygen permeability, mechanical behaviour, optical properties and protective ability against lipid oxidation. The corresponding film-forming dispersions were also used to coat toasted almonds in order to test their effectiveness at protecting against rancidity development. The efficiency of three additives (ascorbic acid, citric acid or ginger essential oil) was tested and compared with antioxidant-free coatings. A cross-linking effect in the film matrices containing ascorbic or citric acid was detected through the analysis of the film microstructure, mechanical behaviour and barrier properties to oxygen and water vapour. These films were the most effective protectors against oxidation of almonds, due to both their antioxidant effect and the tighter structure which leads to lower oxygen permeability. In films with ginger oil, the hydrophobic effect markedly reduced water vapour permeability at low temperatures, but protection against lipid oxidation was less effective at long storage times.     

Changes in lipids during different sterilizing conditions in canning albacore (Thunnus alalunga) in oil

The effects on muscle lipid deterioration of initial cooking and of three time/temperature processing combinations after 4 months storage of albacore tuna canned in oil were studied. Conjugated dienes only increased slightly on cooking but thiobarbituric acid index increased and fell on canning; free fatty acids (FFA) increased with some canning. Polyene index and polyunsaturated fatty acids (PUFA) content provided higher values with higher temperature, shorter time processing.     

Enrichment of food products with polyunsaturated fatty acids by fish oil addition

Fish oil remains the main dietary source of long chain polyunsaturated fatty acids omega-3, which desirably impact on human health. Increase of omega-3 fatty acids intake is currently recommended. Results of many studies showed that consumption of food products enriched with fish oil offers the potential health benefits, especially in protection against cardiovascular diseases (CVD), cancer and improvement of brain development and function. Health influence, methods, advantages and disadvantages of food enrichment with fish oil as well as characteristics of market of such products were presented.     

Microencapsulation of fish oil by freeze-drying techniques and influence of process parameters on oxidative stability during storage

Dried microencapsulated fish oils (DMFO) were obtained by freeze-drying and the influence of various process parameters on oxidative stability was evaluated. Standard emulsions were composed of sandeel oil, sodium caseinate and lactose, homogenised by three passes at 40 MPa, frozen at −40°C, kept at −30°C and freeze-dried. In selected trials, carbohydrate, homogenisation pressure, freezing rate and initial temperature for freeze-drying were varied. DMFOs were stored at 25°C in the dark and oxidation monitored through anisidine values and polymer levels. Results showed no apparent relationships between oil globule size or microencapsulation efficiency and storage stability, and the only trial with significantly longer shelf-life involved fast-freezing in liquid nitrogen. Received: 24 November 1999     

Lipid damage during frozen storage of Atlantic halibut (Hippoglossus hippoglossus) in active packaging film containing antioxidants

The use of peroxide value (PV), free fatty acids (FFA), thiobarbituric acid reactive substances (TBARS) and p-anisidine value (PA) proved suitable for studying lipid hydrolysis and primary and secondary lipid oxidation in samples of Atlantic halibut throughout frozen storage. After twelve months, the FFA values in the samples packaged with the film containing natural antioxidants (extracted from barley husks) were similar to the FFA value in the control sample after 9 months. Maximum peroxide value in the samples packaged with the antioxidant-containing film was found one month after the maximum value observed in the control sample. After six months, the concentration of malondialdehyde in the control sample was approximately 30–50% higher than in samples packaged in film containing antioxidants. The results confirm the efficacy of natural antioxidants derived from barley husks and antioxidant active packaging film in slowing down lipid hydrolysis and increasing the oxidative stability of Atlantic halibut flesh.     

切割和包装对欧芹贮藏品质的影响

研究了切割和包装(50μmPE保鲜膜)对欧芹贮藏期间叶绿素、含水率、失重率和腐烂指数的影响。实验结果表明,包装切割处理抑制了叶绿素降解和失重率增加,保持了较高的含水率。贮期结束时包装切割的欧芹腐烂指数低于包装不切割处理,能够有效保持原有的外观和品质。     

Microencapsulation of fish oil by spray drying--impact on oxidative stability. Part 1

The aim of this study was to investigate the influence of spray drying on oxidative stability of dried microencapsulated fish oil (DMFO) coated with modified cellulose. DMFO samples were obtained by spray drying of prepared emulsions consisted of water solution of modified cellulose and fish oil. Appearance and size of particles were measured by electron microscopy and laser light microsizer. The oxidative stability of samples was evaluated by peroxide value measurements. Additionally the influence of different antioxidant substances on oxidative stability of the fish oil was investigated. It was observed that oxidation changes were much slower in bulk fish oil compared to DMFO. The most important factor determining shelf-life of the product was the access to air. It can be concluded, that the production of fish oil microcapsules by spray drying technique is possible, however its oxidative stability is not improved.     

脂肪含量和包装方式对法兰克福香肠贮藏品质的影响

以法兰克福香肠为研究对象,以脂质氧化、色泽、质构和挥发性产物为评价指标,研究不同脂肪含量和包装方式对产品贮藏品质的影响。结果表明:随着贮藏时间延长,法兰克福香肠的硫代巴比妥酸值(TBARS)值和亮度均与脂肪含量呈正相关,与包装方式无关;香肠的红度与脂肪含量相关性不显著,与包装方式呈正相关;香肠的硬度和黏性与脂肪含量呈负相关,与包装方式相关性甚小;脂肪含量和包装方式与挥发性产物之间的相关性都较显著。选择较低脂肪含量和真空包装方式有利于保持法兰克福香肠的贮藏品质。     

The use of packaging techniques to maintain freshness in fresh-cut fruits and vegetables: a review

Browning and other discolourations, softening, surface dehydration, water loss, translucency, off-flavour and off-odour development, as well as microbial spoilage are some of the most frequent causes of quality loss in fresh-cut products. Nowadays, the use of innovative modified atmospheres and edible coatings stands out among other techniques in the struggle for maintaining freshness and safety of fresh-cut fruits and vegetables. A few studies have demonstrated the effectiveness of these techniques when applied to different fresh-cut commodities. However, treatment and storage conditions for fresh-cut fruits are still being largely explored to better keep their fresh-like quality attributes. This review discusses the recent advances in the use of innovative modified atmosphere packaging (MAP) systems to maintain freshness of fresh-cut fruits and vegetables. Furthermore, special attention is devoted to the development of coatings that can be used as a complement or alternative to MAP.     

Stability of pigments and oil in pistachio kernels during storage

This work tested the stability of pigments (chlorophyll [chl] a and chlorophyll [chl] b, and lutein] and oil in pistachio kernels stored up to 14 months at three different temperatures: 10, 25 and 37 °C. The samples were hermetically packaged using two films (nylon and ethylene vinyl alcohol) with and without oxygen scavengers. For each temperature, reference samples were packaged in open bags. For both the oil and pigments, no differences were observed during storage, irrespective of packaging or oxygen scavengers. After 14 months, the oil showed very few changes: a slight increase in acidity and peroxide value (PV) irrespective of storage temperature; the spectrophotometric indices K₂₃₂ and K₂₆₈ remained the same. As for pigment stability, the lowest concentrations were observed at 37 °C with a degradation of about 62% for chl a, 44% for chl b and 57.5% for lutein. At 10 and 25 °C, the samples showed slight differences, the pigments degradations were about 46% for chl a, 33% for chl b and 37% for lutein. The degradation rate constants for the three pigments fitted a pseudo‐zero‐order kinetic in which Ea was 11.7 kJ mol^?1, 12.1 kJ mol^?1 and 18.2 kJ mol^?1 for chl a, chl b and lutein respectively.     

不同调湿包装对荔枝贮藏品质的影响

该研究以荔枝为实验对象,模拟常温物流,采用单层袋(聚乙烯醇薄膜保鲜袋)、双层袋(聚乙烯醇薄膜保鲜袋)+(聚乙烯保鲜袋)、CK(聚乙烯保鲜袋)包装荔枝,通过对外观品质、理化指标和营养成分变化规律的分析,研究透湿包装对荔枝贮藏品质影响.研究结果表明,单层袋、双层袋和CK包装处理荔枝贮藏4 d时腐烂率达到50％以上,贮藏6 ...