| 1. |
- Cassi, Xavier Fernandez, et al.
(författare)
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Microbial communities and Food safety aspects of crickets (Acheta domestica) reared under controlled conditions
- 2020
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Ingår i: Journal of insects as food and feed. - 2352-4588. ; 6, s. 429-440
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Tidskriftsartikel (refereegranskat)abstract
- In an approach combining microbiological culture methods with high-throughput sequencing, this study investigated the microbial communities (bacteria, moulds and yeasts) in Swedish-produced edible crickets (Acheta domesticus) reared in a controlled environment. The effects of different feeds on microbial loads and populations in crickets were also studied. The crickets used were third-generation offspring from wild-caught individuals from Sweden, which are adapted to grow in a laboratory environment. The efficiency of rinsing to decrease microbial load was evaluated not obtaining a significant decrease of plating counts for total aerobic counts (TAC) and Enterobacteriaceae. Crickets were divided into three batches and fed different diets (control feed, early-cut red clover hay (ECH), late-cut fresh red clover (LCF)) for 62 days. Bacterial numbers (TAC and Enterobacteriaceae) on whole raw crickets ranged between 7 and 8 log cfu/g. Pre-rinsing in water did not reduce these levels (P=0.19). All batches tested negative for the food-borne bacteria Salmonella, Listeria monocytogenes, Bacillus cereus and Clostridium perfringens. The mean mould count for crickets fed control feed was 2.8 log cfu/g, while the values for crickets fed ECH and LCF were 4.2 and 4.5 log cfu/g, respectively. The dominant bacterial communities were Proteobacteria, Bacteroidetes and Firmicutes, with Firmicutes and Proteobacteria dominating in crickets fed control feed, Firmicutes dominating in crickets fed LCF and Proteobacteria dominating in crickets fed ECH. Aspergillus flavus, a fungus that is capable of producing mycotoxins, was detected in control feed and ECH reared crickets. More work is needed to identify specific food-borne pathogens in edible crickets and establish possible bacterial quality reference values, as an important step in developing microbial quality and safety parameters to ensure consumer safety.
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| 2. |
- Cassi, Xavier Fernandez, et al.
(författare)
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The house cricket (Acheta domesticus) as a novel food: a risk profile
- 2019
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Ingår i: Journal of insects as food and feed. - 2352-4588. ; 5, s. 137-157
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Forskningsöversikt (refereegranskat)abstract
- Novel foods represent sustainable alternatives to traditional farming and conventional foodstuffs. The house cricket (Acheta domesticus) is considered as one of the most promising reared insects due to their attractive nutritional profile and lower feed conversion ratio compared to other animals. However, putative health hazards associated with consumption of crickets have previously not been investigated. The present study assesses the risks of A. domesticus reared in closed systems controlled by the implementation of hazard analysis and critical control points and good farming practices. Due to the novelty of the topic, data scarcity has been a limiting factor, hence comparative evidence from closely related species belonging to the order Orthoptera (e.g. grasshoppers, locusts, and other cricket species) have been included. The present risk profile identified as main hazards: (1) high total counts of aerobic bacteria; (2) presence of spore-forming bacteria post thermal processing; (3) accumulation of cadmium and other heavy metals; and (4) a possible increase of allergenic reactions due to exposure to insects and insect derived products. Important data gaps regarding edible crickets and their safety as novel foods have been highlighted in the future perspective section, representing aims for future research. Identified data gaps include: (1) farming conditions of the insects being studied; (2) data on the impact of thermal processing of the products prior to consumption; (3) fungal communities and mycotoxins-producing fungi in reared crickets; and (4) heavy metals not fully assessed (chromium, aluminium and arsenic) and other chemical hazards produced during processing (i.e. heterocyclic aromatic amines, acrylamide). The present risk profile explores food safety risks related to consumption of A. domesticus, thereby constituting an example of chemical and microbial hazards risk profiling on edible insects, covering rearing to consumption.
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| 3. |
- Cholleti, Harindranath, et al.
(författare)
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House crickets (Othroptera: Gryllidae: Acheta domesticus) reared in small-scale laboratory conditions harbour limited viral flora
- 2022
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Ingår i: Journal of insects as food and feed. - 2352-4588. ; 8, s. 1149-1155
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Tidskriftsartikel (refereegranskat)abstract
- Insects, such as crickets, are being used as a viable food source in many regions of the world, given their nutritional value for human and animal consumption. This study investigated the viral communities present in European house crickets and whether feed influences the composition of the crickets’ virome. The crickets were reared under environmentally controlled conditions and fed fresh red clover (fresh), red clover haylage (haylage), red clover hay (hay) or control feed. The viral metagenomic analysis of six replicates from each feed treatment showed that only a few reads were classified as viruses, mainly assigned to phages and insect-related viruses. A significant difference (P<0.001) was observed between the different treatments in regard to the number of viral reads. The highest number of viral reads was identified in the fresh treatment (2,568 reads), whereas the control treatment had the fewest viral reads (90). Phages were identified in all the treatments; however, they were clearly dominant in the fresh and hay feed treatments. A limited number of insect and plant viral reads from Xinmoviridae, Polydnaviridae, Metaviridae, unclassified and ‘other’ viruses were also found in all the feed treatments. The results from this study may indicate that the feed for the crickets determines the richness of the viral flora of crickets, but overall, very few viral reads were identified, making it hard to draw any conclusion regarding the impact of the feed on viral richness.
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| 4. |
- Gidlund, Helena, et al.
(författare)
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Predicting omasal flow of nonammonia N and milk protein yield from in vitro-determined utilizable crude protein at the duodenum
- 2018
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Ingår i: Journal of Dairy Science. - : American Dairy Science Association. - 0022-0302 .- 1525-3198. ; 101, s. 1164-1176
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Tidskriftsartikel (refereegranskat)abstract
- This study evaluated the relationship between utilizable crude protein (uCP) at the duodenum estimated in vitro and omasal flow of crude protein (CP; omasal flow of nonammonia N x 6.25) measured in lactating dairy cows. In vivo data were obtained from previous studies estimating omasal digesta flow using a triple-marker method and N-15 as microbial marker. A total of 34 different diets based on grass and red clover silages were incubated with buffered rumen fluid previously preincubated with carbohydrates for 3 h. The buffer solution was modified to contain 38 g of NaHCO3 and 1 g of (NH4) HCO3 in 1,000 mL of distilled water. Continuous sampling of the liquid phase for determination of ammonia-N was performed at 0.5, 4, 8, 12, 24, and 30 h after the start of incubation. The ammonia N concentrations after incubation were used to calculate uCP. The natural logarithm of uCP [g/kg of dry matter (DM)] at time points 0.5, 4, 8, 12, 24, and 30 h of incubation was plotted against time to estimate the concentration of uCP (g/kg of DM) at time points 16, 20, and 24 h using an exponential function. Fixed model regression analysis and mixed model regression analysis with random study effect were used to evaluate the relationships between predicted uCP (supply and concentration) and observed omasal CP flow and milk protein yield. Residual analysis was also conducted to evaluate whether any dietary factors influenced the relationships. The in vitro uCP method ranked the diets accurately in terms of total omasal CP flow (kg/d) or omasal CP flow per kilogram of DM intake. We also noted a close relationship between estimated uCP supply and adjusted omasal CP flow, as demonstrated by a coefficient of determination of 0.87, although the slope of 0.77 indicated that estimated uCP supply (kg/d) was greater than the value determined in vivo. The linear bias with mixed model analysis indicated that uCP supply overestimated the difference in omasal CP flow between the diets within a study, an error most likely related to study differences in feed intake, animals, and methodology. Predicting milk protein yield from uCP supply showed a positive relationship using a mixed model (coefficient of determination = 0.79), and we observed no difference in model fit between the time points of incubation (16, 20, or 24 h). The results of this study indicate that the in vitro method can be a useful tool in evaluating protein value of ruminant diets.
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| 5. |
- Inacio, Ana Carolina, et al.
(författare)
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Impact of starvation on fat content and microbial load in edible crickets (Acheta domesticus)
- 2021
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Ingår i: Journal of insects as food and feed. - 2352-4588. ; 7, s. 1143-1147
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Tidskriftsartikel (refereegranskat)abstract
- Interest in insects as food is increasing worldwide, particularly in industrialised countries. Insect-based ingredients are considered novel foods in Europe and there are unresolved concerns regarding food safety. Microbial counts in insects can be high, posing potential health risks to consumers and possibly causing rapid deterioration by spoilage microorganisms. Gut emptying by starvation prior to killing could reduce the microbial load in the insect gut but could also lead to fat loss and lower energy content, reducing the profitability of production. This study evaluated the microbial load (total aerobic counts (TAC), Enterobacteriaceae) in house crickets (Acheta domesticus) starved for 0 h (control), 24 h, and 48 h, and the corresponding fat losses. The 24 h starvation group showed significantly lower (P=0.004) Enterobacteriaceae counts of one log cfu/g, but not TAC, (compared to the control group). TAC was significantly increased (P=0.002), by almost one log cfu/g in the 48 h starvation group compared with the control. Sex of the insects had no significant effect on microbial numbers (P=0.72 and P=0.46 for TAC and Enterobacteriaceae, respectively). Starvation for 24 h decreased fat content in crickets (P=0.02), indicating potential production losses. This shows that starvation is not an effective method for reducing microbial loads in edible crickets.
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| 6. |
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| 7. |
- Krizsan, Sophie Julie, et al.
(författare)
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An in vitro evaluation of browser and grazer fermentation efficiency and microbiota using European moose spring and summer foods
- 2018
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 8, s. 4183-4196
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Tidskriftsartikel (refereegranskat)abstract
- Evolutionary morphological and physiological differences between browsers and grazers contribute to species- specific digestion efficiency of food resources. Rumen microbial community structure of browsers is supposedly adapted to characteristic nutrient composition of the diet source. If this assumption is correct, domesticated ruminants, or grazers, are poor model animals for assessing the nutritional value of food consumed by browsing game species. In this study, typical spring and summer foods of the European moose (Alces alces) were combined with rumen fluid collected from both dairy cows (Bos taurus) and from moose, with the aim of comparing fer- mentation efficiency and microbial community composition. The nutritional value of the food resources was characterized by chemical analysis and advanced in vitro measurements. The study also addressed whether or not feed evaluation based on in vitro techniques with cattle rumen fluid as inoculum could be a practical alternative when evaluating the nutritional value of plants consumed by wild browsers. Our re- sults suggest that the fermentation characteristics of moose spring and summer food are partly host- specific and related to the contribution of the bacterial phyla Firmicutes and Bacteriodetes to the rumen microbial community. Host- specific adaptations of the ruminal microbial community structure could be explained from the evolutionary adaptations related to feeding habitats and morphophysiological differences be- tween browsers and grazers. However, the observed overall differences in microbial community structure could not be related to ruminal digestion parameters measured in vitro. The in vitro evaluation of digestion efficiency reveals that equal amounts of methane were produced across all feed samples regardless of whether the ruminal fluid was from moose or dairy cow. The results of this study suggested that the nutri- tional value of browsers’ spring and summer food can be predicted using rumen fluid from domesticated grazers as inoculum in in vitro assessments of extent of digestion when excluding samples of the white water lily root, but not of fermentation characteristics as indicated by the proportions of individual fermentation fatty acids to the total of volatile fatty acids.
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| 8. |
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| 9. |
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| 10. |
- Thorsson, Elina, et al.
(författare)
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Histochemical localisation of carbonic anhydrase in the digestive tract and salivary glands of the house cricket, Acheta domesticus
- 2020
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Ingår i: Journal of insects as food and feed. - 2352-4588. ; 6, s. 191-198
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Tidskriftsartikel (refereegranskat)abstract
- The house cricket (Acheta domesticus) is one of several cricket species with great potential to be farmed as a sustainable protein source. In order to succeed in large-scale cricket farming, knowledge of cricket digestion is essential. The digestive tract morphology of A. domesticus is well documented, but knowledge of the salivary glands is lacking. In the digestive tract of insects, the carbonic anhydrase (CA) enzyme family is believed to contribute to the luminal pH gradient. Presence of CA in the digestive tract of A. domesticus has been reported, but not the cellular localisation. This study examined the digestive tract of A. domesticus, including salivary glands, and the cellular localisation and activity of CA in fed or starved (48 h) males and females. Tissues were collected from third-generation offspring of wild A. domesticus captured in Sweden and the histology of the salivary glands and the cellular localisation of CA in the digestive tract of A. domesticus were determined, to our knowledge for the first time. The salivary glands resembled those of grasshoppers and locusts, and we suggest the two main cell types present to be parietal and zymogenic cells. Histochemical analysis revealed that CA activity was localised in midgut epithelium, both main cell types of salivary gland, and muscle along the entire digestive tract. These findings support the suggestion that CA contributes to digestive tract luminal pH gradient, by driving acidic secretions from the salivary glands and alkaline secretions from the midgut. Starvation resulted in significantly reduced body size and weight, but neither starvation nor sex had any effect on CA activity or localisation.
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