Highest PV Research Articles

Freezing storage combined with freeze-drying of black soldier fly (Hermetia illucens) larvae to produce oil rich in free lauric acid

Abstract The fat of Hermetia illucens larvae (black soldier fly, BSFL) is a rich source of lauric acid (LA), and its free fatty acid (FFA) form holds valuable potential for applications in food, feed, pharmaceuticals, or cosmetics. This study aimed to establish specific processing conditions of BSFL that naturally promote lipolysis, resulting in a high free LA (FLA) rich oil. Freezing was used for slaughtering, with different times of frozen storage (1, 7 and 14 d). Then, thermal (oven-drying) and non-thermal (freeze-drying) drying processes were compared. Additionally, the impact of 24 h restrictive vs non-restrictive feeding before slaughtering was tested. Free acidity, free fatty acid profile, lipid oxidation (peroxide value, PV; TBARs test) and antioxidant activity (DPPH test) were measured at days 0 and 30 of processing. Freeze-dried samples exhibited higher free acidity (42%) compared to oven-drying (4%), progressively increasing with frozen storage (24% at day 1 vs 51% at day 14). A restricted diet caused up to 60% free acidity. Nevertheless, the FFA profile was similar for both diet conditions, with LA as the major FFA (41% of total FFAs and 27% of total fat). After 30 days of storage, free acidity approached 70%. Oven-drying caused the highest PV (4.5 mEqO2/kg), especially after 14 d of frozen storage (>5.0 mEqO2/kg) and under restricted diet (6.1 mEqO2/kg). Conversely, freeze-drying maintained the lowest PV in all cases (0.6 mEqO2/kg). TBARs values mirrored the PV pattern. Antioxidant capacity was lower for freeze-drying compared to oven-drying (46% and 71%, respectively), regardless of frozen storage. Irrespective of the drying method, worse antioxidant activity was observed after restrictive diet. After 30 days of storage, the antioxidant activity decreased for all samples. The proposed strategy of freezing slaughtering, followed by frozen storage and freeze-drying offers a promising approach to naturally obtain a FLA-rich product from BSFL.

INVESTIGATION OF THE CHEMICAL CHARACTERISTICS AND OXIDATIVE STABILITY OF SOME COMMERCIAL COLD-PRESSED OILS

In this study, the chemical composition and oxidative stability of cold-pressed flaxseed, black seed, pumpkin seed, walnut seed, and poppy seed oils were examined. The results showed that the seed oils contained appreciable amounts of unsaturated fatty acids (above 79 %). Polyunsaturated fatty acids, particularly linoleic acids were dominant, with values ranging from 53.24 % - 71.37 % of the total amount of fatty acids except for pumpkin seed oil. Tocols content was found to be between ~ 490-932 mg kg-1, and the flaxseed oil exhibited the highest levels of total tocopherols (977.47 mg kg-1) under the experimental conditions. While, the highest PV was found in walnut seed oil (2.81 meq O2 kg-1), and the highest content of FFAs was reported for flaxseed oil (1.82 %). OSI values were 4.15, 3.57, 4.31, 3.98 and 4.92 h for the flaxseed, black seed, pumpkin seed, walnut seed, and poppy seed oils, respectively. The obtained data suggest that the seed oils in this study may serve as special dietary sources.

A study on microbial and chemical characterization of mechanically deboned chicken in Tehran, Iran

ABSTRACT This study aimed to investigate microbial, chemical, and heavy metal contamination of mechanically deboned chicken (MDC) in Iran. A total of 24 samples of MDC were obtained from meat plants. TBC of the three samples were acceptable. E. coli and S. aureus were detected in 21 and 6 samples, respectively. Three of the samples were contaminated with Salmonella spp. Campylobacter was not detected in any of the samples. The moisture content of MDC was in the range of 41% to 75%. Ash had a range of 0.74% to 1.4%. The maximum protein content of the MDC was 21.98% and fat content was in the range of 2.1% to 20%. The highest PV was 15.18 mEq/kg. All of the samples were polluted with Pb, Cd, and As. In conclusion, MDC had microbial and chemical contamination. It is necessary to develop more strict criteria for control of the chicken paste processing method.

Behaviour of Distribution Grids with the Highest PV Share Using the Volt/Var Control Chain Strategy

The large-scale integration of rooftop PVs stalls due to the voltage limit violations they provoke, the uncontrolled reactive power flow in the superordinate grids and the information and communications technology (ICT) related challenges that arise in solving the voltage limit violation problem. This paper attempts to solve these issues using the LINK-based holistic architecture, which takes into account the behaviour of the entire power system, including customer plants. It focuses on the analysis of the behaviour of distribution grids with the highest PV share, leading to the determination of the structure of the Volt/var control chain. The voltage limit violations in low voltage grid and the ICT challenge are solved by using concentrated reactive devices at the end of low voltage feeders. Q-Autarkic customer plants relieve grids from the load-related reactive power. The optimal arrangement of the compensation devices is determined by a series of simulations. They are conducted in a common model of medium and low voltage grids. Results show that the best performance is achieved by placing compensation devices at the secondary side of the supplying transformer. The Volt/var control chain consists of two Volt/var secondary controls; one at medium voltage level (which also controls the TSO-DSO reactive power exchange), the other at the customer plant level.

Voltage-matched thin film solar cells in 3-terminal configuration

Multijunction solar cells, proven technological route for achievements of highest PV conversion efficiencies, require accurate tuning of the sub-cell absorption to ensure that every cell in the stack delivers the same current density. Even though currents of the sub-cells can be precisely matched for a fixed illumination spectrum, current mismatch cannot be avoided in real terrestrial applications due to variations of the irradiance spectrum. The issue becomes critical when a solar cell has to cover wider range of applications such as a mixture of direct sun / shadow / artificial light – the case for various distributed PV-powered electronics. Furthermore the current matching constrains choice of materials and designs of sub-cells for a tandem device. A straightforward basic configuration with decoupling the sub-cell's currents is a 3-terminal configuration with one additional contact sheared by the top and bottom cell. This concept requires voltage-matching between the top and bottom cell when these cells are integrated in modules. A realistic concept for the voltage-matched 3-terminal cell reported recently includes a wide gap top cell combined with a tandem bottom cell made of 2 sub-cells with lower bandgaps. The concept is a hybrid between 2 and 3-terminal configurations with voltage matching and relaxed current matching constrains. Established thin film silicon solar cell technology provides interesting option to realize the hybrid 3-terminal cell with amorphous Si top cell (VOC ≈ 0.9 V) and two microcrystalline Si cells (VOC ≈ 0.5 V). In this work we present proof of concept of the voltage matched 3-terminal tandem cell prepared with highly transparent and conductive IOH intermediate contact. The efficiency of 10.4% has been achieved made up of independently operating 7.9% efficient top cell and 2.5% efficient bottom tandem cell. The paper summarizes the development and discusses optical losses identified in the 3-T devices.

Volatile compounds and other indicators of quality for cold‐pressed rapeseed oils obtained from peeled, whole, flaked and roasted seeds

Cold‐pressed rapeseed oil is among the most popular virgin oils. Different processing methods yield oils varying in chemical composition and oxidative stability. The experiment aimed at identifying the differences (mostly in volatiles) between rapeseed oil obtained from peeled seeds (RO) and oils obtained by three pre‐treatment methods: pressing whole seeds (WSO), flakes (FO) and roasted flakes (RFO). Volatiles were analysed using GCxGC‐ToFMS and data were processed using statistical multivariate analysis. Fatty acid composition was determined using GC‐FID. The oils’ oxidative stability was measured using peroxide value. Free fatty acids’ value, absorbance at 236 and 238 nm and chlorophyll content were also determined. Also, a sensory panel evaluation was performed. PCA was found to be effective tool for differentiating the oils on the basis of their volatile compounds. RO was most similar to WSO from the second pressing. Fatty acid composition analysis yielded differences between the experimental oils and RO. RO had the highest PV, p‐AV and Totox values. WSO from the first pressing (WSO1) had the highest oxidative stability. Sensory analysis found that WSO1 was most similar to RO. Both oils had an intense cabbage‐like and fruity odour. The study showed that the results of volatile compounds’ analysis differs from those of sensory analysis in oils comparison.Practical applications: The results demonstrate that the rapeseed oil obtained from whole seeds may have a volatile compounds composition that is similar to that of rapeseed oil obtained from peeled seeds. PCA makes it possible to differentiate between samples varying in pre‐treatment method as well as between samples subjected to the same pre‐treatment method, but obtained from a second pressing. Sensory panel performed by trained panellists may demonstrate which oils are most desirable when rated for selected attributes. The results of sensory panel may differ from those of volatile compound analysis performed with GCxGC‐ToFMS.In the current study, the volatile compounds in cold‐pressed rapeseeds oil obtained from peeled seeds with those in rapeseed oils obtained from seeds prepared with various pre‐treatment methods are compared. The obtained results are compared with those of sensory evaluation. The study shows that the results obtained by means of statistical analysis based on volatile compounds do not always correlate with those of sensory panel evaluation in oils comparison.

Fatty acid profile of new promising unconventional plant oils for cosmetic use

Oils have been used on the cosmetic application since antiquity. With the growing interest in cosmetic formulation of strictly natural origin there has been also an increased interest in the use of alternative oils obtained from nuts, herbs, fruit and vegetable seeds. Due to lack of good scientific reports on the cosmetic plant oils available in Poland, the aim of our research was to characterize fatty acids (FA) profile and oxidative quality of selected unconventional plant oils, which are used as cosmetics or potential cosmetic ingredients. Oils were purchased from cosmetic health shops in Warsaw (Poland); FA profile was analysed by gas chromatography with flame-ionization detection. Peroxide index (PI), content of hydroperoxides (PV) and free fatty acids (AV) were also determined. Oxidative quality and FA composition of examined oils varied widely among analyzed oils. Cluster analysis revealed three clusters. Clusters S1 and S3 include only one oil (Perilla and sea buckthorn, respectively). Perilla oil is characterized by relatively small content of both saturated FA (8.5%) and monounsaturated FA (14.2%) and much higher amount of polyunsaturated FA (73.5%) whereas in sea buckthorn these proportions are opposite (saturated FA and monounsaturated FA - 33.5% and 51.0% respectively, and the lowest amount of polyunsaturated FA - 5.2%). In cluster S2 two sub-clusters were distinguished and the content of linoleic (p = 0.0015), α-linolenic (p = 0.0092) and oleic (p = 0.0015) acid caused this distinction. PI ranged from 8.9 in sea buckthorn oil to 135 in Perilla oil. Perilla oil and raspberry seed oil were also characterized by the highest PV (225 ± 14.9 mEq O/kg oil and 232 ± 13.8 mEq O/kg oil, respectively), whereas the lowest PV was determined for walnut oil (0.82 ± 0.18 mEq O/kg oil) and carrot seed oil (0.87 ± 0.21 mEq O/kg oil) oils. FA composition of cosmetic oils in combination with data concerning their oxidative quality, is very important for determining their safe and effective use. It is very important to standardize and test the FA content in commercially available oils of cosmetic use.

EXPOSURE TIME ON BACTERIA FLORA/COUNT AND SHELF LIFE OF CANNED SARDINE (SARDINELLA PILCHARDUS) UNDER AMBIENT AND COLD STORAGE CONDITIONS

This study is aimed at investigating the exposure time on bacteria flora/count and shelf life of conned sardine (Sardinella pilchardus) under ambient and cold storage conditions. Twenty-five cans with an average weight of 165.05 g of the Titus (with an expiration date of 4 years (September 30, 2004 to September 30, 2008 of batch no. 1432) were purchased and stored at the ambient temperature of 27C and cold (−4C) storage conditions as samples for 12 weeks (precisely between June 15 and September 10, 2005 when the experiment lasted). Proximate analysis of the samples was taken at the beginning of the experiment and at the end for both the ambient and cold stored (after an exposure time of 24 h). Initial baseline and biweekly studies were carried out for 12 weeks for: (1) organoleptic (odor, taste, texture, appearance, rigidity of flesh, color and reaction of fish with can); (2) chemical (trimethylamine [TMA], peroxide values [PVs] and thiobarbituric acid [TBA]); and lastly (3) microbiological analysis for bacteria count and identification of the bacteria on the samples from each storage environment after an exposure time of 24 h in each case. All the chemical parameters (TMA, TBA and PV) were significantly (P < 0.05) correlated with exposure/storage time. Correlation coefficients r = 0.60, 0.66 and 0.54 were low in all classes therefore indicating spoilage rate increases slightly with exposure time/storage period. The highest PV (0.023–0.715), TBA (0.057–1.056) and TMA (1.01 × 103–3.63 × 103) ranges were recorded for canned sardines stored at ambient temperature of 27C. However, these are still within acceptable tolerance limit (i.e., organoleptic score of 4–7). Organoleptic assessment with average scores of 5.5 and 6.0 was recorded for cold and ambient stored samples. No viable bacteria count was recorded for cold-stored samples throughout the experiment. However, the range initial 1.0 × 105 and final 5.0 × 104 cfu/g total plate counts recorded for ambient storage were still below the minimum bacteria count for spoilage that could cause significant or deleterious effect that could result in food poisoning. Traces of the following bacterial species were recorded at ambient temperatures: (1) Bacillus subtilis (1.2 × 104 cfu/g); (2) Streptococcus faecium (9.0 × 103 cfu/g); (3) Proteus vulgaricus (7.0 × 105 cfu/g); (4) Pediococcus halophilus (6.0 × 105 cfu/g); (5) Micrococcus acidophilus (4.0 × 103 cfu/g); (6) Streptococcus lactis (4.0 × 103 cfu/g); and (7) Aerobacter aerogenes (4.0 × 103 cfu/g), while fungal species Aspergillus terreus (1.0 × 103 cfu/g) and Aspergillus niger (3.0 × 103 cfu/g) were recorded also for samples stored at ambient temperature of 27C. Hence, in view of this, the 4-year recommended expiration date may be upheld for canned sardine (S. pilchardus fish products in oil sources) provided the hazard analysis and critical control points, and closely monitored. It is, therefore, recommended that exposure of canned sardine in oil should not exceed 12–24 h under whatever food storage temperatures to avoid food poisoning.

Predictive values of waist circumference for dyslipidemia, type 2 diabetes and hypertension in overweight White, Black, and Hispanic American adults

Waist circumferences (WC) ⩾102 cm for men and ⩾88 cm for women have been proposed by an expert panel as cut-points for identifying increased risk for the development of obesity comorbidities for most adults. The aim of this investigation was to examine the predictive values of these WC cut-points for hypercholesterolemia, low concentration of high (HDL-C), and high concentration of low (LDL-C) density lipoprotein cholesterol, hypertriglyceridemia, type 2 diabetes, and hypertension in overweight American adults. Data from NHANES III were utilized for the analysis. Predictive abilities were determined by calculating sensitivity, specificity, positive (PV+) and negative (PV−) predictive values in overweight subjects with BMI 25–29.9 kg/m 2. Sensitivity of WC cut-point was stronger for high LDL-C compared to other risk factors with the highest values recorded in the 40–59 and 60–69 year age groups in men and women, respectively. PV+ of WC cut-points for dyslipidemia, type 2 diabetes, and hypertension were low in men compared to women. PV+ tended to increase with age, from 19–39, 40–59 to 60–90 year age groups in Whites, Blacks, and Hispanic men. In men, the highest PV+ were recorded for hypertriglyceridemia in the 60–90 years old groups, with values of 71.6%, 52.5%, and 43.3% in Whites, Blacks, and Hispanics, respectively. The CVD risk factor associated with the highest PV+ in women was diabetes with values of 97.2% in Whites and 88.9% in Blacks, and hypertriglyceridemia with a value of 93.8% in the 17–39 year age group in Hispanics. Among Black men 40–59 years of age, only 32% of a population of overweight hypertensives were detected by the WC cut-points, and among Black women, 40–59 years of age, only 54% were detected. Given the low sensitivity of these cut-points for detecting hypertension, one of the major co-morbidities of obesity, these cut-points failed to provide adequate evidence for the use of WC in determining or evaluating patients as to co-morbid states. We recommend further studies to determine a set of specific cut-points associated with increased risk of CVD in different population groups.

Diagnostic value of signs and symptoms associated with peripheral arterial occlusive disease seen in general practice: a multivariable approach.

To assess the diagnostic values of single and combined data from the history, physical examination, and medical record with regard to peripheral arterial occlusive disease (PAOD) in patients with leg complaints; to construct a multivariable model for the clinical diagnosis of PAOD by primary care physicians. 18 general practice centers in The Netherlands. Cross-sectional comparison of signs, symptoms, and data from the medical record with the independently assessed ankle-brachial systolic pressure index (ABPI; cutoff point < 0.90); analysis: bivariate, multiple logistic regression (MLR). 2,455 individuals with leg complaints, aged 40.7-78.4 years; ABPI < 0.90 present in 9.2% of legs (11.7% of individuals). Clinical variables: sensitivity, specificity, positive and negative predictive values (PV+, PV-), diagnostic odds ratio (OR); models: likelihood ratio test, area under the receiver operating characteristic curve (AUC). Bivariate analysis: highest sensitivity: age more than 60 years (77.3%); highest specificity: wounds or sores on toes and foot (99.7%); highest PV+: typical intermittent claudication (IC) (45.0%) (abnormal foot pulses 41.3%); highest PV-: strong pulses of both foot arteries (97.7%). MRL: the best-performing model (AUC 0.89) consisted of ten clinical variables: gender (OR 1.5), age more than 60 (OR 2.2); IC (OR 3.5); palpation of the skin temperature of the feet (OR 2.5), palpation of both foot pulses [OR 16.4 (abnormal) and 7.0 (doubtful)], auscultation of the femoral artery (OR 3.5); previous diagnosis of IHD (OR 1.7) or diabetes (OR 1.6), history of smoking (OR 2.1), and elevated blood pressure (OR 1.5). The range of predicted probabilities was 0.4-98%. The Hosmer-Lemeshow goodness-of-fit test indicated good overall fit (p = 52). Palpation of both foot pulses is the key procedure for the clinical diagnosis of PAOD. Traditional clinical evaluation enables the general practitioner to exclude the diagnosis of PAOD in many individuals with a high degree of certainly, to establish the diagnosis in a small group of patients, and to define a limited group of patients where supplementary noninvasive testing is appropriate. The MLR model can be used as a diagnostic checklist and as a reference for the physician's clinical hypothesis.