title: Rendering koi carp and creating economic value by making pet food

authors: Wei, Jiaoying

subjects: rendering

abstract: Koi carp is an invasive species fish in New Zealand that severely destroys the aquatic environment in the waterways in the Waikato region. The aim of the project was to look for a method that could make use of captured koi carp. Wet rendering and autoclave rendering was examined for producing fish meal and oil under different processing conditions such as time, temperature and water content.
The water content of raw minced fish was around 69-77%, the solids content was between 23%-31%. Ash content was 6.2-7.4% of the dry solids and fat content between 13.7%-30%. Fish with a high fat content were females containing roe. The meal produced from wet rendering contained 22-28% solids, with 5-9% ash and 14-16% fat on a dry basis, while the stickwater contained 3% solids and 12-39% ash on a dry basis. Autoclave rendering produced a meal containing 26-30% solids, 3-5% ash and 30-31% fat on a dry basis and a stickwater containing 3.2% solids and 27-32% ash on a dry basis. Fat reduction in meal increased with rendering time for wet rendering up to 30% at 40 minutes rendering time, while only a 20% reduction in fat was achieved for autoclave rendering. Wet rendering was selected for producing meals.
Dry pet food and wet pet food was made by mixing rendered fish meal with chicken mince. The dry food was produced by baked while the wet food was produced by steaming. Taste testing showed that cats preferred wet pet food over the dry pet food. The dry pet food had a strong odour and poor palatability. Most cats in the taste testing hesitated to try or eat much of the dry food. It was hard for them to chew the nibbles. Less koi carp meal should be used to improve palatability. The majority of the wet pet food was consumed and it had a better odour.
A customer survey showed acceptance of koi carp for pet food was high. 92% of the participants felt they would buy or try later. People who have pets were more open-minded about using pet food made from koi carp.
An economic analysis showed that 165 tonnes of koi carp could be harvested per year from four Waikato lakes by Huntly, maintaining a biomass density of 140 kg/hectare, down from the current average density of around 200 kg/hectare. To reduce the density down to 100 kg/hectare, koi carp would need to be harvested at 205 tonnes per year for the first 12 years, reducing harvesting to 170 tonnes per after this. Wet pet food production is much more profitable than dry pet food production. The price of each 100 g can of wet pet food to break even should be around $1.7 which is comparable to supermarket prices. This is approximately 10 times the price of dry pet food on a per kg basis. The profit made at $2 per can at 165 tonnes of fish per year is $408K while at 205 tonnes of koi carp the profit is $526K. Dry pet food needs to be sold at just under $6 per kg to breakeven at 165 tonnes of koi carp per year. This decreases with increased harvesting to $5 per kg at 205 tonnes of koi carp per year. If the sales price of the dry pet food is $8/kg, the profit obtained processing 165 tonnes of fish per year is $52K, while at 205 tonnes per year, it is $83K. Dry pet food at the supermarket retails for $5 to $15 per kg.

text: Rendering koi carp and creating economic value by making pet food Koi carp is an invasive species fish in New Zealand that severely destroys the aquatic environment in the waterways in the Waikato region. The aim of the project was to look for a method that could make use of captured koi carp. Wet rendering and autoclave rendering was examined for producing fish meal and oil under different processing conditions such as time, temperature and water content.
The water content of raw minced fish was around 69-77%, the solids content was between 23%-31%. Ash content was 6.2-7.4% of the dry solids and fat content between 13.7%-30%. Fish with a high fat content were females containing roe. The meal produced from wet rendering contained 22-28% solids, with 5-9% ash and 14-16% fat on a dry basis, while the stickwater contained 3% solids and 12-39% ash on a dry basis. Autoclave rendering produced a meal containing 26-30% solids, 3-5% ash and 30-31% fat on a dry basis and a stickwater containing 3.2% solids and 27-32% ash on a dry basis. Fat reduction in meal increased with rendering time for wet rendering up to 30% at 40 minutes rendering time, while only a 20% reduction in fat was achieved for autoclave rendering. Wet rendering was selected for producing meals.
Dry pet food and wet pet food was made by mixing rendered fish meal with chicken mince. The dry food was produced by baked while the wet food was produced by steaming. Taste testing showed that cats preferred wet pet food over the dry pet food. The dry pet food had a strong odour and poor palatability. Most cats in the taste testing hesitated to try or eat much of the dry food. It was hard for them to chew the nibbles. Less koi carp meal should be used to improve palatability. The majority of the wet pet food was consumed and it had a better odour.
A customer survey showed acceptance of koi carp for pet food was high. 92% of the participants felt they would buy or try later. People who have pets were more open-minded about using pet food made from koi carp.
An economic analysis showed that 165 tonnes of koi carp could be harvested per year from four Waikato lakes by Huntly, maintaining a biomass density of 140 kg/hectare, down from the current average density of around 200 kg/hectare. To reduce the density down to 100 kg/hectare, koi carp would need to be harvested at 205 tonnes per year for the first 12 years, reducing harvesting to 170 tonnes per after this. Wet pet food production is much more profitable than dry pet food production. The price of each 100 g can of wet pet food to break even should be around $1.7 which is comparable to supermarket prices. This is approximately 10 times the price of dry pet food on a per kg basis. The profit made at $2 per can at 165 tonnes of fish per year is $408K while at 205 tonnes of koi carp the profit is $526K. Dry pet food needs to be sold at just under $6 per kg to breakeven at 165 tonnes of koi carp per year. This decreases with increased harvesting to $5 per kg at 205 tonnes of koi carp per year. If the sales price of the dry pet food is $8/kg, the profit obtained processing 165 tonnes of fish per year is $52K, while at 205 tonnes per year, it is $83K. Dry pet food at the supermarket retails for $5 to $15 per kg.

year: 2020

title: Thermomechanical processing of cost-affordable powder metallurgy Ti-5Fe alloys from the blended elemental approach: Microstructure, tensile deformation behavior, and failure

authors: Romero Villarreal, Carlos

subjects: Science & Technology

abstract: The development of cost-affordable Ti alloys is key for the application of Ti in other industries like the automobile sector. Therefore, a combination of powder metallurgy (PM) and low-cost compositions is an interesting approach. In this article, a cost-affordable PM Ti-5Fe alloy is processed following the blended elemental route and extruded at high temperature to remove porosity. Different extrusion temperatures and heat treatments (i.e., solution treatment and aging, STA) are performed to obtain ultrafine microstructures, and their effect on the mechanical behavior is studied. For extrusions in the β phase, microstructures consist of coarse lamellar colonies, resulting in alloys with improved properties compared to the as-sintered alloy but still lacking toughness due to the failure happening just after necking onset. Extruding in the α + β phase results in a bimodal microstructure of fine elongated primary α and coarse lamellar colonies, and the alloy becomes tougher. STA with aging below the eutectoid temperature of 590 °C leads to a hard but brittle alloy, whereas STA with aging above it results in alloys with strength comparable to the as-extruded conditions and enhanced ductility.

text: Thermomechanical processing of cost-affordable powder metallurgy Ti-5Fe alloys from the blended elemental approach: Microstructure, tensile deformation behavior, and failure The development of cost-affordable Ti alloys is key for the application of Ti in other industries like the automobile sector. Therefore, a combination of powder metallurgy (PM) and low-cost compositions is an interesting approach. In this article, a cost-affordable PM Ti-5Fe alloy is processed following the blended elemental route and extruded at high temperature to remove porosity. Different extrusion temperatures and heat treatments (i.e., solution treatment and aging, STA) are performed to obtain ultrafine microstructures, and their effect on the mechanical behavior is studied. For extrusions in the β phase, microstructures consist of coarse lamellar colonies, resulting in alloys with improved properties compared to the as-sintered alloy but still lacking toughness due to the failure happening just after necking onset. Extruding in the α + β phase results in a bimodal microstructure of fine elongated primary α and coarse lamellar colonies, and the alloy becomes tougher. STA with aging below the eutectoid temperature of 590 °C leads to a hard but brittle alloy, whereas STA with aging above it results in alloys with strength comparable to the as-extruded conditions and enhanced ductility.

year: 2020

title: Lake weed and the Rotorua Te Arawa Lakes then and now

authors: Burton, Tracy

abstract: This afternoon we will be looking beneath the surface of the Rotorua
Te Arawa lakes at the submerged aquatic plants that grow within them – the good the bad and the ugly. We will have a look at the special native aquatic plants that occur naturally in the lakes, familiarise ourselves with the weed species that have invaded them and look at how these weeds have (and are) changed the natural condition of the lakes. We will also look at how submerged plants are being used to report on the condition of our lakes and what these plant communities can tell us about the state of the lakes yesterday and today.

text: Lake weed and the Rotorua Te Arawa Lakes then and now This afternoon we will be looking beneath the surface of the Rotorua
Te Arawa lakes at the submerged aquatic plants that grow within them – the good the bad and the ugly. We will have a look at the special native aquatic plants that occur naturally in the lakes, familiarise ourselves with the weed species that have invaded them and look at how these weeds have (and are) changed the natural condition of the lakes. We will also look at how submerged plants are being used to report on the condition of our lakes and what these plant communities can tell us about the state of the lakes yesterday and today.

year: 2017