Presence of synthetic antioxidants in organic and conventional milk

Samples of conventional (n = 11) and organic (n = 81) milk, both raw and heat-treated, were analysed for the presence of synthetic antioxidants (butylated hydroxytoluene, butylated hydroxyanisole, dodecyl gallate, propyl gallate and octyl gallate) to verify whether those labelled as “organic” corresponded to EU Regulations on the use of additives in such products. The analysis detected only the antioxidant BHT and its aldehyde BHT–CHO in all 11 conventional milk and in 18 of 81 organic milk samples. The investigation highlights the importance of strict control of organic dairy production, since synthetic antioxidants added to feedstuff to prevent rancidity can be transferred to milk.     

无水奶油和BL-41的比例对淡奶油稳定性的影响

研究了无水奶油和BL-41两种油脂之间不同的比例对淡奶油粒径分布、界面蛋白含量、脂肪部分聚结率及表观粘度的影响,并在此基础上探讨了其作用机理。研究结果表明,随着BL-41比例的不断增大,淡奶油的上层粒径d3,2、脂肪部分聚结率和表观粘度呈先增大后减小的趋势,在无水奶油∶BL-41为17.5∶17.5时达到最大值,而界面蛋白含量则先降低后升高,在无水奶油∶BL-41为17.5∶17.5时达到最小值。此外,随着储存时间的延长,上层粒径d3,2、脂肪部分聚结率和表观粘度均逐渐增大,而界面蛋白含量则逐渐降低。      

Effectiveness of a natural Rosemary (Rosmarinus officinalis) extract on the stability of filleted and minced fish during frozen storage

 The objective of this study was to evaluate the effect of adding a natural Rosemary (Rosmarinus officinalis L.) extract to filleted and minced frozen fish and to compare the fat stability of the samples with that of the controls. Horse mackerel (Trachurus trachurus), a relatively fatty fish, and Mediterranean hake (Merluccius mediterraneus), a low-fat fish, were used. Fat stability evaluation was done by comparing the changes of the malondialdehyde (MDA) content and the percentage of polyunsaturated fatty acid (PUFAs) degradation that occurred during frozen storage at –18°C for 120 days. Total volatile bases-N (TVB-N) were also measured to assess for quality. The results showed that the natural antioxidant extract retarded the oxidation process throughout storage. The control samples of both filleted and minced frozen fish of both species showed a significant reduction (^* P <0.05) of PUFAs until day 50 of storage, while the oxidation was gradual but slower in the treated samples. Fillets and minced samples of both species treated with antioxidant contained significantly (^* P <0.05) less MDA compared with the controls during storage. Received: 2 December 1996     

Effectiveness of a natural Rosemary (Rosmarinus officinalis) extract on the stability of filleted and minced fish during frozen storage

 The objective of this study was to evaluate the effect of adding a natural Rosemary (Rosmarinus officinalis L.) extract to filleted and minced frozen fish and to compare the fat stability of the samples with that of the controls. Horse mackerel (Trachurus trachurus), a relatively fatty fish, and Mediterranean hake (Merluccius mediterraneus), a low-fat fish, were used. Fat stability evaluation was done by comparing the changes of the malondialdehyde (MDA) content and the percentage of polyunsaturated fatty acid (PUFAs) degradation that occurred during frozen storage at –18°C for 120 days. Total volatile bases-N (TVB-N) were also measured to assess for quality. The results showed that the natural antioxidant extract retarded the oxidation process throughout storage. The control samples of both filleted and minced frozen fish of both species showed a significant reduction (^* P <0.05) of PUFAs until day 50 of storage, while the oxidation was gradual but slower in the treated samples. Fillets and minced samples of both species treated with antioxidant contained significantly (^* P <0.05) less MDA compared with the controls during storage. Received: 2 December 1996     

Effect of relative humidity and light conditions on the oxidative stability of sunflower oil blends stabilised with synthetic and natural antioxidants

The effect of relative humidity (RH) and light conditions on the oxidative stability of sunflower oil (SO) stabilised with oleoresin rosemary + ascorbyl palmitate (SOR), sage + ascorbyl palmitate (SOS) and tertiary butyl hydroquinone (SOT) was investigated. The SO without additive (SOC) served as positive control. Oil samples were subjected to 3 RH (29%, 52% and 75%) and two light conditions (dark, D and fluorescent light (600 lx), L) at 60 °C for 7 days. The oxidative stability was monitored by peroxide value (PV), conjugated diene value (CDV), free fatty acids (FFAs) and Rancimat induction period (IP). A direct relationship was noted between RH and increase in PV, CDV and FFA levels irrespective of light conditions. The detrimental effect of light on the oxidative stability was prominently noted at higher RH (75%) which followed an order: SOC > SOT > SOR > SOS. The samples stored under lower RH (29% and 52%), and dark conditions were better stabilised than light‐exposed counterparts.     

天然牛乳脂肪分离及应用研究进展

牛乳脂肪(乳脂)是一种天然的牛奶成分,主要加工成稀奶油、奶油和奶油粉等产品,具有良好的风味和营养价值。随着人们对乳脂营养价值及风味的认识更为全面,我国天然乳脂消费和加工逐年增加。为了扩大乳脂产品的应用范围,越来越多的改性技术被用于优化乳脂类产品,本文对适用于乳脂的不同物理改性技术进行了综述,着重探讨以干法分提为主的现有改性技术中存在的问题和局限,并概述了干法分提技术在奶油产品中的应用,从而为乳脂深加工提供参考。     

Antioxidant potential of synthetic and natural antioxidants and its effect on warmed-over-flavour in different species of meat

The role of natural antioxidants, e.g. Maillard reaction products (MRPs 60 mM/2 h), ascorbic acid (500 ppm), cloves (Eugenia caryophyllata) (250 mg/100 g), cinnamon (Cinnamomum zeylanicum) (250 mg/100 g) and synthetic antioxidants, e.g. tertiary butyl hydroxy quinone (TBHQ), butylated hydroxy anisole (BHA) and propyl gallate (PG), at 0.02% level each, in controlling the warmed-over-flavour (WOF), and non-haem iron release, as well as their potential in cooked and refrigerated stored meats from three common domestic species (sheep, beef and pork) has been investigated. MRPs and TBHQ showed good antioxidant activity (82–91%) and were significantly different (P < 0.05) from the other treatments in all three species. Significantly (P < 0.05) lower values of hexanal and non-haem iron were obtained for MRPs and TBHQ treated samples, which showed ability to control WOF during refrigerated storage. Non-linear correlation regression analysis was performed between non-haem iron, WOF values and antioxidant activity in all three species. Exponential fit equations were established for beef and pork, while for sheep, the relationship was found to be polynomial with correlation coefficients ranging from 0.90 to 0.97 for non-haem iron and WOF, respectively. The susceptibility of these species to lipid oxidation was in the order, pork > beef > sheep, and the order of antioxidant activity for the natural antioxidants was MRPs > cloves > ascorbic acid >  cinnamon; for synthetics it was TBHQ > BHA > PG.     

The effects of Asparagus racemosus (shatavari) extract on oxidative stability of ghee,in relation to added natural and synthetic antioxidants

The potential of Asparagus racemosus (shatavari) extract was evaluated in comparison with natural (rosemary, green tea) and synthetic (butylated hydroxyanisole, tert‐butyl hydroquinone) antioxidants, in ghee using accelerated oxidation tests. Its aqueous and ethanolic extracts significantly retarded deterioration of ghee relative to the control (without addition of synthetic or natural herb extract), as observed in peroxide value (8.3, 13.2 and 25.8 mmolO₂/g fat respectively), conjugated diene% (1.30, 1.44 and 1.78, respectively), radical‐scavenging potential (40.0, 25 and 5.5% inhibition, respectively) and oxidative stability index (16.8, 13.5 and 10.3 h respectively) after 21 days. However, these were less effective than the natural and synthetic antioxidants. The ethanolic extract of shatavari, having polyphenol content of 24.99 ± 0.74 mg gallic acid equivalent/g, exhibited some antioxidative and radical‐scavenging activities.     

Enhancing aspalathin stability in rooibos (Aspalathus linearis) ready-to-drink iced teas during storage: the role of nano-emulsification and beverage ingredients, citric and ascorbic acids

BACKGROUND: The effects of citric and ascorbic acids on the stability of aspalathin in rooibos (Aspalathus linearis) ready‐to‐drink (RTD) formulations containing fermented rooibos extract (FR), aspalathin‐enriched green rooibos extract (GR) and aspalathin‐enriched green rooibos extract ascorbic acid solubilisate (GR‐solubilisate) were investigated during storage (12 weeks at 25 °C). RESULTS: Storage of iced tea formulations containing FR and GR extracts reduced their flavonoid content. The aspalathin content of FR iced tea without citric or ascorbic acid was reduced to undetectable levels by week 8 of storage. Addition of citric acid resulted in improved stability of aspalathin, but ascorbic acid did not impart additional stability. Iso‐orientin and orientin were less affected than aspalathin, presumably owing to partial conversion of aspalathin to these flavones. Similar results were obtained for GR iced tea formulations. Improved stability of aspalathin was noted in iced tea containing GR‐solubilisate with or without citric acid. Lower pH was shown to favour stability, especially for fermented rooibos iced teas. CONCLUSION: Citric and ascorbic acids contribute to the stability of rooibos flavonoids during storage. Differences in stability between formulations are not due to pH differences but may be related to the matrix. Copyright © 2011 Society of Chemical Industry