Effect of moisture content, postharvest treatment, and storage

time on some properties and quality attributes of red lentil

Yang Zhang a

L.G. Tabilb, X. Lib, A. Opokub, Decheng Wanga, G. Argañosab

a China Agricultural Universityb University of Saskatchewan

2008 CSBE/SCGAB Annual Conference

OutlineIntroductionObjectiveMethodsResultsConclusions

2008 CSBE/SCGAB Annual Conference

2008 CSBE/SCGAB Annual Conference

IntroductionLentil (Lens culinaris L.), is one of the

most nutritious pulse grains due to its high content of plant protein.

Majority of red lentil is consumed after primary processing--dehulling.

Red LentilGreen Lentil Green Lentil

Introduction Dehulled lentil is consumed in whole

cotyledon (footballs) or in split cotyledon.

Dehulling

Dehulled football

Dehulled split

Cooking is the most traditional practice used to convert red lentil into consumable foods.

2008 CSBE/SCGAB Annual Conference

Introduction Some conceptions Water absorption—defined as the maximum

amount of water that 100 intact red lentils absorb at room temperature.

Dehulling efficiency—defined by the percent of dehulled whole seeds (%) and dehulled split seeds (%) obtained relative to the initial sample mass.

Cooking time—defined as the time required for 80% of the red lentil to be cooked.

2008 CSBE/SCGAB Annual Conference

Introduction What’s the problem? Basic physical properties Quality attributes

1. Dehulling quality—dehulling efficiency

2. Cooking quality—cooking timeChemical components

2008 CSBE/SCGAB Annual Conference

Objective Physical properties

100-seed weight

Water absorption

Dehulling quality

Cooking quality

Protein content

Moisture content

Postharvest treatment

Storage time

2008 CSBE/SCGAB Annual Conference

Methods Sample preparation Postharvest treatment

Storage time 0 month , 1 month , 2 months and 4 months

Red Lentil “Robin” Mc=10.07%

Mc=11.31%

Tempering

Initial McMc=9.62% Storage Temp. 5 ℃

Storage Temp. 25 ℃

2008 CSBE/SCGAB Annual Conference

Methods Measurement and apparatus Dehulling efficiency Cooking Time

Satake grain testing mill Automated Mattson cooker

2008 CSBE/SCGAB Annual Conference

a-PC; b-I/O card; c-interface box; d-circuit board assembly; e-actuator; f-plunger; g-Mattson cooker.

The abrasive wheel--1100 rpm; Time--38 s.

From: Canadian Grain Commission

Results – 100-seed weight

Sample (Moisture content, % w.b. and postharvest treatment)

100-seed weight (g)

Storage Time (month)

0 1 2 4

9.62% 5℃ 2.7591±0.0107 2.7463±0.0016 2.7342±0.0084 2.7176±0.0051

10.07% 5℃ 2.7829±0.0410 2.7768±0.0152 2.7748±0.0166 2.7687±0.0045

10.07% 25℃ 2.8183±0.0066 2.7987±0.0379 2.7920±0.0134 ------

11.31% 5℃ 2.8434±0.0380 2.8228±0.0128 2.8185±0.0197 2.8118±0.0141

11.31% 25℃ 2.8748±0.0090 2.8420±0.0086 2.8245±0.0167 ------

2008 CSBE/SCGAB Annual Conference

Results – Water Absorption

2008 CSBE/SCGAB Annual Conference

Dehulling efficiency

Note: Values (mean of three replicates) in the same column followed by the same letter are not significantly different by Duncan’s multiple range test (P < 0.05).

Results – Dehulling quality

Sample (Moisture content, % w.b. and postharvest treatment)

Dehulling Efficiency (%)Storage Time (month)

0 1 2 4

9.62% 5℃ 86.77 86.66 a 86.53 a 86.51 a10.07% 5℃ 86.72 86.65 a 86.54 a 86.46 a10.07% 25℃ 86.49 86.23 b 86.33 a ------11.31% 5℃ 86.71 86.12 b 85.77 b 85.75 b11.31% 25℃ 86.27 85.60 c 85.10 c ------

2008 CSBE/SCGAB Annual Conference

Cooking time

Results – Cooking quality

Sample (Moisture content, % w.b. and postharvest treatment)

Cooking time (min)Storage Time (month)

0 1 2 4

9.62% 5℃ 1.595 1.947 2.403 3.05710.07% 5℃ 1.651 2.213 2.700 3.30910.07% 25℃ 1.991 2.338 2.946 ------11.31% 5℃ 1.940 2.797 3.266 3.77311.31% 25℃ 2.350 2.923 3.365 ------

2008 CSBE/SCGAB Annual Conference

Results – Protein content

2008 CSBE/SCGAB Annual Conference

Results – Protein content

2008 CSBE/SCGAB Annual Conference

Results – Protein content

2008 CSBE/SCGAB Annual Conference

The relationships between protein content and moisture content over 0, 1, 2 and 4 months’ storage could be represented by the following equations:

cc M.-.P 2020 27700

cc M.-.P 2030 27301

cc M.-.P 5750 30602

cc M.-.P 5030 29604

(R2 = 0.88)

(R2 = 1.00)

(R2 = 1.00)

(R2 = 0.99)

Conclusions Considering moisture content only, the 100-seed weight

and the cooking time of red lentil increased in the moisture content range; while the ability of water absorption, dehulling efficiency, and protein content decreased in the moisture content range.

Considering postharvest treatment and storage time, the protein content of red lentil stored at 5 , 100-seed ℃weight, water absorption, and dehulling efficiency decreased within the storage period, while positive trends in the protein content for the red lentil stored at 25 and ℃the cooking time were found during the storage period.

High temperature and long storage time adversely affect the dehulling quality and cooking quality of red lentil.

2008 CSBE/SCGAB Annual Conference

Conclusions Further studies should be conducted on more

variability of chemical and nutritional properties under different postharvest treatments and different storage time, such as the contents of starch, phytic acid, and calcium, to better understand the influence factors on cooking quality of red lentil. Also a wider moisture range and longer storage time should be involved in further studies.

2008 CSBE/SCGAB Annual Conference

Thank you!2008 CSBE/SCGAB Annual Conference