Fish oil replacement in rainbow trout diets and total dietary PUFA content : II) Effects on fatty acid metabolism and in vivo fatty acid bioconversion

This study aimed to gain a better understanding of the metabolic fate of dietary fatty acids in rainbow trout, with a specific focus on the effect of varying total C18 PUFA level. Fish were fed a control fish oil based diet or one of five experimental fish oil deprived diets formulated with a constant 1/1 ratio of 18:3n-3/18:2n-6 and varying total C18 PUFA levels for a period of 7 weeks. The transcriptional changes of the Δ-6 desaturase and elongase enzymes in direct comparison to in vivo fatty acid bioconversion, estimated using the whole-body fatty acid balance method, were analysed. The main findings were that i) the efficiency of Δ-6 desaturase was negatively affected by C18 PUFA availability, but the total apparent in vivo enzyme activity was directly proportional to C18 PUFA substrate availability; ii) Δ-6 desaturase had a greater affinity towards n-3PUFA than n-6PUFA; iii) excessive C18 PUFA substrate availability could limit the availability of Δ-6 desaturase to act on C24 fatty acid; iv) the elimination of dietary n-3LC-PUFA (enzyme products) up-regulated the transcription rate of Δ-6 desaturase; but v) the total apparent in vivo enzyme activity was directly and positively affected by substrate availability, and not product presence/absence nor the extent of the enzyme transcription rate.

Modelling the health impact of environmentally sustainable dietary scenarios in the UK

BACKGROUND/OBJECTIVES:


Food is responsible for around one-fifth of all greenhouse gas (GHG) emissions from products consumed in the UK, the largest contributor of which is meat and dairy. The Committee on Climate Change have modelled the impact on GHG emissions of three dietary scenarios for food consumption in the UK. This paper models the impact of the three scenarios on mortality from cardiovascular disease and cancer.
SUBJECTS/METHODS:


A previously published model (DIETRON) was used. The three scenarios were parameterised by fruit and vegetables, fibre, total fat, saturated fat, monounsaturated fatty acids, polyunsaturated fatty acids, cholesterol and salt using the 2008 Family Food Survey. A Monte Carlo simulation generated 95% credible intervals.
RESULTS:


Scenario 1 (50% reduction in meat and dairy replaced by fruit, vegetables and cereals: 19% reduction in GHG emissions) resulted in 36 910 (30 192 to 43 592) deaths delayed or averted per year. Scenario 2 (75% reduction in cow and sheep meat replaced by pigs and poultry: 9% reduction in GHG emissions) resulted in 1999 (1739 to 2389) deaths delayed or averted. Scenario 3 (50% reduction in pigs and poultry replaced with fruit, vegetables and cereals: 3% reduction in GHG emissions) resulted in 9297 (7288 to 11 301) deaths delayed or averted.
CONCLUSION:


Modelled results suggest that public health and climate change dietary goals are in broad alignment with the largest results in both domains occurring when consumption of all meat and dairy products are reduced. Further work in real-life settings is needed to confirm these results.

Quantitative determination of fatty acid compositions in micro-encapsulated fish-oil supplements using Fourier transform infrared (FTIR) spectroscopy

The research describes a rapid method for the determination of fatty acid (FA) contents in a micro-encapsulated fish-oil (μEFO) supplement by using attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopic technique and partial least square regression (PLSR) analysis. Using the ATR-FTIR technique, the μEFO powder samples can be directly analysed without any pre-treatment required, and our developed PLSR strategic approach based on the acquired spectral data led to production of a good linear calibration with R^₂ = 0.99. In addition, the subsequent predictions acquired from an independent validation set for the target FA compositions (i.e., total oil, total omega-3 fatty acids, EPA and DHA) were highly accurate when compared to the actual values obtained from standard GC-based technique, with plots between predicted versus actual values resulting in excellent linear fitting (R² ⩾ 0.96) in all cases. The study therefore demonstrated not only the substantial advantage of the ATR-FTIR technique in terms of rapidness and cost effectiveness, but also its potential application as a rapid, potentially automated, online monitoring technique for the routine analysis of FA composition in industrial processes when used together with the multivariate.

Molecular identification of marine yeast and its spectroscopic analysis establishes unsaturated fatty acid accumulation

Marine microbes are competent organisms, some of which can accumulate large amounts of lipids. A yeast strain, Rhodotorula mucilaginosa AMCQ8A was isolated from the marine water of the Queenscliff region, Victoria, Australia. The yeast isolate was identified by sequencing 18s rDNA genes. Scanning electron microscopy images revealed scars on the surface of the yeast cells. The Fourier transform infrared spectroscopy microspectroscopy studies demonstrated the presence of unsaturated fatty acids by differential microscopic analysis. The sharp band at 1745 cm^-1 was represented by ν(C=O) stretches of ester functional groups from lipids and fats, and therefore indicated the presence of total lipids produced by the cells. Over 65% of the fatty acids from the yeast strain were analyzed as C¹⁶ and C^18:1 with omega-3 content from about 6% to 7%. Thus, this marine-derived yeast could be a potential source of lipids, including omega-3 fatty acids. 2012, The Society for Biotechnology, Japan. All rights reserved.

Potential of cottonseed oil as fish oil replacer in European Sea Bass feed formulation

Triplicate groups of 20 European sea bass (35 g) were fed five diets in which the added lipid was 100% fish oil (FO), 40% (CSO40), 60% (CSO60), 80% (CSO80) and 100% (CSO100) refined cottonseed oil (CSO), for a period of 120 days. Overall fish growth, feed conversion ratio and protein utilization were unaffected by dietary treatment, but hepatosomatic and visceral fat indexes increased with increasing dietary CSO. Fillet fatty acid composition of total lipids reflected the fatty acids in the test diets. The monounsaturated fatty acids were significantly higher in fillet of fish fed diet FO, CSO40 and CSO60 compared to other treatments while saturated and polyunsaturated fatty acids (PUFA) were not affected by the dietary treatment. Some fatty acids (18:0, 18:1n-9, 20:5n-3 and 22:6n-3) were present in higher concentration in fillet lipid than in the CSO100 dietary lipid indicating accumulation in fillet relative to test diets. Retention of n-3 LC-PUFA within the fillet was increasingly inefficient among fish fed increasing levels of FO. Thus, this study suggests that CSO can be considered as a relatively effective substitute for fish oil in European sea bass (35 g) in terms of growth performances and feed efficiency as far as fish meal is present in the diet.

Changes in oil content, lipid class and fatty acid composition of the microalga Chaetoceros calcitrans over different phases of batch culture

 Abstract
The diatom Chaetoceros calcitrans is a microalgal species used as food for larva in aquaculture for many species worldwide. Chaetoceros calcitrans is an important source of omega 3 long chain (C ≥ 20) polyunsaturated fatty acids (n-3 LC PUFA), chiefly eicosapentaenoic acid (EPA, 20:5n-3). This article reports lipid content, lipid class composition and fatty acid profiles of each lipid class during the growth cycle of batch cultures of C. calcitrans. Total lipid content and the concentration of neutral lipid were highest in the late stationary growth phase (day 12). However, the amount of EPA was highest during the logarithmic growth phase (1.24 pg/cell on day 4). EPA was initially concentrated in the glycolipid fraction, but this fraction decreased during logarithmic growth, coinciding with the increase in neutral lipid. Docosahexaenoic acid (22:6n-3, DHA) (0.91 pg/cell) was reported as a major fatty acid (>10 mg/100 g) in all lipid classes on day 1. DHA was depleted quickly from the neutral lipid and glycolipid classes, but at a slower rate from the polar lipid fraction. This work confirms that C. calcitrans is a good source of lipid, in particular EPA, for larval and adult filter feeders in aquaculture.

Functionality of fatty acid chemoreception : a potential factor in the development of obesity?

Excess dietary fat consumption is recognized as a strong contributing factor in the development of overweight and obesity. Understanding why some individuals are better than others at regulating fat intake will become increasingly important and emerging associative evidence implicates attenuated fatty acid sensing in both the oral cavity and gastrointestinal (GI) tract in the development of obesity. Functional implications of impaired fatty acid chemoreception include diminished activation of the gustatory system, the cephalic response and satiety. This review will focus on knowledge from animal and human studies supporting the existence of oral fatty acid chemoreception including putative oral detection mechanisms, and how sensitivity to fatty acids is associated with fat consumption and fatty food preference.