Effects of Drying Methods on the Biochemical Composition and Organoleptic Properties of Two Freshwater Fish Species (Mormyrus rume and Labeo coubie) of Cross River Obubra, Nigeria

Consumers all over the world are increasingly becoming aware of the health and nutrition status of fish and fishery products. There have develop some preference for fish species and even their processing methods. This study aims to investigate the effects of two drying methods (smoking and oven drying) on the biochemical components and organoleptic properties of two less preferred food fishes abundant in the study area. The fish samples Mormyrus rume and Labeo coubie were purchased from fresh landings of fishermen at Ahaha beach. The biochemical assay of the moisture, protein, fat, carbohydrate, ash, calcium (Ca), magnesium (Mg), phosphorus (P), iron (Fe), sodium (Na) and potassium (K) were conducted in the labouratory using standard methods. The proximate composition of raw M. rume was determined as moisture 70.38%, protein 17.43%, carbohydrate 1.13%, fat 5.93% and ash 2.77% while oven dried were 18.78, 63.85, 3.37, 8.73 and 7.58% respectively. All the proximate parameters and gross energy level investigated were higher (p < 0.05) in M. rume except the moisture content of dried samples of L. coubie. The mineral content were in the order Ca < Mg < Fe < Na < P and < K in both species and were higher in M. rume except Na. The drying methods showed increase in the proximate and mineral compositions in the order raw < smoking and < oven drying except moisture content that decreased respectively is both species. Organoleptic properties revealed that dried samples (smoked and oven) were not significantly different (p < 0.05) in taste, flavour, texture and overall acceptance, however while oven dried had better colour (4.33), smoked dried taste (4.63) better. The drying methods shows concentration of the required nutrients in human diets and were also found to be most palatable by the panellist. To improve fish nutrient quality smoke and oven drying should be encourage.

2020 ◽  
Vol 24 (6) ◽  
pp. 1085-2020
Author(s):  
K.M. Adamu ◽  
H. Muhammad ◽  
S.U. Ahmad ◽  
M.M. Ahmad ◽  
A.M. Yakubu

Understudying the presence of bacteria and fungi population on freshwater fishes, provides the knowledge and understanding of their diversity and potential roles they may play in the health of the aquatic and terrestrial ecosystems. The present study was conducted to evaluate the diversity of bacteria and fungi species of identified fish samples from River Mijawal, Nasarawa State. The fishes were sampled from the only landing for three months (October to December, 2019) for this study. During the sampling periods, thirteen (13) different fish species were identified; they were  swabbed with sterilized swab stick from the skin surface for bacteria and fungi identification. The Dominant fish species were Tilapia zillii, Labeo senegalensis, Mormyrus rume and Mormyrus tapines. The total number of thirteen (13) bacterial and five (5) fungi species were isolated and  identified. Eight (8) of the bacteria isolates, were gram negative bacteria (Pseudomonas sp, Aeromonas sp, Serratia mercescenes, Proteus sp, Salmonella spp, Escherichia coli, Klebsiella sp, and Enterobacter sp.); whilst the other five (5) were gram positive bacteria (Bacillus sp, Micrococcus sp, Staphylococcus sp, Enterococcus sp and Listeria monocytogenes).The five isolated fungi species were Aspergillus niger, Rhizopus sp, Penicillium  sp, Trichoderma viridae and Geotrichum candidum. The frequency of occurrence of the isolated bacteria indicated that Staphylococcus sp had the highest frequency of occurrence (16.67%) while Serratia mercescens had the least occurrence (2.78%). The highest number of occurrence of the isolated fungi species was observed in Rhizopus sp while the least was recorded in Geotricum candidum. It was observed that Tilapia zillii and  Mormyrus rume had the most frequent bacteria and fungi isolates. It can therefore be deduced from the results that fish samples identified from River Mijawal has high bacteria and fungi diversity that may be pathogenic to man. The occurrence of these microbes may be attributed of human  and animal faeces in the River  Keywords: Freshwater fishes, Microbes, River Mijawal, Nasarawa  


Author(s):  
Sonia Singh ◽  
Neetu Agrawal

The herbs, Chenopodium album Linn. and Spinacia oleracea Linn. belongs to Chenopodiaceae family, are the two nutritious and edible green leafy food crops, abundantly found especially in the northern-west region of India. These plants have gained renown popularity, because of their high nutritional content including protein, amino acids, carbohydrate, and even the presence of phenolic components, which ultimately may get affected with drying and storage techniques. Impact of different drying methods (microwave drying at 4 minutes, hot air oven drying at 5 hours and sun drying at 8-10 hours) on nutrient quality and antioxidant property of Chenopodium album Linn. and Spinacia oleracea Linn. leaves were evaluated by using UV spectrophotometritc assay, total phenolic content and DPPH free radical scavenger method. Drying treatments were significantly decreased the moisture, carbohydrate and protein content present in C.album and S. oleracea. Hot air oven drying method produced dried samples of C.album and S. oleracea had significantly similar antioxidant activity when compared with the samples obtained from sun drying method. The dried samples obtained from hot air oven drying technique showed significant presence of total phenolic content in C. album and S. oleracea (6.44±0.12 mg/g, 6.69±0.40 mg/g) whilst the traditional sun drying method produced 8.00±0.02 mg/g and 7.89±0.37 mg/g). It is concluded that microwave drying and hot air oven drying were the methods to preserve appreciable percentage of nutrient components compared to the fresh samples. On other hand, the traditional method produced substantial reduction of nutrient quality. From statistical analysis, hot air oven drying technique was considered as optimum method which showed satisfactory % retention of protein (65.86%) and carbohydrate (85.95%) at 5 hours (shorter time than sun drying time period) along with significant antioxidant activity (34.89 μg/mL and 35.60 μg/mL) similar as obtained from the traditional technique (32.00 μg/mL).


2018 ◽  
Vol 82 (1) ◽  
pp. 151-158 ◽  
Author(s):  
YOUNG MI KANG ◽  
MIN JOO KIM ◽  
SUN YOUNG PARK ◽  
MIN SOO HEU ◽  
JIN-SOO KIM

ABSTRACTBecause of the increased awareness of the health benefits of fish, fish consumption has increased each year in several countries, including Korea. However, fish consumption is associated with acute toxicity owing to the presence of biogenic amines in rapidly spoiling fish. Several food safety agencies have established standards for acceptable histamine concentrations in some restrictive fish and fishery products; however, such standards are not available for other species. We aimed to generate data from biogenic amine monitoring to evaluate the safety of fish commonly consumed in Korea. We monitored the biogenic amine concentrations in 609 fish samples from 19 commonly consumed species. Of these 609 samples, several had amine concentrations higher than the maximums allowed. An age-specific exposure assessment based on human biogenic amine exposure per serving revealed that persons 1 to 3 years of age had the highest exposure to total biogenic amines, although no significant differences were found between the age groups analyzed. The analysis also revealed that the exposure in some fish species, such as Japanese jack mackerel, Konoshiro gizzard shad, and brown sole, exceeded the standard limits established in some countries. These results suggest that more fish species should be included to establish standards for exposure to various biogenic amines. Parameters such as age-specific consumption and data for populations with maximum consumption should be considered because the current standards are limited to histamine and do not account for the differences in histamine sensitivity associated with these variables. Our results provide important data on limits for biogenic amines in various fish species that could be used to minimize potential health risks.


Insects ◽  
2019 ◽  
Vol 10 (4) ◽  
pp. 84 ◽  
Author(s):  
Nina Kröncke ◽  
Sandra Grebenteuch ◽  
Claudia Keil ◽  
Sebastian Demtröder ◽  
Lothar Kroh ◽  
...  

Yellow mealworm (Tenebrio molitor L.) represents a sustainable source of proteins and fatty acids for feed and food. Industrial production of mealworms necessitates optimized processing techniques, where drying as the first postharvest procedure is of utmost importance for the quality of the final product. This study examines the nutritional quality of mealworm larvae processed by rack oven drying, vacuum drying or freeze drying, respectively. Proximate composition and fatty acid profile were comparable between the dried larvae. In contrast, larvae color impressions and volatile compound profiles were very much dependent on processing procedure. High-temperature rack oven drying caused pronounced darkening with rather low content of volatiles, pointing toward the progress of Maillard reaction. On the other hand, vacuum drying or freeze drying led to enrichment of volatile Maillard reaction and lipid oxidation intermediates, whose actual sensory relevance needs to be clarified in the future. Beyond sensory and visual importance drying intermediates have to be considered with regard to their metal ion chelating ability; in particular for essential trace elements such as Zn2+. This study found comparable total zinc contents for the differently dried mealworm samples. However, dried larvae, in particular after rack oven drying, had only low zinc accessibility, which was between 20% and 40%. Therefore, bioaccessibility rather than total zinc has to be considered when their contribution to meeting the nutritional requirements for zinc in humans and animals is evaluated.


2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
A. J. Nyantakyi ◽  
S. Wiafe ◽  
O. Akoto ◽  
Bernard Fei-Baffoe

Appreciable levels of trace metals have been reported in the Tano basin, but data on the corresponding levels in fish and the risk they pose to consumers are limited. The levels of 7 trace metals in 18 fish muscles were assessed between November 2016 and October 2017 using acid digestion and PerkinElmer (PinAACle 900T) Atomic Absorption Spectrophotometry. Apart from Cu, all the metals studied were detected in all fish samples. The levels of Cr, As, and Hg were higher than the acceptable levels of fish muscles. Cr concentration ranged from 16.10 ± 0.2 mg/kg in Clarias gariepinus to 57.9 ± 4.2 mg/kg in Sarotherodon galilaeus. The levels of As ranged from 1.01 ± 0.08 in Clarias gariepinus to 3.00 ± 0.01 mg/kg in Mormyrus rume. Hg level was 0.58 ± 0.69 mg/kg in Oreochromis niloticus and 2.52 ± 0.70 mg/kg in Ctenopoma kingsleyae. However, Pb, Zn, and Cd concentrations were below the Food and Agriculture Organization limits with low target hazard quotients in all fish samples, suggesting no possible noncarcinogenic risks to adult consumers. Possible noncarcinogenic and carcinogenic health risks were recorded for As, Hg, and Cr in all fish species. Strong associations were observed between Hg, As, Zn, and Cr and between Pb and Cd suggesting a possible common source. Mormyrus rume fish species was under stress in the river, but the remaining species were in good condition. Periodic monitoring of trace metal concentrations in fish and enforcement of the buffer zone policy are recommended.


Molecules ◽  
2021 ◽  
Vol 26 (20) ◽  
pp. 6260
Author(s):  
Nurul Hanisah Juhari ◽  
Helle Jakobe Martens ◽  
Mikael Agerlin Petersen

Fresh roselle are high in moisture and deteriorate easily, which makes drying important for extending shelf-life and increasing availability. This study investigated the influence of different drying methods (oven-drying, freeze-drying, vacuum-drying, and sun-drying) on the quality of roselle calyx expressed as physicochemical properties (moisture content, water activity, soluble solids, color), volatile compounds, and microstructure. Oven-drying and freeze-drying reduced moisture content most while vacuum-drying and sun-drying were not as efficient. All drying methods except sun-drying resulted in water activities low enough to ensure safety and quality. Vacuum-drying had no impact on color of the dry calyx and only small impact on color of water extract of calyx. Drying reduced terpenes, aldehydes, and esters but increased furans. This is expected to reduce fruity, floral, spicy, and green odors and increase caramel-like aroma. Sun-drying produced more ketones, alcohols, and esters. Scanning electron microscopy revealed that freeze-drying preserved the cell structure better, and freeze-dried samples resembled fresh samples most compared to other drying techniques. The study concludes that freeze-drying should be considered as a suitable drying method, especially with respect to preservation of structure.


2021 ◽  
Vol 1195 (1) ◽  
pp. 012002
Author(s):  
L O Morris ◽  
C M Chu ◽  
E Suali

Abstract This work focuses on the lipid yield of algae dried using an enhanced solar chimney dryer with the aim towards high quality biodiesel production and low energy consumption. Jaworski’s medium was chosen for the cultivation in this research project as it can provide enough nutrients to green algae of type Chlorella. Sp. Centrifugation is an effective method to harvest the algae from its medium prior to a drying process. In this project, the methods used for drying were oven drying, open-sun drying and an enhanced solar chimney drying. The moisture content was determined where the average moisture content were 82.5% for oven drying method, 81.6% for open sun drying and 82.2% for solar chimney drying. Methods were found to affect differently the algae properties in terms of the lipid yield and mineral content. The lipid yields were 23.7%, for oven drying, 20.6% for open sun drying and 24.4% for enhanced solar chimney drying. While the oven drying was found to be the fastest way to dry the algae, the solar chimney drying proved best in energy saving while producing the same amount or more algae lipid within reasonable drying times.


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