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。     

Influence of packaging material on pomegranate juice colour and bioactive compounds,during storage

Pomegranate juices were assessed after pasteurisation and storage in different packaging materials: transparent and green glass, and paperboard carton with polyethylene layers (Minibrik‐200). The main objective was to establish the influence of the container on the stability of colour and bioactive compounds (anthocyanins, ellagic acid and other non‐coloured phenols). Results showed that non‐coloured phenols and ellagic acid were quite stable during the storage period. In contrast, anthocyanins degraded, to an extent directly proportional to colour loss, less for those juices stored in glass bottles than for those stored in Minibrik. These results indicated that these paperboard carton containers are oxygen permeable, and that oxygen has a greater influence on anthocyanin, and consequently on colour degradation, than light on pomegranate juice during storage. Nevertheless, the antioxidant activity was not influenced by the packaging material employed. Copyright © 2004 Society of Chemical Industry     

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。     

油脂无氧包装工艺设计

为完善油脂抗氧化包装工艺,针对目前油脂抗氧化包装中存在的问题,提出油脂无氧包装的概念。在对油脂抗氧化包装现状分析的基础上,提出油脂抗氧化效果评价的综合指标,包括无损抗氧化、全程抗氧化、有效抗氧化,并对其内容进行了详细阐述。根据油脂抗氧化效果评价综合指标,设计油脂无氧包装工艺,并提出油脂无氧包装工艺要求。按照油脂无氧包装工艺要求,对其各工序进行工艺、结构等设计,保证油脂无氧包装工艺的可行性与可靠性。研究所提出的油脂无氧包装工艺可以最大限度地保护油脂内对人体有益的物质,且有效延长了油脂的保质期,具有一定的实用价值。     

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。     

食用油储罐更新改造技术应用研究

介绍了食用油罐更新改造技术应用的工作原理、构成、操作步骤。技术内容包括:油罐制造、充氮保护、油品加热及实时检测油罐液位、温度。该技术可有效节省油罐占地,避免储存油脂发生氧化,降低储存损耗。     

Preparation and characterization of kafirin‐quercetin film for packaging cod during cold storage

This study mainly evaluated the physical properties of kafirin‐quercetin (KQ) edible films and their application on the quality of cod fillets during cold storage. The results showed that the addition of quercetin significantly increased mechanical properties of KQ films, while decreased water vapor permeability, water solubility, and transparency. As quercetin was 0.4% (wt/vol), the film had the highest tensile strength (4.96 ± 1.23 MPa), the lowest water vapor permeability (1.08 ± 0.09 g·mm·m^?2·h·KPa^?1) and water solubility (22.02 ± 0.45%). Moreover, compared with the pure kafirin and polythylene films, KQ films could effectively inhibit the cod meat deterioration by restraining the growth of microorganisms and decreasing TVB‐N and TBARs. The KQ_0.4% film was the best to prolong the shelf life of cod fillets during cold storage. Therefore, KQ edible films could be used as a potential food packaging material to protect and retain the quality of aquatic products.     

不同薄膜包装对冷藏空心菜采后品质的影响

为探讨不同薄膜包装对空心菜采后品质的影响,文中以‘竹叶’空心菜为试验材料,在(5±1)℃贮藏条件下(90%⁹5%RH),研究了3种不同厚度薄膜(CK,32.70μm带孔聚乙烯袋;P1,32.70μm聚乙烯袋;P2,12.75μm聚乙烯袋)包装对空心菜(茎、叶)贮藏品质的影响。结果表明:与对照相比,薄膜包装可有效提高空心菜品质,延缓其黄化进程,维持空心菜较高的生理活性,其中P1组的效果最为理想。相比P2及对照,P1组可显著延缓空心菜叶绿素分解,促进可滴定酸积累,维持其较高的总酚含量及抗氧化活性。P1可有效维持采后空心菜的品质,这与其包装袋微环境中的高CO2浓度(1.6%95%RH),研究了3种不同厚度薄膜(CK,32.70μm带孔聚乙烯袋;P1,32.70μm聚乙烯袋;P2,12.75μm聚乙烯袋)包装对空心菜(茎、叶)贮藏品质的影响。结果表明:与对照相比,薄膜包装可有效提高空心菜品质,延缓其黄化进程,维持空心菜较高的生理活性,其中P1组的效果最为理想。相比P2及对照,P1组可显著延缓空心菜叶绿素分解,促进可滴定酸积累,维持其较高的总酚含量及抗氧化活性。P1可有效维持采后空心菜的品质,这与其包装袋微环境中的高CO2浓度(1.6%².1%)和低O2浓度(14.8%2.1%)和低O2浓度(14.8%¹7.5%)有关。     

包装材料、储存环境及储油罐充氮对亚麻籽油保质期的影响

亚麻籽油富含多不饱和脂肪酸,易氧化,保质期较短。以过氧化值为评价指标,研究包装材料、储存环境及储油罐充氮对亚麻籽油保质期的影响。结果表明：避光包装材料、暗光条件储存,亚麻籽油的保质期可适当延长;不论什么包装材料的亚麻籽油,最佳食用时间限制在3个月内;包装瓶的气密性和灌装压盖的质量一定程度上影响亚麻籽油的保质期;储油罐间歇充氮方式较连续充氮方式节能,两者效用相同,均可延长亚麻籽油的保质期。     

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。     

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.     

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.     

Development of anti-insect food packaging film containing a polyvinyl alcohol and cinnamon oil emulsion at a pilot plant scale

Anti-insect packaging films containing cinnamon oil (CO) encapsulated by polyvinyl alcohol (PVA) for repelling Plodia interpunctella (Hübner) larvae were manufactured using pilot plant scale instruments. The microcapsule emulsion of CO and PVA was printed onto polypropylene (PP) film as an ink mixture using the gravure printing method. The printed PP film was then laminated with a low-density polyethylene (LDPE) film to protect the printed side. Four types of multilayer films were produced: control film, 2% CO film, encapsulated 1% CO film, and encapsulated 2% CO film. When mechanical properties were assessed, tensile strength and elongation-at-break were not significantly different among films, whereas the Young's modulus values were different between the control film and the three types of CO-containing films. In a repellent test, 2% CO film repelled P. interpunctella larvae most effectively. For sensory evaluation, which was performed using milk chocolate, caramel soft candy, and cookies packaged with the produced films, the produced films did not affect the sensory characteristics. Therefore, the films printed with emulsions of CO and PVA could be applied in the food industry to help protect foods from infestation by P. interpunctella.     

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.     

Cellulose nanoparticles synthesised from potato peel for the development of active packaging film for enhancement of shelf life of raw prawns (Penaeus monodon) during frozen storage

In this study, the cellulose nanoparticles (CNP) isolated from potato peel were used for reinforcement of polyvinyl alcohol (PVA)-based active packaging film. The above film was used to pack the raw prawns (Penaeus monodon) at −20 °C, and the colour change, protein content, TVB-N, TMA and microbial analysis were done at regular interval for prawns stored in CNP-PVA active packaging film. A significant difference was observed in the quality of prawns stored in potato CNP-PVA film compared with prawns packed and stored in polyethylene film. The newly designed active packaging with CNP and fennel seed oil enhanced the shelf life of prawns up to two months for both HOSO (head on shell on) prawn and PD (peeled and deveined) prawn. Hence, the study recommends the potato peel CNP-PVA film with fennel seed oil as better choice to extend the shelf life of the prawns during storage compared with polyethylene packaging.     

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.