International Science Index


Effect of Modified Atmosphere Packaging and Storage Temperatures on Quality of Shelled Raw Walnuts


This study was aimed at analyzing the effects of packaging (MAP) and preservation conditions on the packaged fresh walnut kernel quality. The central composite plan was used for evaluating the effect of oxygen (0–10%), carbon dioxide (0-10%), and temperature (4-26 °C) on qualitative characteristics of walnut kernels. Also, the response level technique was used to find the optimal conditions for interactive effects of factors, as well as estimating the best conditions of process using least amount of testing. Measured qualitative parameters were: peroxide index, color, decreased weight, mould and yeast counting test, and sensory evaluation. The results showed that the defined model for peroxide index, color, weight loss, and sensory evaluation is significant (p < 0.001), so that increase of temperature causes the peroxide value, color variation, and weight loss to increase and it reduces the overall acceptability of walnut kernels. An increase in oxygen percentage caused the color variation level and peroxide value to increase and resulted in lower overall acceptability of the walnuts. An increase in CO2 percentage caused the peroxide value to decrease, but did not significantly affect other indices (p ≥ 0.05). Mould and yeast were not found in any samples. Optimal packaging conditions to achieve maximum quality of walnuts include: 1.46% oxygen, 10% carbon dioxide, and temperature of 4 °C.

[1] Crews C., Hough P., Godward J., Brereton P., Lees M., Guiet S. Study of the main constituents of some authentic walnut oils. Agriculture & food Chemistry 2005; 53, pp. 4853–4860.
[2] Zwarts L., Savage G. P., Mcneil D. L. Fatty acid content of New Zealandgrown walnuts (Juglans regia L). Food Science & Nutrition 1999; 50, pp. 189–194.
[3] Mexis S. F., Kontominas M. G. Effect of oxygen absorber, nitrogen flushing, packaging material oxygen transmission rate and storage conditions on quality retention of raw whole unpeeled almond kernels (Prunus dulcis). LWT – Food Science & Technology 2009; 43, pp. 1–11.
[4] Tajeddin B. A study of polymeric coverings in walnut kernel packaging. Research and Construction in Agriculture and Gardening magazine 2004; 62, pp. 2-8.
[6] Singh S. Modified Atmosphere Packaging of Fresh Produce: Current Status and Future Needs. LWT- Food Science & Technology 2010; 43(3), pp. 381-392.
[7] Caner, C. and Aday, M. S. Maintaining quality of fresh strawberries through various modified atmosphere packaging. Packaging Technology & Science 2009; 22: 115–122.
[8] Edalatian M, Sedaghat N, Sharif A. Effect of Temperature, Packaging Type and Preservation Time on Texture Stiffness of Ohadi Specie of Walnut and Comparison with Sensory Factors. National Conference of Pistachio Process and Packaging, Ferdosi University of Mashhad 2007; pp. 863-875.
[9] Vanhanen L. P., Savage G. P. The use of Peroxide Value as a Measure of Quality for Walnut Flour Stored at Five Different Temperatures Using Three Different Types of Packaging. Food Chemistry 2006; 99, pp. 64-69.
[10] Institute of standard and industrial research of Iran, Biscuit- Specifications and Test Methods. Standard 37; 1992.
[11] Parvane V. Quality Control and Foodstuff Chemical Experiments. Tehran University Press. 1992.
[12] Payan R. Quality Control Basis of Foodstuff. Abigh Press. 2003.
[13] Institute of standard and industrial research of Iran, Detection and Enameration of Moulds and Yeasts Colony Count Technique at 25°C. Standard 997, 10th Edition, 1992.
[14] Atkinson A C, Donev A N. Optimum experimental design. Oxford University Press.5, 1992; 132-189.
[15] Myers R. H., montgomery D. C. Response Surface Methodology: Process and Product Optimization Using Designed Experiments 2nd Ed. Wiley: New York, 2002; pp. 3-51.
[16] Fatemi H. Foodstuff Chemistry. Enteshar Co, Ltd, 2001.
[17] Raii M., Sedaghat N., Poorazarangh, Hashem N. Evaluating the Effects of Packaging Material and Designed Atmospheric Conditions on Physiochemical Characteristics of Pistachio. National Conference of Pistachio Packaging, Ferdosi University of Mashhad 2007, pp. 304 – 312.