Food quality evaluation of an international collection of barley landraces

Transcription

1 576 Food quality evaluation of an international collection of barley landraces A. Jilal, 1 R.J. Henry, 2 L.S. Lee, 2 N, Rice 2 and S. Grando 1 1 International Center for Agricultural Research in the Dry Areas (ICARDA), P.O.Box 5466, Aleppo, Syria. 2 Grain Foods CRC, Centre for Plant Conservation Genetics (CPCG), Southern Cross University, PO Box 157, Lismore NSW 2480, Australia. Abstract Barley has been a staple food since its domestication years ago in the Fertile Crescent. Traditionally, it has been utilized in various ways, particularly in marginal regions, according to the local culture, with typical breads, drinks and dishes often prepared from local barley landraces. This project consists of assessing food quality richness of these landraces through the evaluation of 584 barley landraces from 42 countries, evaluated in two different environments and assessed for several food quality traits. These traits were beta-glucan content (ranging from 4.93 to 7.67%), protein content (7.18 to 20.23%), hardness (very hard to very soft), husk percentage (0 to 46%), aleurone color (white, green, blue or black) and 1000-kernel weight (19.3 to 64.5 g). Principal components analysis associated with 3D categorized plots applied to the landrace data revealed groups with specific quality characteristics associated with specific barley food products. Introduction Historically, barley had a reputation for building strength, and it was used by the gladiators of the Roman Empire in their training diet in the form of bread (pulmentum). It has been the energy food of the masses, especially in regions characterized by harsh living conditions and low-output production systems typical in developing countries. Preferentially, the local landraces are used for traditional recipes (e.g. Aballagh in Morocco, Tsangpa in Tibet, Machica in Ecuador, Gofio in Canary Islands and Giotta in Switzerland). However, barley is still rarely used for food purposes when one compares global production and trade (Figure 1). Since the finding of barley health benefits linked to barley s content of soluble dietary fiber (beta-glucan) that reduces risk of coronary heart disease, elevated blood cholesterol and glucose levels, and reduces obesity via increased satiety, the use of barley grain, rather than wheat and rice (Figure 2), as a food or food ingredient has increased gradually over time in developed countries through the development of various food barley products made from improved varieties. From these products, which are barley flakes, pearl and pot barley, barley grits, waxy barley, hulless barley and barley flour, several dishes and drinks are prepared (porridge, granola, muesli, cookies, muffins, desserts, salads, soups, puddings, stews, casseroles, pancakes, breads, pasta, biscuits, pizza crusts, coffee, tea, etc.). Recipes for several dishes having barley as a main ingredient can be freely obtained online. Barley landraces are the result of natural and farmer selection pressure over many generations and are still preferred to improved varieties for making traditional foods, mainly in harsh regions, because probably the selection was is in favor of food quality. Thus, assessing a collection of international barley landraces to eventually find promising examples for food uses has a major importance.

2 577 Figure 1. Worldwide food barley situation in kg/person/year (FAO Data from

3 578 Grams of fiber/40g serving Figure 2. Amount of fiber and beta-glucan serving per product (Conway, 2007). Materials and methods The 584 barley landraces investigated were from ICARDA s gene bank and represented an international selection of germplasm with various morphological, agronomic and physiological characteristics. They were split into two trials, using spatial analysis for an unreplicated design (Row Column design), and implemented at two of ICARDA s experiment stations (Tel Hadya, a favorable site, and Breda, an unfavorable site). The trials were: Diverse Barley Germplasm (DBG): 246 entries from 42 countries, including 36 accessions of Hordeum spontaneum and 4 improved varieties used as repeated checks. Landrace collection (LAND): 338 landraces from 34 countries, with 4 improved varieties as repeated checks. Sample origin and their number are shown in Figure 3. Several quality parameters have been evaluated for the whole set, namely: husk%, estimated by de-hulling 20 g of barley grains with the barley pearler, 1000-kernel weight (TKW) using grain counting apparatus; aleurone color (Aleur. C.) scored visually from pearled grain; hardness (Hard) by shaking 5 g of barley flour in sieve shaker of 200 mesh sieves; protein content (P%); and beta-glucan content (BG%), extracted from the calibration of Near Infrared spectrometry for this parameter (Table 1). The data were analyzed using spatial analysis for an unreplicated design with Genstat software, and the Best Linear Unbiased Predictors (BLUPs) were calculated. The subsequent statistical Table 1. Range and evaluation tools of the screened quality parameters. Husk % Aleurone TKW Hardness P % BG % color Class 1 <5 Very Low White gvery Small 30 40%Very Hard <9Very Low <5Very Low Class Low Green g Small 41 50% Hard Low Low Class Medium Blue g Medium 51 60% Medium Medium Medium Class High Brown g Large 61 70% Soft High High Class 5 >20 Very High Black > 55 g Very Large > 70% Very Soft Very High Very High Class 6 >17.5 Extra High >7Extra High Visual on pearled barley Sieve shaker with Near Infrared Near Infrared Tools Barley pearler grain Seed counter 200 mesh sieves spectrometry spectrometry

4 579 Figure 3. Origin of barley landraces samples used in the evaluation. analyses were conducted on the BLUPs, using SPSS and PAST for analysis of variance and principal component analysis, while STATISTICA software was used for simultaneously graphing all the quality parameters. Results and discussion The mean values at both experiments stations are shown in Figure 4. As depicted, the mean values for husk percentage and protein content were high on the unfavorable site, unlike TKW. Hardness and betaglucan content differed slightly between the two environments. In the unfavorable environment, less rainfall associated, with high temperature, affected grain filling, which led to low TKW negatively correlated with protein content. High husk percentage values in the raw data were mainly observed in the wild species H. spontaneum. Analysis of variance of the quantitative data of the five quality parameters for LAND and DBG materials showed significant differences between sites for all the quality parameters (Table 2). Based on Table 1, the numbers of samples for class of the quality parameters are presented in Table 3. Out of the 584 samples, 11 samples of LAND material have medium hard kernels, while the rest have hard kernels. Protein content was mostly low to medium in both materials. Beta-glucan content had as values medium, high and very high, and thus favorable for food. With PAST software, the two principal axes of the principal component analysis for LAND and DBG quantitative data (Husk%, Hard, TKW, P% and BG%) explained respectively and 98.13% of the variance (Figures 5 and 6). As shown in Figures 5 and 6, hardness, protein and beta-glucan content grouped together with a significant number of samples far from husk% (undesirable for food consumption). Unfortunately, it is difficult to group the individuals according to their quality parameter class. As all the samples for both DBG and LAND were hard to medium hard, considering the parameter (hardness) as a fixed factor, the 3D categorized plots of STATISTICA software illustrated in Figures 7 and 8 depicted the combination of the five

5 580 Table 2. Analysis of variance of the five quality parameters across sites. LAND material DBG material Dependent Type III Sum of Variable Squares df Mean Square F Sig. Husk% Hardness TKW Protein% beta-glucan% beta-glucan% beta-glucan% Husk% Hardness TKW Protein% beta-glucan% Table 3. Distribution of barley samples according to the appropriate class for LAND and DBG materials. Dependent Type III Sum of Class Aleur. C. Husk% Hard TKW P% BG% Aleur. C. Husk% Hard TKW P% BG% Total Figure 4. Range values of LAND and DBG materials in both Tel Hadya and Breda experiment stations.

6 581 Figure 5. Principal Component Analysis of LAND material. Figure 6. Principal Component Analysis of DBG material.

7 582 Figure 7. Categorized plot of the quality parameters of DBG material. Figure 8. Categorized plot of the quality parameters of LAND material.

8 583 quality parameters (Husk%, Aleur. C. showed as class numbers, TKW, P% and BG%) in order to disclose the appropriate samples suitable for barley products. As an example and according to MacGregor and Bhatty (1993), pearled barley is defined as low husk, medium to hard kernel, TKW of 45 g, white aleurone with a protein content of 10% and 5% of beta-glucan content. We can observe that in the two first graphs in both Figures 7 and 8 (husk<10%), 4 samples respond to the criteria listed above in DBG material and one sample in LAND material. References Conway, J Health benefits of barley: effect of barley consumption on glucose, insulin, and lipid metabolism. Idaho Dietetic Convention, oral presentation. IBC_JoanConway_April2006.pdf Grando, S. & Gomez Macpherson, H. (editors) Food Barley: Importance, Uses and Local Knowledge. Proceedings of the International Workshop on Food Barley Improvement, Hammamet, Tunisia, January ICARDA, Aleppo, Syria. 156 p. MacGregor, A.W. & Bhatty, R.S Barley chemistry and technology. American Association of Cereal Chemists, USA.