Depletion of ascorbic acid derivatives in fish feed by the production process

ABSTRACT:   The depletion of ascorbic acid derivatives in fish feed during the feed processing (extrusion cooking and drying) was studied at five extrusion cooking temperatures and at 85°C for 2 h dryer processing temperature. Three ascorbic acid derivatives were used: L-ascorbyl-2-mono-phosphate Mg (APM), L-ascorbic acid sodium (AAS) and L-ascorbic acid palmitic acid ester (AAP). Samples were collected after drying and ascorbic acid derivatives losses evaluated. APM was found to be quiet stable with an average retention of 88%, but AAS and AAP were unstable and the depletion was very high.     

Wheat gluten in extruded fish feed: effects on morphology and on physical and functional properties

This article focuses on understanding the role of vital wheat gluten on the structural parameters of extruded fish feed and its correlation to the physical and functional properties. Gluten–soy protein concentrate blends with five gluten concentrations (0–200 g kg⁻¹) were produced. An abrupt reduction in oil uptake was observed with the 200 g gluten kg⁻¹ blend. Inclusion of gluten from 100 to 200 g kg⁻¹ resulted in unacceptable product properties. Sinking of feed pellets with 0 and 50 g gluten kg⁻¹ was 100%, whereas only 36% of pellets with 200 g gluten kg⁻¹ sank. We suspect that this is due to a relationship between morphological structure and oil impregnation during coating of feeds. The addition of gluten at 200 g kg⁻¹ gave a smoother and non‐porous outer surface. Pellets without gluten had a larger number of cells that were smaller than 200 μm (P < 0.05) compared with pellets with 100 and 200 g gluten kg⁻¹. More spherical cell shapes (P < 0.01) and a compact structure were favoured in the presence of gluten. The closed porosity increased (P < 0.05), whereas interconnectivity between pores decreased (P < 0.01), with increasing gluten content from 0 to 200 g kg⁻¹. The effects of the addition of gluten are probably related to the film‐forming properties of gluten.     

A review of the effects of ingredient composition and processing conditions on the physical qualities of extruded high‐energy fish feed as measured by prevailing methods

Feed comprises the biggest cost in intensive fish farming and the quality of feed is therefore important. A vast body of research has been carried out in order to investigate nutritional quality of alternative ingredients. Effects of ingredients on physical quality are seldom included in these investigations. Physical quality of feed varies with ingredient composition and processing condition and may interfere with feed intake, nutrient digestibility and therefore growth performance of the fish. In this review, physical quality of extruded, high energy feed, and how ingredient composition and processing conditions affect the quality will be addressed. Various pellet properties will be discussed and methods used to evaluate physical quality will be reviewed.     

挤压蒸煮技术在水产饲料业的应用

我国饲料工业是一个新兴的产业,起步于20世纪70年代中后期,首先是畜禽饲料业的发展,直到80年代初水产饲料工业才开始启动。我国饲料工业生产的配合饲料产量呈直线上升,产值位居我国国民经济41个主要行业中的第20位,成为国民经济的基础产业之一[1~3]。20世纪80年代以来,我国的水产饲料工业发展很快,对我国水产养殖业的高产、稳产起了重要作用。但随着养殖规模的不断扩大以及养殖品种的多样化发展趋势,对水产饲料的要求也越来越高,传统加工方法生产的配合饲料已难以适应现代水产养殖业发展的需要,而应用挤压蒸煮技术生产的颗粒膨化饲料能较好…     

热塑挤压蒸煮对鱼肉蛋白质营养价值的影响初探

采用胃蛋白酶—胰酶复合处理法对原料鱼肉、蒸煮和罐藏处理的鱼肉产品,以及热塑挤压蒸煮的鱼肉制品进行蛋白质体外消化率的测定,分析比较各种鱼肉制品的蛋白质体外消化率的测试结果;结果表明,挤压蒸煮对鱼肉蛋白质的消化率有一定的影响。     

利用膨化浮性饲料养殖加州鲈生产效果分析

实验将加州鲈(Micropterus salmoides)鱼苗用膨化浮性饲料养成商品鱼,对膨化浮性饲料养殖加州鲈生产效果进行了分析。结果显示:在114 d鱼种养殖期内,加州鲈从5 g长至112 g,比预定的出塘规格(100 g)高出12%,饵料系数为1.14,表明鱼种阶段,加州鲈对膨化饲料有良好的反应。在159 d商品鱼养殖期内,加州鲈从155 g长至354 g,生长缓慢,平均饵料系数为1.43。     

Effects of Particle Size and Processing Variables on the Properties of an Extruded Catfish Feed

Abstract

A catfish feed was extruded to determine how particle size, moisture content and screw speed affected the pellet durability, water stability index, and buoyancy. Increasing moisture content from 250 to 300 g/kg required less die pressure, specific mechanical energy and product temperature to produce durable pellets that were stable in water. Increasing screw speed from 200 to 400 rpm also lowered die pressure, due to a lower filled length of the extruder screw channels, but increased specific mechanical energy and product temperature; the resulting pellets had a lower apparent bulk density, but a higher degree of starch gelatinization and water stability index. Reducing particle size from 1200 to 700 m decreased die pressure and apparent bulk density, but increased product temperature, degree of starch gelatinization, pellet durability index and water stability index.     

Growth performance and the soft body composition of juvenile abalone,Haliotis discus,Reeve 1846, fed the extruded pellets substituting fish meal and macroalgae with tunic meal of sea squirt,Halocynthia roretzi

Growth performance and the soft body composition of juvenile abalone fed the extruded pellets (EPs) substituting fish meal (FM) and macroalgae (MA) with tunic meal of sea squirt (SS) was investigated. A total of 1,260 abalone were distributed into 18 containers. Six experimental diets were prepared in triplicate. Five diets were pelletized by an extruder pelleter. The 140 g/kg FM and 250 g/kg mixture of MA were included into the control (Con) diet. Five hundred and 1,000 g/kg of each FM and MA were substituted with an equal amount of tunic meal of SS, referred to as the FM50, FM0, MA50 and MA0 diets, respectively. Finally, dry Undaria pinnatifida was prepared. Weight gain and specific growth rate of abalone fed all EPs were greater than those fed U. pinnatifida. Weight gain of abalone fed MA50 and FM50 diets was greater than Con and FM0 diets, but not different from MA0 diet. Higher crude protein and lipid contents were observed in soft body of abalone fed all EPs compared to U. pinnatifida. In conclusion, FM and MA up to 500 and 1,000 g/kg, respectively, could be replaced with tunic meal of SS in EPs without retardation in growth of abalone.     

Pea and wheat starch possess different processing characteristics and affect physical quality and viscosity of extruded feed for Atlantic salmon

The aim of the study was to investigate the effect of starch source, retention time in the preconditioner and screw speed (RPM) on physical quality of extruded fish feeds. The experiment was arranged in a three by two by two factorial design using three carbohydrate sources [wheat starch (WS), pea starch (PS) or a combination (WS_PS)], two retention times in the preconditioner [long (120 s) or short (62 s)] and two RPM in the extruder [high (300) or low (220)]. Physical quality was assessed by hardness, diameter, expansion ratio, Holmen durability (HDI), DORIS value (DV), oil absorption capacity, oil leakage and pasting viscosity. The results showed that retention time in the preconditioner only affected HDI and oil leakage. Long retention time improved HDI but caused a greater leakage. Changing screw speed from 220 to 300 RPM gave a greater expansion ratio, improved HDI and oil absorption. PS resulted in higher pasting viscosity, HDI and DV, but a generally lower hardness than WS. To conclude, PS and WS have different processing characteristics, and the conditions need to be adjusted according to the starch source used when producing extruded fish feed.     

Influences of feeding frequency of extruded pellet and moist pellet on growth and body composition of juvenile Japanese flounder <Emphasis Type="Italic">Paralichthys olivaceus</Emphasis> in suboptimal water temperatures

This study was carried out to investigate the influences of feeding frequency of extruded pellet and moist pellet on growth and body composition of juvenile flounder (initial mean weight 6.3 g) in sub optimal water temperatures. A 2 (diets: extruded pellet and moist pellet)×2 (feeding frequencies: two and three times daily)×2 (water temperatures: 12 and 17°C) factorial design with three replications was used. After 60 days of feeding, the feeding frequency did not significantly affect growth performance of fish. Weight gain, daily feed intake, feed efficiency and protein efficiency ratio were significantly (P<0.05) higher for fish reared at the higher water temperature. At the same water temperature, weight gain, feed efficiency, and protein efficiency ratio were significantly (P<0.05) higher for fish fed the extruded pellet than moist pellet. The results of this study indicate that feeding frequency of two times daily is sufficient for optimal growth of juvenile flounder when reared in suboptimal water temperatures, and an increase in water temperature from 12 to 17°C improved growth and feed efficiency.     

Long-term evaluation of extruded diets compared with raw fish moist diet for growing Korean rockfish, Sebastes schlegeli (Hilgendorf)

A long‐term experiment was conducted in sea cages to compare three experimental extruded pellet (EP) diets with a raw fish moist pellet (MP) diet for Korean rockfish, Sebastes schlegeli (Hilgendorf). White fishmeal (WFM), soybean meal (SM) and fishmeal analogue (BAIFA‐M?)‐based experimental EP diets were formulated to be isonitrogenous and isocaloric with 50% crude protein (CP) with available energy of 16.7 kJ g^?1 diet. An MP diet made of 80% frozen horse mackerel + 20% commercial binder meal was also included in the experiment. The proportions of the major protein ingredients in three experimental EP diets were as follows: WFM diet, 100% WFM; SM diet, 70% WFM + 30% SM; BAIFA‐M? diet, 70% WFM + 30% BAIFA‐M?. The experiment was divided into three periods according to fish size: period I, initial weight of 20.2 ± 3.6 g (mean ± SD); period II, initial weight of 57.6 ± 4.7 g (mean ± SD); period III, initial weight of 96.3 ± 6.9 g (mean ± SD). There were no significant differences in weight gain, feed efficiency ratio, thermal‐unit growth coefficient, specific growth rate, haemoglobin, or haematocrit among fish that were fed the four diets during all three periods. However, fish that were fed the MP diet had a lower survival rate than the fish that were fed the other three EP diets for all periods. These results strongly suggest that EP diets could be developed to replace MP diet for the grow‐out stage of production of Korean rockfish without adverse effects on growth performance.     

不同淀粉源对水产膨化饲料加工及品质特性影响研究进展

淀粉在水产膨化饲料加工过程中起着非常重要的作用,不仅能增强物料的粘性,在膨化饲料中起到膨胀和粘合的双重作用。由于不同来源淀粉的颗粒结构不同,其对水产膨化饲料加工和品质等产生的影响也存在差异。本研究综述了不同淀粉源的基本特性与水产膨化饲料加工及品质特性之间关系的研究进展,分析不同淀粉源淀粉的组成、结构、糊化特性、流变特性和热力学特性等方面的差异,比较不同淀粉源对水产膨化饲料品质特性的影响,并对不同淀粉源在研究过程中存在的问题、发展方向进行展望。     

热塑挤压蒸煮处理对鱼肉蛋白分子影响的研究

用热塑挤压蒸煮加工技术与传统食品加工技术比较了不同加工技术对鱼肉蛋白分子的影响.通过采用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳对原料鱼肉,3种传统加工方法即常规蒸煮、热力杀菌和鱼糜加工处理的鱼肉制品及热塑挤压蒸煮的鱼肉制品进行蛋白质分子量的测定,分析比较各种鱼肉制品的蛋白质分子量的测定结果,初步探索了热塑挤压蒸煮对鱼肉蛋白质分子量的影响.研究结果表明,热塑挤压蒸煮对鱼肉蛋白质的分子量有一定的影响.     

鱼肉蛋白质挤压过程中操作参数对挤出物水分含量及堆积密度的影响

研究了鱼肉蛋白质在双轴挤压蒸煮处理过程中,主要操作参数末段腔体温度,螺杆转速和供料水分含量对挤出物的水分含量和堆积密度两个物理性质的影响。研究的3个操作参数每一个变量设5个水平,测量相应挤出产物的水分含量和堆积密度,分别建立挤出物水分含量与操作参数,挤出物堆积密度与操作参数的回归拟合方程。结果表明,供料湿度明显影响挤出物的水分含量。供料水分含量、腔体温度和螺杆转速对挤出物的堆积密度都有影响;水分含量与操作参数,堆积密度与操作参数的回归拟合方程的相关系数R²分别是1.000和0.926,拟合的统计模型可信度高。     

鱼肉蛋白质热塑挤压组织化中过程参数的优化模型

挤压蒸煮处理可以改变鱼肉蛋白质的功能特性,这些改变与挤压机的操作参数是密不可分的。利用响应面分析方法讲究Clextral BC-45型双轴挤出蒸煮机的操作参数对鱼肉蛋白质进行热塑挤压组织化的影响。研究的3个操作参数分别是末段腔体温度,螺杆转速和喂料湿度,每一个变量设5个水平。测量作为组织化产物功能特性的持水性指数及质构特性,分别建立持水性与操作参数,质构特性与操作参数的回归拟合方程。研究结果表明喂料湿度、螺杆转速和腔体温度对挤出物质构的影响是不同的;持水性与操作参数,质构特性与操作参数的回归拟合力方程的相关系数R^2分别是1.000和0.933,拟合的统计模型可信度高。     

Intrinsic settling rate and spatial diffusion properties of extruded fish feed pellets

Spatial and temporal feed distribution in sea cages are important factors for the farmer, fish and environment due to the strong relation to growth, feed loss, pollution and welfare. This study presents a set of experimentally derived diffusion parameters and settling rates obtained in still water from four sizes and three densities of extruded fish feed pellets commonly used in aquaculture. It was found that pellet size is positively correlated with increased diffusion and that pellet density plays a less important role. Both the size and density of pellets had a significant impact on the settling rate. Results are compared to values obtained during feed production as well as other relevant studies. The findings suggest that parameters related to hydrodynamic behaviour of groups of feed pellets may vary across different pellet types. The results may be applied to refine and parameterize pellet motion in sea cage feeding models, improving estimates of fish behaviour, growth and feed loss.     

Disaggregation rates of extruded salmon feed pellets: influence of physical and biological variables

The culture of salmonids in the marine environment has led to concern regarding eutrophication of the water column and sediment from uneaten feed. This study used measurement of mass loss and change in carbon and nitrogen content of feed to quantify material lost from waste feed as a function of physical and biological variables. A laboratory flume was used to measure changes in cooked–extruded salmon feed pellets as a function of pellet size (6.5 and 12.0 mm in diameter), residence time in seawater (0, 24, 48, 72 and 120 h), and flow speed (0, 9.3 and 22.2 cm s^?1). The influence of sediment on pellet degradation was also determined. Loss of pellet mass increased with water flow velocity. Smaller pellets eroded faster than larger pellets, losing 32% (6.5 mm) and 21% (12.0 mm) of their mass after 120 h in seawater. The presence of sediment during preconditioning increased the percentage mass loss of the small pellets only. The presence of sediment also resulted in a greater percentage loss of carbon, but not nitrogen, relative to non‐sediment samples. These results allow quantitative assessment of the dynamics of feed pellets in the marine environment with respect to prediction of impact from salmon culture.     

Standardized method for the Holmen pellet tester (NHP100) as a tool for evaluating the physical quality of fish feed

The fish feed production industry requires reliable methods measuring the physical quality of feed before it is being released to the customer. The Holmen pellet tester (NHP 100) could be adapted for this purpose, but the special characteristics of fish feed require particular care during testing. The aim of the study was to determine the standardized conditions for using the Holmen tester as a tool measuring the durability of fish feed. Screening tests were performed on commercial fish feed samples to assess the effects of temperature, pressure and cleaning the instrument between runs. The operating pressure was found to be the most important factor that can influence the results. The temperature of the operating air can also alter the results; increased temperatures can cause oil to melt and leak from the pellets. Cleaning the instrument between analyses can also affect the results. This study shows that when these factors are maintained at a standardized level, the Holmen pellet tester is a valuable tool for assessing the physical quality of fish feed giving additional information on the quality of feed pellets compared to other durability tests like DORIS.     

Effect of feeding ratio on growth and body composition of juvenile olive flounder Paralichthys olivaceus fed extruded pellets during the summer season

The effect of feeding ratio on growth and body composition of juvenile olive flounder fed extruded pellets was determined during the summer season. Thirty juvenile olive flounder (initial body weight of 17 g) per tank were distributed into 21, 180-l flow-through tanks. Seven treatments that included triplicate groups of feeding ratio in 5% decrement were prepared for this study: 100% (satiation), 95%, 90%, 85%, 80%, 75% and 70% of satiation. Fish in the control group were hand-fed to apparent satiation twice a day. Then feed allowance in the rest of the six groups was determined based on average feed consumption in the control group. The feeding trial lasted for 7 weeks. Survival was over 97% and was not significantly (P > 0.05) affected by the feeding ratios. Weight gain and SGR of fish fed to 100% of satiation were not significantly different from those fed to 95% of satiation but significantly (P < 0.05) higher than those of fish fed to 90%, 85%, 80%, 75% and 70% of satiation. Weight gain, SGR and feed consumption of flounder linearly (P < 0.001) decreased with a decrease in feeding ratio. However, feed efficiency ratio, protein efficiency ratio and protein retention in fish body were not significantly (P > 0.05) affected by the feeding ratio. The crude protein levels of the whole body without liver or liver were significantly affected by the feeding ratio. Hepatosomatic index and condition factor of fish were not significantly (P > 0.05) affected by the feeding ratio. It can be concluded that optimum feeding ratio for growth of juvenile olive flounder could be lowered to 95% of satiation without growth suppression.