Molasses

Molasses waste is a by-product generated from the process of obtaining refined white sugar from sugar canes as well as from papermaking industries.

From: Advances in Organic Farming , 2021

SYRUPS

M.A. Clarke , in Encyclopedia of Food Sciences and Nutrition (Second Edition), 2003

Molasses

Molasses (or treacle in the UK consumer market) is a general term for concentrated juice from sugarcane or sugarbeet, or raw cane sugar in concentrated solution after varying amounts of sucrose have been removed. Sugarcane molasses is the major food molasses. Both sugarbeet and sugarcane molasses are used for animal feed and as fermentation sources for ethyl alcohol and other chemicals. These uses are amply described in the literature and are not discussed here. Recent developments in technology have made possible some sugarbeet molasses food products; these are at present available in limited quantity. ( See SUGAR | Refining of Sugarbeet and Sugarcane.)

Several common terms for molasses are defined as follows. Blackstrap molasses is the byproduct from a sugarcane factory or raw sugar refinery; it is the heavy, dark viscous liquid remaining after the final stage of sugar crystallization from which no further sugar can be crystallized economically by the usual methods. Types of blackstrap are further defined by the US Department of Agriculture (USDA) as superior, normal, or utility, but these are ready definitions for feed-grade material.

High-test molasses is the product obtained by concentrating clarified cane juice to approximately 85   ° Brix; it is partially inverted with either acid or invertase enzyme. High-test molasses is produced from cane juice instead of sugar, not as a byproduct of sugar production. High-test molasses, also known as fancy molasses, cane invert syrup, or cane juice molasses, is a premium product, higher in sugars content and of a more aromatic flavor than blackstrap. It has been subjected to less heat than blackstrap, and so contains relatively fewer sugar decomposition products, which can add bitter flavor.

Sulfured molasses is the byproduct of raw sugar manufacture in which sulfur dioxide has been added to the molasses to bleach color. Sulfured molasses may be lighter in color, but it is higher in ash of the insoluble sulfate type. The term 'unsulfured' is more common. The approximate composition of cane molasses (blackstrap) is given in Table 1. (See PRESERVATION OF FOOD; individual constituents.)

Table 1. Approximate composition of cane molasses

Main constituents Components Normal range
Water 17–25%
Sugars Sucrose 30–40%
Glucose (dextrose) 4–9%
Fructose (levulose) 5–12%
Other reducing substances (as invert) 1–4%
Total reducing substances (as invert) 10–25%
Other carbohydrates Gums, starch, pentosans, also traces of hexitols; myoinositol, d-mannitol, and uronic acids 2–5%
Ash As carbonates a 7–15%
Bases:
Potassium oxide (30–50%)
Calcium oxide (7–15%)
Magnesium oxide (2–14%)
Sodium oxide (0.3–9%)
Metal oxides (as ferric) (0.4–2.7%)
Acids:
Sulfur trioxide (7–27%)
Chloride (12–20%)
Phosphorus pentoxide (0.5–2.5%)
Silicates and insolubles (1–7%)
Nitrogenous compounds Crude protein (as N × 6.25) 2.5–4.5%
True protein 0.5–1.5%
Amino acids, principally aspartic and glutamic acids, including some pyrrolidine carboxylic acids 0.3–0.5%
Unidentified nitrogenous compounds 1.5–3.0%
Nonnitrogenous Aconitic acid (1–5%), citric, malic, oxalic, glycolic 1.5–6.0%
Mesaconic, succinic, fumaric, tartaric 0.5–1.5%
Wax, sterols, and phosphatides 0.1–1.0%
Vitamins Thiamin (B1) 2–10 p.p.m.
Riboflavin (B2) 1–6 p.p.m.
Pyridoxine (B6) 1–10 p.p.m.
Nicotinamide 1–25 p.p.m.
Pantothenic acid 2–25 p.p.m.
Folic acid 10–50 p.p.m.
Biotin 0.1–2 p.p.m.

Source: United Molasses Company, London, UK. By courtesy of the Technology Division of Crompton and Knowles Corporation, Mahwah, NJ, USA.

a
Percentage of ash given in parentheses.

Most commercially available molasses, for consumer purchase or food industry use, is made by blending various cane factory and refinery molasses and syrups for desirable – and constant – flavor and quality.

Physical properties of molasses vary with composition. Viscosity can vary over several orders of magnitude depending on inorganic and polysaccharide composition and temperature. Cane molasses has an acid pH, usually between 5 and 7. The salts content (2–8%) can contribute buffering capacity, to stabilize flavors and prevent hydrolysis, and can also provide flavor for feed use.

Color and flavor are the major properties besides nutrition that molasses contribute to food processing. Molasses always contributes some sweetness, to a degree which usually decreases as color darkens. The range of flavors is broad, ranging from caramel, cane flavor in light high-test molasses, to heavy, bitter notes, sometimes with licorice characteristics. Extensive research has shown that molasses flavor is a complex mixture. Because of this wide range of flavors, molasses can be used to mask or disguise other, less pleasant flavors, e.g., bitterness of bran in wholewheat (wholemeal) products; as an enhancer in sauces and licorice products. Molasses can also be used as a coloring agent, for golden to dark brown colors, especially in baked goods, and as a color enhancer, or masking agent, to disguise gray or gray-brown tones. Molasses displays humectancy, colligative, and water absorption (lowering of water activity) properties that would be expected of a sucrose syrup of similar solids composition; these properties lead to wide application in intermediate-moisture foods and in baked goods with extended shelf-life. However, nonsugars in molasses apparently have some effect on humectancy: molasses has been shown to be more effective in retaining a high moisture content than either sucrose or corn syrups. Molasses nonsugars also exhibit an antioxidant effect, significant when this fraction is used at some 3% of the fat level in the food product, and important for health foods. Inclusion in whole-grain products is one potential role for this fraction. (See ANTIOXIDANTS | Natural Antioxidants; COLORANTS (COLOURANTS) | Properties and Determination of Natural Pigments.)

Molasses is a food product that has often been claimed to be a secret of youthful behavior and appearance (e.g., to inhibit hair graying). Technological investigations, such as the isolation and characterization of the antioxidant fraction, may provide a scientific basis for what formerly appeared to be myths.

A dried molasses product, usually mixed with corn syrup solids to absorb water, is also available for use in dry mixes.

Syrups and molasses products sold to the food industry represent the result of blending various molasses and syrups to produce products of consistent color, flavor, and functional properties. Table 2 lists several typical blends, their composition, flavor characteristics, and potential applications. These blends are typical of material sold directly to the consumer as molasses in the USA, and as treacles, syrups, or blends in, other countries.

Table 2. Molasses and syrup blends

Characteristicdescription (%) Unsulfuredmolasses (%) Bakery molasses(%) Confectionery and all-purposemolasses (%) Condiment molasses(%) Robustmolasses
Composition
  Sucrose 35 32–36 33–37 30–36 33–37
  Invert 37 36–40 28–32 21–27 16–20
  Total sugars 72 70–74 63–67 54–60 51–55
  Ash 2.5 1.2–2.5 4.5–5.5 6.5–8.5 8.0–9.0
Color Golden brown Light brown Medium brown Dark brown Dark brown
Flavor Sweet, mild aroma, syrup flavor Sweet mild,distinctive Moderate sweet,strong aroma Strong, pungentflavor,goodbackground Strong flavor heat-resistant
Humectancy Some Good Good Some Some
Buffer effect Yes Yes Yes
Applications Table syrups,toppings, peanutbutter, fruit purées,confectionery, and alcohol products Fruit cakes, brownies, muffins, spiced baked goods Barbecue sauce,extended products,candies (hardand caramel),toasted foods,gingerbread Fermented products,condiments,and sauces Leavened andfermentedgoods,soy sauce,tobacco, licorice,baked beans,caramel, snacks

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Solvent Production

N. Qureshi , in Encyclopedia of Microbiology (Third Edition), 2009

Sugarcane Molasses

Cane molasses was successfully used in the commercial production of butanol in South Africa (National Chemical Products (NCP) Germiston, South Africa) until the early 1980s. Unfortunately, fermentation of butanol was terminated due to molasses shortage caused by severe drought. Molasses contains approximately 50% sucrose, which can be hydrolyzed to glucose and fructose by butanol-producing cultures. This substrate is easy to handle as it requires only dilution prior to fermentation. There are a number of molasses types that can be used including beet, blackstrap, and invert (high-test) molasses.

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Value of Feeds for Horses

In Horse Feeding and Nutrition (Second Edition), 1991

D. Sugarcane Molasses

Sugarcane molasses (also called cane molasses or blackstrap molasses) is an excellent feed for horses. It increases palatability and reduces dustiness in the diet. It also adds moisture, which is helpful in the pelleting of feeds. Molasses contains 4.3% protein, but no information is available as to how digestible the protein is for the horse. Some of it is in the form of nonprotein nitrogen (NPN) compounds, which have limited value for the horse. Molasses is usually added at a level of 5–15% in the concentrate feed. Therefore, it would be contributing only a small amount of protein to the total diet. In hot, humid areas, molasses should be limited to between 5 and 10% of the diet. Higher levels might cause wetness in the feed and result in mold growth.

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Caramels, fondants and jellies as centres and fillings

W.P. (Bill) Edwards , in Science and Technology of Enrobed and Filled Chocolate, Confectionery and Bakery Products, 2009

Molasses

Molasses are the residue left after the crystallisation of sucrose. It is relatively little used in confectionery apart from in the manufacture of liquorice, which is its largest use, and in making treacle toffee. In this product the treacle adds colour and flavour. The definition of treacle in some dictionaries is sufficiently wide to include golden syrup, however in this work treacle means a black syrup made by diluting molasses. Golden syrup is a golden coloured syrup produced by partially inverting a cane sugar syrup, which could be regarded as the equivalent of invert sugar lightly contaminated with molasses. Golden syrup is occasionally used in confectionery for flavour and colour

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Carbon-Rich Wastes as Feedstocks for Biodegradable Polymer (Polyhydroxyalkanoate) Production Using Bacteria

Jasmina Nikodinovic-Runic , ... Kevin E. O Connor , in Advances in Applied Microbiology, 2013

7.1 Molasses

Molasses, the honey-like viscous syrup, is the most valuable by-product from the sugar industry. It is residual syrup from which no more crystalline sucrose can be obtained by simple techniques. The composition varies depending on the source and type of refining (cane molasses, beet molasses, sulfured, and unsulfured); however, the sugar content is about 50% (predominantly sucrose with less amount of glucose and fructose), about 4% protein, trace elements calcium, magnesium, potassium, and iron) and vitamins (vitamin H or B7) ( Paturau, 1982). It is estimated that from about 100 tons of processed cane, 10 tons of sucrose, and 4 tons of molasses is extracted (Yadav & Solomon, 2006). Molasses is considered as a low-value product that is used as a soil fertilizer, a cattle feed supplement, in specialized yeast fermentations (production of citric acid, glutamate, and acetone), as a flavoring agent in some foods, or as a feedstock for ethanol production (Gopal & Kammen, 2009; Yadav & Solomon, 2006).

The production of molasses is highly correlated with the production of sugar, and by extension sugarcane and sugar beets. Global production of molasses amounts to around 50 million tons per year. Although commercially important, only about 15% of total molasses produced is traded internationally due to considerable price fluctuations (price is usually 35–50% of the price of glucose, Zhang, Obias, Gonyer, & Dennis, 1994) and due to the fact that it is a difficult product to store and transport. In 2007, 80% of the molasses traded was captured by the bioethanol industry (CBI, 2009; Solomon, 2011). Despite this the production of excess molasses as a residue from sugar processing is still occurring resulting in waste management costs. Thus, the use of molasses as a carbon feedstock for PHA production is a good alternative to the disposal of molasses. Indeed, a considerable amount of effort has been employed for conversion of molasses into PHA (Albuquerque, Torres, & Reis, 2010; Albuquerque et al., 2007; Koller, Atlic, et al., 2010; Koller, Hesse, et al., 2010; Koller et al., 2005).

The early investigation of molasses as a substrate for PHA production was undertaken using a mutant strain of Azotobacter vinelandii UWD when a production of 2.5   g/l PHB on a shaking flask scale after 24   h of cultivation was reported (Page, 1992; Table 4.2). The production of PHB from molasses by sucrose-utilizing recombinant organisms, namely E. coli, Klebsiella oxytoca, and Klebsiella aerogenes, was investigated by Zhang et al. (1994). The authors described the accumulation of about 3   g/l PHB on a shaking flask scale after 37   h of cultivation, corresponding to ~   50% of PHB in cdw. Solaiman et al. successfully utilized soy molasses for the production of medium-chain-length PHA using Pseudomonas corrugata. A cell density of 3.4   g/l and a total PHA content of 5–17% cdw were achieved when 5% (w/v) soy molasses was added to the E-medium. The mcl-PHA produced was poly(3-hydroxydodecanoate-co-3-hydroxyoctanoate-co-3-hydroxytetradecenoate), (P(3HDD-3HO-3HTDE)) (Solaiman et al., 2006). Albuquerque et al. observed the production of 30% cdw P(3HB-co-3HV) with a highest cell concentration of 3.5   g/l, from a mixed bacterial culture using sugarcane molasses. A sequencing batch reactor operated under aerobic dynamic feeding (feast and famine) was used (Albuquerque et al., 2007). In a 10-l bioreactor, Braunegg et al. reported the production of PHB from green syrup (another intermediate from sucrose production) and sugar beet molasses by different strains of Alcaligenes latus (DSM 1123 and 1124). Between 3 and 3.6   g/l PHB was accumulated from both substrates within a 15-h fermentation (Braunegg et al., 1999).

Table 4.2. PHA production from sugar industry and agricultural crop residues

Waste stream Producing microorganism Type of polymer Productivity (g/l) PHB (% cdw) Reference
Molasses
Beet Azotobacter vinelandii UWD mutant strain PHB 4.3 24 Page (1992)
Beet Alcaligenes latus DSM1124 PHB 3 30 Braunegg, Genser, Bona, and Haage (1999)
Beet Bacillus megaterium PHB 1.5 50 Omar, Rayes, Eqaab, Viss, and Steinbüchel (2001)
Cane Azotobacter beijerinckii DSM1041 PHB 3.7 41 Purushothaman, Anderson, Narayana, and Jayaraman (2001)
Cane Bacillus sp. COLI/A6 PHB 3.3 55 Santimano, Prabhu, and Garg (2009)
Cane Mixed culture PHBV 1 30 Albuquerque, Eiroa, Torres, Nunes, and Reis (2007)
Soy Pseudomonas corrugata mcl-PHA 0.6 17 Solaiman, Ashby, Hotchkiss, and Foglia (2006)
Other by-products of sugar industry
Sugarcane bagasse Burkholderia sacchari IPT 101 PHB 62 Silva et al. (2004)
Raw vinasse Haloarcula marismortui MTCC1596 PHB 2.8 23 Pramanik et al. (2012)
Pretreated vinasse Haloarcula marismortui MTCC1596 PHB 5 30 Pramanik et al. (2012)
Pretreated vinasse Haloferax mediterranei DSM1411 PHBV 19.7 70 Bhattacharyya et al. (2012)
Starch and bran residues
Raw starch Saccharophagus degradans PHB 1.3 17 Gonzalez-Garcıa, Rosales, Gonzalez-Reynoso, Sanjuan-Duenas, and Cordova (2011)
Raw starch Bacillus cereus CFR06 PHB 0.48 48 Halami (2008)
Raw starch Aeromonas sp. KC007-R1 (Cupriavidus necator pha genes) PHB 0.6 33 Chien and Ho (2008)
Potato starch residues Ralstonia eutropha NCIMB11599 PHB 94 55 Haas, Jin, and Zepf (2008)
Starch/yeast extract Haloferax mediterranei PHBV 0.84 43 Chen, Don, and Yen (2006)
Hydrolyzed corn E. coli JM101/DH10B (Cupriavidus necator pha genes) PHB 1.34 55 Fonseca, de Arruda-Caulkins, and Vasconcellos-Antonio (2008)
Wheat bran hydrolysate Halomonas boliviensis LC1 PHB 1 34 Van-Thuoc, Quillaguaman, Mamo, and Mattiasson (2008)
Mix of extruded rice bran and extruded corn starch Haloferax mediterranei PHBV 77.8 56 Huang, Duan, Huang, and Chen (2006)

Cane molasses was found to be an excellent substrate for the growth of Bacillus sp. COLI/A6 and for subsequent PHB production by Santimano and coworkers (Table 4.2). A total biomass and PHB content of 6   g/l and 54.68% cdw, respectively, were achieved using cane molasses as the main carbon source in the production medium in batch fermentation (Santimano et al., 2009). Omar and coworkers have also observed successful production of PHB by Bacillus megaterium on a range of substrates such as date syrup, beet molasses, and the corresponding pure carbohydrates in defined media (Omar et al., 2001). A cell concentration of 3   g/l and PHB content of 50% cdw were achieved when 5% (w/v) beet molasses was supplied to the production medium. In each case, positive impacts of the inexpensive, complex substrates was observed due to additional compounds included in these feedstocks (Omar et al., 2001). Beneficial effect of minor compounds such as metals contained in untreated molasses, but not in refined sugar, on microbial growth and PHB production was also reported for PHB accumulation from molasses by Azotobacter beijerinckii (Purushothaman et al., 2001).

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Industrial Biotechnology and Commodity Products

J.O.B. Carioca , M.R.L.V. Leal , in Comprehensive Biotechnology (Second Edition), 2011

3.04.2.4 Molasses

Molasses is probably the cheapest feedstock for ethanol production; it is a byproduct of the sugar factories so it is available in any sugar-producing region and there is an international trade of this commodity. There are many applications for molasses ranging from beverages, glycerol, acetic acid, baker's yeast, and lysine through fermentations, and as animal feed component or even fertilizer. The composition of molasses varies considerably depending on the non-sucrose in the raw juice and processing technology, but it can be considered approximately, for sugarcane molasses, as 75–85% of total solids, 30–36% sucrose, 10–17% (fructose  +   glucose), 10–16% ash, and some smaller quantities of polysaccharides, oligosaccharides, organic acids, proteins, and nitrogen compounds [9]. With some 50% content of fermentable sugars, it is indeed a good feedstock for the fermentation process. The sugar beet molasses has a similar composition, but lower concentration in reducing sugars and higher in sucrose.

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Challenges and prospective trends of various industrial and solid wastes incorporated with sustainable green concrete

Salmabanu Luhar , ... Kamarudin Hussin , in Advances in Organic Farming, 2021

14.2.2.8 Molasses waste

Molasses waste is a by-product generated from the process of obtaining refined white sugar from sugar canes as well as from papermaking industries. Chemically, it possesses lingo-sulfonate which is used as a scattering reagent which prevents agglomeration; super plasticizer to improve physical attributes like workability, durability and strength of concrete structures. Its usage as a plasticizer can be considered as most critical chemical additions. They are helpful in structural designing as well as diminish the amount of water embodied in the mixture of concrete. Bolobova and Kondrashchenko ( Kotresh and Belachew, 2014) have used it as super plasticizer in the mix of concrete as well as the analysis of the fundamental rules of the influences of components of both inorganic as well as organic origin from molasses of wastes obtained from the process of fermentation of yeast, on the attributes of the concrete linking system. An adding up of two dissimilar, i.e., 0.5% with 1% of molasses diminish water to cement ratio and also affects the durability of concrete adversely and declines the price value of concrete manufacturing with green concept as found in the study of Akar and Canbaz (2016) (Fig. 14.11).

Fig. 14.11

Fig. 14.11. Chemical compositions of molasses (Jumadurdiyev et al., 2005).

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Feedstuffs for horses

Jan Erik Lindberg , in Equine Applied and Clinical Nutrition, 2013

Sugar-rich feedstuffs

Molasses (beet and cane) and syrup (hydrolyzed starch) mainly contain sugars and are low in fat. The crude protein content varies, and is markedly lower in cane molasses than in beet molasses ( Table 17-6). The ash content is high in molasses products (12–14% DM), and potassium in particular is high compared with other common feedstuffs (apart from roughage). In general, the energy content in this group of feedstuffs is high.

Simple sugars (glucose and fructose) are well utilized by the horse and are absorbed in the small intestine (Meyer 1992). This is reflected in a rapid increase in plasma glucose values, with a similar response for both glucose and fructose (Bullimore et al 2000). As shown by Jansson et al (2002) adult horses have no problems to digest and utilize hydrolyzed starch (glucose : maltose:maltotriose proportion of 83 : 15 : 2) at levels of 2.5 g/kg BW per day. In contrast, there are limitations in the digestive capacity of certain disaccharides depending on age and the change in secretion of digestive enzymes (Meyer 1992). Thus, in the foal lactose is well utilized due to a high activity of lactase, while sucrose is less efficiently utilized due to a limited activity of sucrase. The situation is the reverse in the adult horse. According to Meyer (1992), the upper limit to dietary inclusion of lactose in the adult horse is 1 g/kg BW per day if digestive disturbances are to be avoided.

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Alcoholic Beverages: Current Situation and Generalities of Anthropological Interest

Arianna Núñez-Caraballo José D. García-García Anna Ilyina Adriana C. Flores-Gallegos L. Georgina Michelena-Álvarez Gerardo Rodríguez-Cutiño José L. Martínez-Hernández Cristóbal Noe Aguilar , in Processing and Sustainability of Beverages, 2019

2.2.1 Raw Materials of the Fermentation Process

Molasses is the final effluent from the extraction of sucrose from cane or beet juices. The proportion of molasses and its composition provide important information about the local conditions of production of the agricultural source (climatic conditions, nature of the soils, variety) ( Conde-Mejía et al., 2012) and at the same time the treatment received within the sugar factory (clarification, crystallization, among others). The molasses yield approximately 2.5%–3% of the milled cane and it is close to 25% of the sucrose produced, they are a very variable product and can change its composition and quantity from batch to batch within the factory.

Conventional ethanol production uses cane molasses at high concentrations of sugar and is carried out under anaerobic conditions. Some of the nonsugar components in the final honeys of cane have sufficient weight in the production of ethanol, which justifies their detailed attention (Hernández, 2014).

The ethanol yields are, if the operating conditions are favorable, 64   L of ethanol per 100   kg of sugars.

Cane juice is a direct source of sugars for alcoholic fermentation. The juice, which is defined as a diluted solution of sucrose, glucose, and fructose, is made up of water (about 82%) and soluble solids or Brix (about 18%). The secondary juices are the most suitable for alcoholic fermentation. Its purity is very high compared to molasses and other intermediate syrups, which results in higher fermentation efficiencies.

On the other hand, the yeast consumes the sugars in this order: glucose, sucrose, and fructose, in which the glucose induces the formation of its molecular transporters and represses the others, which are specific for each sugar. Table 2.1 compares the different factors that can affect alcoholic fermentation

Table 2.1. Characteristics of Sugary Substrates to Produce Ethanol by Fermentation

Factors Glucose/Sugars (%) Bacteria, ufc-mL Ashes (%) Ca:Mg Sludge (%) Colloids (%) Inferm (%) pH Acidity (%)
Molasses 34 103–104 9.4 2.8 6 9.3 4.4 5.5–5.7 0.69
Juice 5 ~   102–103 max 0.1 1.1 <   0.1 0.01 ND 4.6–5.1 0.8

Among the characteristics shown in Table 2.1, only the acidity and its association pH represent a greater risk for ethanolic production in juices than in honey. This is due to the fact that their dilution is very susceptible to microbial attack. However, because of the process of clarification to which they are submitted to the distillery, there is a drastic reduction in the bacterial content of an order of 102 and no yeasts or molds are detected, while in honey this does happen.

The osmotic pressure is significantly lower in juice than in honey as well, since it is proportional to the molar concentration of soluble substances (sugars and salts). This explains the values of higher yields and efficiencies based on sugars, which are obtained with the juices compared to the final honeys.

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Research and Results

Tzachi M. Samocha , in Sustainable Biofloc Systems for Marine Shrimp, 2019

14.1.1.6 2010

Growth is a major factor affecting the economic viability of intensive shrimp systems. It thus is important to use genetic lines with high growth potential. A 52-d no-water-exchange nursery trial was conducted to (1) monitor shrimp performance and changes in water quality throughout a nursery trial with no water exchange; (2) determine the impact of inoculating diatoms (40,000   cells/ml), adding nitrifying bacteria (3   m3 of nitrifying-rich water/raceway), and supplementing molasses on ammonia and nitrite levels; (3) determine if the small foam fractionators are adequate for biofloc control; and (4) evaluate performance of an online DO monitoring system (YSI 5200A, Yellow Spring, OH, US) with polarographic sensors and external wiper.

Four raceways were stocked with 11-day-old PL at 3500/m3. Postlarvae were from two genetic lines: the Fast-Growth line and the slower-growth Taura-Resistant line.

Molasses supplementation was more aggressive than in earlier trials: 0.5   L/d on days 1–4, 8–11, 14–17, 21–22, 24–25, 27, and 1   L/d/raceway on days 28–30. It varied on Day 18 between 2.85 and 3.5   L, depending on ammonia concentration in each raceway (e.g., adding 6   g of carbon for each 1   g of ammonia). From Day 35 until harvest, no molasses was added because ammonia was consistently below 0.5   mg/L. Molasses supplementation prevented ammonia accumulation but not nitrite. Nitrite-N increased up to 34.9   mg/L in one RW (Fig. 14.6) before dropping to low levels during Weeks 5 and 6.

Fig. 14.6

Fig. 14.6. Daily NO2-N in a 52-d nursery trial (2010) with Pacific White Shrimp at 3500   PL11/m3 in four 40   m3 raceways and no water exchange.

Take-home messages from the 2010 nursery trial—40   m3 raceway system:

✓

Algal inoculation, along with nitrifying-rich water and the organic carbon supplementation, helped maintain low ammonia (<   5   mg/L) throughout the trial,

✓

These additions did not prevent nitrite from reaching high concentrations, but they shortened the time for NOB to be established by more than 10   days (Fig. 14.6),

✓

Shrimp tolerated up to 17-d of exposure to NO2-N between 11.9 and 34.9   mg/L with no adverse effect on survival (>   97%),

✓

Nitrate-N increased throughout the trial, reaching almost 160   mg/L,

✓

Foam fractionators maintained TSS below 500   mg/L,

✓

Once again, the online DO monitoring system helped regulate feed and molasses applications and prevented DO drops below required levels,

✓

Molts prevented smooth operation of the DO probe's wipers, suggesting the need for a more reliable method of cleaning the membrane,

✓

Survival in both treatments was high, but Taura-Resistant shrimp had higher final weights and better FCRs than Fast-Growth shrimp (Table 14.6), and

Table 14.6. Performance of Fast-Growth and Taura-Resistant Pacific White Shrimp PL in a 52-d Nursery (2010) in Four 40   m3 Raceways at 3500   PL11/m3 and No Water Exchange in a Two-Replicate Trial

Treatment Wt. (g) Yield (kg/m3) Survival (%) FCR Water Use (L/kg Shrimp)
Taura-Resistant 0.97a 3.7a 97a 1.01 a 350a
Taura-Resistant 0.82a 3.1a 100a 1.05 a 394a
Fast-Growth 0.71b 2.9a 100a 1.12 a 396a
Fast-Growth 0.76b 3.1a 100a 1.21 a 375a

Values in columns with the same superscripts indicate no significant differences (P  &gt;   .05).

✓

Further information related to the nursery trial conducted in 2010 can be found in: Samocha et al., 2011a.

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