Chemical and nutritive characteristics of canola meal from Canadian processing facilities

https://doi.org/10.1016/j.anifeedsci.2016.09.012Get rights and content

Highlights

  • Differences in nutritive composition of canola meal between crushing plants exist.

  • Correlation between heat-sensitive components of canola meal is documented.

  • Meal overheating and protein damage may occur in some crushing plants.

  • Prediction of lysine and total dietary fiber from simple NDF analysis is proposed.

Abstract

Samples of canola meal (CM) were collected from eleven canola processing facilities in Canada over 4 successive years (2011–2014) to determine the chemical composition, indicators of protein damage and variability between processing facilities over time. In each year, each facility provided 3 samples and all samples were subjected to a complete chemical characterization which included proximate analyses, carbohydrates, dietary fiber with its components, total phosphorus and phytate phosphorus, and amino acids (AA) measurements. Overall, the contents of various components of CM over the 4 years in g/kg dry matter (DM) basis were as follows: crude protein (CP; Nx6.25) 417; fat 35.0; sucrose 61.0; oligosaccharides 29.0; total phosphorus 11.2; non-phytate phosphorus 3.80; neutral detergent fiber (NDF) 294; non-starch polysaccharides (NSP) 219; total dietary fiber 379; neutral detergent insoluble crude protein (NDICP) 54.0; lignin and polyphenols 107 and in μmol/g DM, glucosinolates 4.60. The mean AA contents were, in g/kg DM basis, lysine 21.1; arginine 22.7; histidine 11.7; isoleucine 12.5; leucine 25.9; methionine 6.9; cystine 8.4; phenylalanine 14.5; tyrosine 9.60; threonine 15.5, valine 17.4, alanine 17.1, asparagine 27.0, glutamine 67.2, glycine 18.0, proline 27.0, and serine 17.8. Over the 4 years, the highest variation was observed in the contents of simple sugars (CV = 41.7%), NDICP (CV = 16.8%) and glucosinolates (CV = 35.3%), the components known to be sensitive to heat treatment. Variations (P < 0.05) between processing facilities and years were also observed for CP, ether extract, ash, total phosphorus, simple sugars, oligosaccharides, NDF, NSP, NDICP, lignin and polyphenols, total dietary fiber and glucosinolates. Among all AA, only lysine showed differences (P < 0.05) between processing facilities. Lysine content averaged 18.5, 22.1, 22.9 and 20.7 g/kg in years 2011, 2012, 2013 and 2014, respectively, and was lowest in meals showing the highest NDICP and total dietary fiber values. Linear regression equations for predicting lysine, NDICP, and total dietary fiber from simple chemical compositions such as NDF and CP were developed. In conclusion, variations in the contents of CP, dietary fiber, NDICP, glucosinolates, and lysine among other components were observed for canola meals from crushing plants in Canada. These variations were mainly associated with differences in processing conditions (particularly heat treatment) in the various processing facilities. Indicators of CM quality such as NDICP, total dietary fiber, and lysine can be accurately predicted from NDF or NDF and CP contents.

Introduction

Canola is one of the most important oilseed crops in Canada and its processing for oil is an important part of the overall canola industry in Canada (Unger, 2011, Canola Council of Canada, 2015). Canola meal (CM), which is a co-product of the canola oil extraction process accounts for approximately 60% of the whole canola seed and is in most cases produced by pre-press solvent extraction with hexane. The pre-press solvent extraction process of canola requires a number of steps, each involving a wide range of temperature, moisture and time. All these conditions contribute to variations in the chemical composition and nutritional value of CM. For example, in the cooker, the temperature ranges from 85 to 95 °C, the moisture ranges from 4.5 to 6.0% and cooking lasts for 30–40 min. In the desolventizer/toaster (DT), the temperature ranges from 95 to 115 °C, and the process may last for 35–50 min (Unger, 2011, Canola Council of Canada, 2015). Studies have shown that excessive heating during pre-press solvent extraction may result in reduced concentration of amino acids (AA) particularly lysine. This is because Maillard reactions may occur between amino acids and reducing sugars as a result of the combination of heat and moisture applied to the meal in the DT (Nursten, 2005). Earlier research from our laboratory (Slominski, 1997) showed a profound effect of moist heat treatment on CM quality. Application of temperatures higher than 110 °C resulted in a significant increase in neutral detergent insoluble crude protein (NDICP) and dietary fiber contents and a significant decline in protein digestibility. Another study by Almeida et al. (2014) showed that autoclaving of CM at 103 °C for 20, 30 and 45 min increased NDF and acid detergent insoluble N and reduced the standardized ileal amino acids digestibility when fed to growing pigs. No study has been conducted to determine the effect of processing practises or conditions in the various processing facilities on the chemical compositions and information of Maillard reaction products in CM from Canadian processing facilities. Canola meal end-users desire increased meal consistency and more information on the nutritive value and heat damage of amino acids in CM (Spragg and Mailer, 2007). Therefore, the objectives of this study were: 1) To determine the effect of processing conditions on the chemical compositions and indicators of protein damage (Maillard reaction products including dietary fiber, NDICP, and lignin with associated polyphenols) in CM from Canadian processing facilities, 2) To determine the variations in the chemical composition of CM produced in Canada over time, and 3) To develop prediction equations for determining the components that can be used as indicators of heat damage including lysine, dietary fiber, NDICP, and lignin with associated polyphenols.

Section snippets

Canola meal sample collection and preparation

In years 2011, 2012, 2013, and 2014 CM samples were collected from 11 canola processing facilities in Canada which included: Bunge Oilseed Processing at Altona, MB; Harrowby, MB; Nipawin, SK; Fort Saskatchewan, SK and Hamilton, ON; Archer Daniels Midland (ADM) Agri-Industries Ltd. at Windsor, ON; Lloydminster, SK and Yorkton, SK; James Richardson International (JRI) Canola Oil Processing Plant at Yorkton, SK and Lethbridge, AB; Cargil Canola Processing, Clavet, SK. In each year, 3 samples were

Effect of processing facility and year on the chemical and nutritive composition of CM

As presented in Table 1, there were variations (P < 0.05) between processing facilities in the contents of CP (402–429 g/kg DM), ether extracts (26.0–43.0 g/kg DM), ash (71.0–79.0 g/kg DM), and total P (10.6–11.6 g/kg DM). However, there were no facility differences in phytate and non-phytate P contents. Canola meal from Facilities 1, 4 and 10 had similar and highest CP contents while those from Facilities 7 and 11 were significantly lower (P < 0.05) in CP than Facilities 1, 4 and 10. The overall mean

Discussion

The pre-press solvent extraction of canola meal consists of 10 basic stages which are: 1) Cleaning and drying of the seed to approximately 6% moisture, 2) Preconditioning (heating) to prevent shattering of the seeds during flaking, 3) Flaking by passing through a roller mill, 4) Cooking to deactivate myrosinase enzyme and to reduce oil viscosity and thereby coalesce the oil, 5) Expelling to reduce the oil content to approximately 15–20%, 6) Solvent extraction with hexane to remove additional

Conclusions

There were variations between processing facilities and years in the contents of CP, NDF, ether extract, total phosphorus, simple sugars, oligosaccharides, total dietary fiber, glucosinolates, NDICP, lignin and polyphenols and lysine of CM produced in Canada. The high total dietary fiber with the corresponding high NDICP and low glucosinolates with the corresponding low lysine observed in the CM from some processing facilities could have been caused by meal overheating and the consequent

Conflict of interest

The authors declare that they have no competing interests.

Acknowledgements

The authors wish to acknowledge the Canola Council of Canada and Agriculture and Agri-Food Canada for funding this project.

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