EFFECT OF TECHNOLOGICAL PROCESSES ON

© by PSP Volume 18 – No 10a. 2009

Fresenius Environmental Bulletin

EFFECT OF TECHNOLOGICAL PROCESSES ON THE RELEASE OF COPPER, IRON AND ZINC FROM LUPINE GRAIN PREPARATIONS (Lupinus albus Butan var.) IN IN VITRO ENZYMATIC DIGESTION Zbigniew Krejpcio1*, Eleonora Lampart-Szczapa2, Joanna Suliburska1, Rafał W. Wójciak1 and Anna Hoffman2 1

Department of Hygiene and Human Nutrition, University of Life Sciences in Poznan Wojska Polskiego 31, 60-624 Poznan, Poland 2 Department of Chemistry and Food Analysis, University of Life Sciences in Poznan, Mazowiecka 48, 60-623 Poznan, Poland

ABSTRACT The release of Cu, Fe and Zn from lupine grains (whole and dehulled, non-modified, fermented and extruded) of Butan (Lupinus albus) variety was determined. The samples were subjected to enzymatic digestion under in vitro conditions. The content of minerals in lupine grains before and after enzymatic digestion was determined by flame atomic absorption spectrometry. The statistical analysis was carried out employing the STATISTICA software and using the ANOVA test at the significance level of α=0.05. It was found that the release of Fe and Cu was significantly greater, while the release of Zn was lower from dehulled lupin grains vs. whole grains preparation. Extrusion and fermentation followed by extrusion processing, led to a significant increase of the release of Fe from lupine grains preparations. Fermentation tended to increase the degree of Zn release from lupine grains.

However, the leguminous grains also contain antinutritional factors, such as proteinase inhibitors, lectins, saponins and phytates. Some of these substances may reduce the bioavailability of minerals, either due to formation of extremely insoluble salts, or very poorly dissociated chelates [8]. However, the leguminous grains are not consumed row, but after some technological or culinary processing, which may influence the matrix composition, and in consequence may affect (improve or decrease) mineral bioaccessibility and uptake in animals and humans. A benefit derived from heat and pressure treatment is a partial or total destruction of potentially antinutritional factors, especially protease inhibitors, haemaglutinins, tannins and phytates, which limit bioavailability of minerals [9]. Chemical changes produced by technological or culinary processing could also result in decrease of nutrientive value [8]. The aim of this study was to determine the effect of fermentation and extrusion processing, as well as their combination, on the potential availability of Cu, Fe and Zn from lupine grain (Lupinus albus Butan var.) preparations.

KEYWORDS: lupine, fermentation, extrusion, iron, copper, zinc

MATERIALS AND METHODS

INTRODUCTION One of the most important criteria used for the assessment of food product quality is the quantity and bioavailability of nutrients [1,2]. Products of plant origin, especially cereals and leguminous grains, play an important role in human nutrition. Leguminous plants find application in numerous branches of food industry. In Poland, lupine is a good alternative for soybean. Lupine grains contain significant amounts of protein, fat, minerals and dietary fiber [3-5]. In addition to these nutritional properties, lupine also features beneficial functional properties such as antioxidant, antimicrobial or hypocholesterolaemic effects [6,7].

The experimental material comprised lupine grains of Butan (Lupinus albus) (whole and dehulled, non-modified, fermented and extruded) grown in Poland. Lupine grains were ground under laboratory conditions with a Rekord impact mill and divided with proper sieves into fractions with particles having maximal diameters below 2 mm. Process of fermentation relied on lactic acid fermentation performed by strains of Leuconostoc mesenteroides, Lactobacillus plantarum, Lactobacillus brevis bacteria at 370C for 20-24 h at moisture 60%, range of pH: 4.0 – 4.2. Process of extrusion was performed in the snail extruder Krupp Werner & Pheidere type ZSK 25P.8.2, at moisture 35% and temperature in successive parts of the extruder: 95/120/140/1300C.

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The Cu, Fe and Zn content in the grain samples was determined after dry ashing in 4500C. The Fe, Cu and Zn contents were determined by the flame ASA method using the Zeiss AAS-3 spectrophotometer with BC. The accuracy of the method was established on the basis of the simultaneous analysis of the reference material (CTA-VTL-2, Virginia Tobacco Leaves, Poland) that reached: 96.7%, 102.2% and 94.2% for Fe, Cu and Zn, respectively. The in vitro sample digestion was conducted by the method described by Skibniewska et al. [10] with appropriate modifications. The comminuted sample (2 g) was mixed for 10 minutes with 20 cm-3 deionised water. The solution was brought to pH=2 using 0.1 mol⋅ dm-3 HCL and pepsin solution (16 g pepsin in 100 cm-3 0.1 mol⋅dm-3 HCl) in the amount of 0.5 cm-3 per 100 cm-3. The homogenate was added to the sample which was then incubated for 2 h at the temperature of 370C shaking it in a water bath. The homogenate’s pH was controlled throughout the incubation process correcting it with 6 mol⋅dm-3 HCl. After the incubation the pH of the solution was brought to the level of 6.8-7.0 using 6% NaHCO3 and then a solution of pancreatin was added (4 g pancreatin in l dm-3 0.1 mol⋅dm-3 NaHCO3) in the amount of 10 cm-3 per 40 cm-3 of the sample and incubated for 4 h. The digested sample was filtered through a filter into quartz flasks. The supernatant was mineralized with concentrated 10 cm-3 nitric acid (Suprapure, Merck) and 5 cm-3 perchloric acid (Suprapure, Merck) in a heating bloc (Mineralizator TH2 digital). The statistical analysis was carried out employing the STATISTICA software and using the multivariate ANOVA test at the significance level of α=0.05. RESULTS AND DISCUSSION Processing methods tended to modify the composition and availability of minerals from lupine grains. Table 1 shows the content of minerals before and after technological modifications of lupine grains. It was found that fermentation, extrusion and their combination

significantly increased the content of Cu, Fe and Zn the dehulled lupine grains, while in the case of the whole lupine grains such trend was less pronounced. Table 2 shows the effect of technological processing on the release of Cu, Fe and Zn from the whole and dehulled lupine grains. It was also found that the dehulled lupine grain preparations released significantly higher amounts of Cu (by 27%) and Fe (by 35%), while markedly lower amounts of Zn (by 35%), in comparison with the whole grains, independently on technological processing applied. Similar effect was also observed in our previous studies [11,12,15] for lupine grains of Juno and Baron var. This is probably due to the higher content of phytates, tannins and fibre in whole grains that have strong affinity to bind minerals, depressing their liberation during in vitro enzymatic digestion [13]. Gasiorowski [14] found that some hydrated fibre fractions may reduce the rate of interaction between enzymes and foods which could also be a factor responsible for poor digestibility of nutrients from leguminous and cereal grains. Rahman et al. [15] reported that plant proteins, apart from phytates and fibre, can play an important role in binding minerals in lupine grains. As can be seen from Table 2, fermentation processing markedly increased the degree of Zn release (by 81%), slightly elevated the Fe liberation, while did not affect the Cu release from the lupine grains. Extrusion processing significantly increased the Fe release (by 84%), slightly enhanced the Zn and Cu releases from the lupine grains. Fermentation together with extrusion processing significantly increased the Fe release (by 127%), whereas slightly decreased the Zn and Cu liberation from the lupine grains. These changes seem to confirm that fermentation increases the activity of phytase, while extrusion (high temperature and pressure) disintegrate insoluble organic complexes with minerals [16]. Moreover heat treatment may reorganise dietary fibre components changing their chelating properties. Brzozowska [17] reported that fermenta-

TABLE 1 - Mean content of minerals in lupine grains. element

Cu (mg/100g d.w.)

Fe (mg/100g d.w.)

Zn (mg/100g d.w.)

3.47 ± 0.11c 3.93 ± 0.67c 8.34 ±0.29a 5.08 ± 0.18b

4.99 ± 0.08 4.77 ± 0.96 5.83 ± 0.29 5.37 ± 0.45

3.12 ± 0.22c 4.56 ± 0.58b 5.99 ± 0.22a 5.47 ± 0.33ab

5.10 ± 0.19b 6.28 ± 0.25a 6.74 ± 0.51a 6.58 ± 0.49a

sample without modification after fermentation after extrusion after fermentation and extrusion without modification after fermentation after extrusion after fermentation and extrusion

whole grains 0.54 ± 0.03b 0.62 ± 0.04ab 0.71 ± 0.07a 0.59 ± 0.05ab dehulled grains 0.44 ± 0.01b 0.71 ± 0.01a 0.73 ± 0.02a 0.70 ± 0.01a

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TABLE 2 - Influence of experimental factors on the release of minerals from lupine grains (ANOVA). Experimental factors

Cu r (%) 43.01b 54.84a

Level of factor A1

A. Kind of lupine grains preparation

B. Technological process

A2

(+27.5%)

B1

49.58

B2

44.33

B3

55.99

B4

45.82

Fe r(%) 16.56b 22.34a

Zn r (%) 30.84a 19.99b

(+34.9%)

(-35.2%)

11.45b 19.33ab

20.36b 36.87a

21.05a (+83.8%)

25.95a

(+126.6%)

(+81.1%)

24.69b 19.74b

A1B1 50.00ab 11.33b 21.27c A1B2 28.53c 17.57b 52.41a A1B3 62.06a 18.05b 35.99b A1B4 31.46c 19.24ab 13.66d C. Interaction A x B A2B1 49.15ab 11.58b 19.45c a ab A2B2 60.12 21.08 21.34c A2B3 49.91ab 24.06ab 13.39d 60.18a 32.66a 25.82bc A2B4 A1-whole grains, A2-dehulled grains, B1-without modification, B2- fermentation, B3- extrusion; B4-fermentation and extrusion; p