Developing Functional Foods Using Red Palm Olein: Pilot-Scale Studies

Abstract

Red palm olein (RPOL) is newly developed edible oil rich in phytonutrients like vitamin E, carotenoids, ubiquinones, and sterols. Red palm olein and red palm shortening (RPS), when used in the pilot-scale production of extruded snacks, digestive biscuits and pan bread, enhanced the foods' contents of these health-promoting phytochemicals. The antioxidant provitamin A (β-carotene) contents in snacks and digestive biscuits made with RPOL and RPS ranged from 456.3 to 495.9 and 308.3 to 337.8 mg kg⁻¹ fat, respectively. In comparison, the β-carotene contents in snacks made with control palm oil and/or shortening were extremely low, ranging from 10.4 to 62.4 and for digestive biscuits only 12.0 mg kg⁻¹ fat. The results of this study indicate, that antioxidant-rich functional foods such as bread, biscuits, and extruded snacks can be produced using RPOL and RPS.

Keywords:

• Functional foods
• Carotenes
• Chemical composition
• Antioxidants
• Extrusion
• Biscuits
• Snacks

Introduction

Red palm olein (RPOL) is one of the richest and safest sources of some of the important phytochemicals like vitamin E, carotenoids, ubiquinones, and sterols in the human diet.1 The major components of carotenoids (e.g., α- and β-carotenes) and vitamin E (tocotrienol isomers) are the most important known antioxidant nutrients in our diet,2 which protect us from the damaging onslaught of free radicals. These phytochemicals can play a role in the prevention of cancer as well as other chronic diseases like arthritis, prostrate cancer, coronary heart disease, osteoporosis, and possibly many other diseases.3 Free-radical-mediated lipid peroxidation is also implicated in a variety of pathological conditions, especially in both the initiation and promotion of atherosclerosis.4 Recently, heart disease took over as the world's leading cause of death. Obesity among the affluent strata of societies is another health risk factor that may become a part of this global epidemic.5 Heart disease has been ranked first by the European food marketers, followed by cancer, obesity, osteoporosis, gut health, and immunity, for the promotion of functional foods.6 Maintaining healthy eyesight is a golden standard for consumers. Vision problems are the fourth-fastest growing area being tackled by consumers by self-treatment through functional foods.7 About 75% of the optometrists are aware of the link between the intake of carotenoid pigments (especially lutein, β-carotene, and zeaxanthin), and eye health.8

The major health concerns for the Americans are heart disease, followed by cancer, hypertension, high cholesterol, and joint pain.9 Recently, a widespread belief exists among consumers that eating health-promoting foods is a better way to manage illness than medication. This trend has sent the demand for fortified, functional, and medicinal foods soaring, with the global industry hitting US $50 billion in sales for functional foods.10 From crackers to crisps, the functional food market is exploding. Isoflavones-rich soy germ can be used in baked products, muesli, and granola bars.11 Phytoestrogen-rich flaxseed is a popular ingredient for use in various functional foods such as cereals, pancakes, muffins, pizza, and bread.12 Blueberries, raspberries, blackberries, and strawberries are very high in antioxidant quality, much higher than most common vegetables such as kale and spinach. Muffins baked with these berries are now becoming very popular functional foods.13 For the last five year, the fastest growing categories of functional foods were expected to be snacks and candy (60%), cereals (54%), dairy (44%), and frozen (40%) products.14

Health sells in the food industry, as more people now want to take control of their own health. Functional foods offer the best opportunity to achieve this. Functional snack food is another fast-growing area with a tremendous potential in the coming years. All ages are interested in eating healthy snacks. From crackers to crisps, the functional snack market is exploding and will reach US $4.8 billion by the year 2010.15

The food industry has both a greater challenge and a greater potential to produce nutrient-enhanced, heart-healthy, low-calorie, energizing, anti-arthritic, eyesight boosting, and even dental-care functional foods for the fast-paced consumers of this century. The major objective of this study was to develop antioxidant-rich functional foods such as bread, digestive biscuits and extruded snacks on a pilot-scale, using vitamin E- and carotenes-rich RPOL and red palm shortening (RPS).

Materials and Methods

Raw Materials

Red palm shortening and RPOL were provided free of charge by the Carotino Company of Malaysia. For the pilot-scale production of the bakery products, white flour (72% extraction), whole-wheat flour, fine bran, fine granulated sugar, common salt, bakery shortening, chemical leavening agents, instant dry yeast, nonfat dry milk, raw materials for extruded snacks (e.g., corn grits, soy grits, cheese, colorings, and flavorings etc.) and the required packaging materials were supplied by the collaborating company in Kuwait.

Bread-Making

Pan bread was produced in a commercial bakery using white flour as well as whole-wheat flour, instant dry yeast, sugar, shortening, salt, supergama as improver (Zeelandia, Holland) and sodium stearoyl-2-lactylate (SSL) as emulsifier (American Ingredients Co., Kansas City, US). The water absorption used for white bread, brown bread, and whole-wheat bread making were 55, 57, and 57 kg water/100 kg flour, respectively. The moisture contents of white flour dough and whole wheat flour dough before baking were 46.7 and 51.2%, respectively. These ingredients were mixed to a final dough temperature of 30°C. The mixed dough was left to rest at room temperature (22±2°C) for 45 min and then divided into 580-g pieces, molded and put in pans. It was proofed for about 45 min at 35°C and 75% relative humidity. After proofing, the bread was baked in a rotary oven at 200°C for 50 min. The bread was cooled to room temperature, sliced, and packaged in polyethylene bags. These bread samples were transported to laboratories at the Kuwait Institute for Scientific Research (KISR) for further chemical and sensory analyses during the storage period of 5 days at room temperature.

Digestive Biscuits Making

Three types of digestive biscuits were prepared in a commercial biscuit plant using 45 parts of whole-wheat flour (12.8% moisture content) and 55 parts of biscuit flour (12.3% moisture content). Other ingredients like hydrogenated palm oil, butter, sugar, liquid glucose, malt flour, whey powder, emulsifier (soy lecithin), salt, sodium bicarbonate, and ammonium bicarbonate, were measured based on total flour. Control shortening was completely replaced with RPS in sample no. 2, where as in sample no. 3, equal parts of RPS and RPOL were used in place of the control shortening. Biscuits were deposited on a conveyor belt using a rotary molder, baked in an electrically heated oven for about 8 min at a temperature gradient of 195→225→215→195°C during the four baking temperature zones. Biscuits were cooled to room temperature and packaged in small units of two biscuits (19.5 g) as well as larger packs of 18 biscuits (165 g) using biaxially oriented polypropylene (BOPP) metalized film. The prepared biscuit samples were transported to KISR's laboratories for chemical and sensory analyses during the storage period of 6 months at room temperature (22±2°C).

Extruded Snacks

Corn-grits-based extruded snacks were produced in two commercial plants. The control snacks were prepared using refined bleached deodorized palm oil (RBDPO), whereas in the experimental snacks, RPOL was used in place of RBDPO. The corn grits were extruded under high shear force in a single-screw extruder (Lallesse Maschinebau, Arnhen, The Netherlands) and then dried to a suitable moisture content (∼1–2%). A slurry consisting of palm oil, cheese, flavoring agents, salt, and coloring matter was sprayed onto these extruded snacks at a temperature of 22°C and packaged in BOPP (about 20 g) using automatic packing machines. In experimental samples, coloring matter was not used, as the RPOL had sufficient yellow color of its own due to the presence of β-carotenes. The prepared and packaged snacks were transported to KISR's laboratories for chemical and sensory analyses during the storage period of 6 months at room temperature.

Chemical Analysis

The bread samples were freeze-dried and powdered in a Falling Number Mill (model 3100, Sweden) to pass through a 100-mesh sieve, and stored in airtight containers in a refrigerator for further chemical analysis. The digestive biscuits and snack samples were directly ground, as they had very low moisture contents (∼1–2%), and stored in airtight containers for further chemical analysis. All of the bread, digestive biscuit, and snack samples were analyzed for proximate composition (moisture, protein, ash, and fat) using standard American Association of Cereal Chemists methods.16 The results obtained are expressed on a moisture-free basis. The nitrogen content determined by the Kjeldahl method was converted into protein content using a conversion factor of N×5.70 for bread and digestive biscuits, and a factor of N×6.25 for extruded snacks. All analyses were done in triplicate, and the average values are presented here.

The β-carotene content was estimated as per the Palm Oil Research Institute of Malaysia's procedure.17 Lipids were extracted by the method of Bligh and Dyer18 and were analyzed, in duplicate, for fatty acid profiles. The fatty acid compositions of RPOL and RPS were determined by the standard Association of Official Analytical Chemists method as described by Aziz and Abu-Dagga.19 Gas chromatographic conditions for fatty acid analysis were as follows: an injection port temperature of 250°C, a detector temperature of 260°C, an initial oven temperature of 140°C, a final oven temperature of 210°C, a program rate of 2°C min⁻¹, a final time of 15 min, a column-fused silica capillary coated with OV-225, 25×0.2-mm, carrier gas flow/nitrogen 2 mL min⁻¹, a split ratio of 1:30, and an injection volume of 1 µL.

Objective Color Measurements

The objective color of extruded snacks and digestive biscuits was measured with a Macbeth Color checker (model 545, Kollmorgen Instruments Corp., UK) portable spectrophotometer as CIE L* a* b*. Under this tristimulus color coordinate system, the L* value is a measure of lightness and varies from 0 (black) to 100 (white); the a* value varies from −100 (green) to +100 (red); and the b* value varies from −100 (blue) to +100 (yellow). As the values of a* and b* rise, the color becomes more saturated or chromatic, but these values approach zero for neutral colors (white, gray or black). The instrument settings were Illuminant D50, Display L* a* b*, Observer 2°, and were calibrated with a white primary tile supplied by the manufacturer. Twelve readings were taken on the surface of biscuits and extruded snacks. After discarding the two most extreme readings, the remaining 10 were averaged and are reported.

Additional color attributes like whiteness value, redness index (RI), saturation index (SI), were also calculated from the CIE L* a* b* values as per the procedure reported earlier.20 The whiteness value was calculated by the equation: 100 − [(100−L*)²+a*²+b*²]^1/2 is a measure of lightness. The a*/b* ratio was used as an index of apparent change in redness. The SI, which represents the color intensity, color purity or chroma in a sample, was calculated by the equation: (a*²+b*²)^1/2.

Statistical Analysis

All of the chemical analyses were reported on a moisture-free basis. All data obtained were analyzed statistically for analysis of variance, and the mean values were evaluated for statistical significance (P=0.05) using Duncan's New Multiple Range Test (SAS Program, Windows Version 6.08). Inferences were reported at the appropriate places. Significance was accepted at the P=0.05 level. For the results of the chemical analyses, the mean values are reported.

Results and Discussion

Chemical Analyses

Digestive biscuits, corn-based extruded snacks, and three different types of bread (whole-wheat bread, white bread, and brown bread) were prepared on a pilot scale in three local commercial plants using RPS and RPOL. After proper packaging, these products were transported to KISR laboratories for further chemical analysis and the results are reported here.

Extruded Snacks

The extruded snacks made in two commercial plants differed slightly in protein and fat contents, probably because of the type and amount of cheese used as well as the other raw materials (mainly corn grits and amount of oil used in slurry), but these differences were statistically insignificant (P=0.05) only for the fat contents between these two plants. Among the snacks from these two plants, the protein, ash, and fat contents ranged from 4.67 to 6.04%, 1.70 to 2.93%, and 35.67 to 41.29%, respectively (Table 1). Snacks from plant no. 1 had a slightly higher protein content (5.31–6.04%) than those from plant no. 2 (4.67–4.88%) but a lower fat content (35.67–37.50%) than those from plant no. 2 (39.56–41.29%). The ash content in these snacks ranged from 1.70 to 2.93%, with a significantly lower value in test snack from plant no. 1. Among the control and test snacks in any of the plants, no significant differences were observed in these constituents, except the β-carotene. The β-carotene contents in snacks made with RPOL were significantly higher (456.3–495.9 mg kg⁻¹ fat) than those in the control snacks (10.4–62.8 mg kg⁻¹ fat). The higher levels of these anti-oxidant vitamins in test snacks as compared with control, justify the use of RPOL in producing such nutritious snacks. These types of functional snacks are becoming popular not only among children but also among adults.15 They, therefore, could serve as a good source of antioxidant β-carotene in the diet. Snacking behavior among the various sections of society is continually increasing, and both the adults as well as children are making efforts to eat healthy snacks. Snacks prepared with RPOL will not only supply proteins, fats, and minerals but also the much needed antioxidants like vitamin E and β-carotene.

Table 1 Chemical composition of extruded snack samples made with RPOL in two commercial food plants

Sample description	Proteina (N×6.25) (%)	Asha (%)	Fata (%)	β-Caroteneb (mg kg^−1 fat)	Moisture content (%) (as-is-basis)c
Control shorteningd	5.31g	2.93a	37.50c	10.4e	1.4
RPOLd	6.04g	1.70b	35.67c	456.3f	1.6
Control shorteninge	4.67g	2.06a	41.29d	62.8e	1.3
RPOLe	4.88g	2.56a	39.56d	495.9f	1.1

Note: For comparison among the four snack samples, protein, ash, fat, and β-carotene values with same letters in a single column do not differ significantly (P=0.05).

^aOn a dry basis.

^bIn extracted fat.

^cInitial moisture content of corn grits was 12.8%.

^dExtruded snacks made in plant no. 1.

^eExtruded snacks made in plant no. 2.

Digestive Biscuits

For the preparation of biscuit samples in a commercial plant, digestive biscuits were chosen, simply because they were the most popular type of biscuits consumed by the local people. Moreover, this product (digestive biscuits) resembles more closely the sugar-snap cookies than any other biscuit being produced here locally. In the production of digestive biscuits, white flour and whole-wheat flour were used in ratios of 55:45 parts, respectively. The original digestive biscuits being produced by the commercial plant were taken as the control; however, two additional test samples were prepared commercially by replacing normal shortening with RPS alone in one, and RPS and RPOL in equal combinations in the other. Among the three digestive biscuit samples from this commercial plant, the protein, ash, and fat contents ranged from 6.94 to 7.09%, 1.47 to 1.51%, and 21.51 to 22.37%, respectively (Table 2) and did not differ significantly among each other (P=0.05). The higher ash contents in these digestive biscuits than the other soft-dough biscuits came mainly from the 45% whole-wheat flour used in the formulations, as the bran components present in whole-wheat flour are known to be richer in mineral content.21 The digestive biscuits made with RPS, or the RPOL:RPS combinations were significantly richer in β-carotene (308.3–337.8 mg kg⁻¹ fat) than the control biscuits (12.0 mg kg⁻¹ fat). Red palm olein and RPS can, therefore, serve as a good source of β-carotene if used in the preparation of digestive biscuits on a commercial scale. Digestive biscuits, being rich in fat, would improve the supply of much needed antioxidants in the diet of consumers.

Table 2 Chemical composition of digestive biscuit samples made with RPS and RPOL in a commercial food plant

Sample description	Proteina (N×6.26) (%)	Asha (%)	Fata (%)	β-Carotene (mg kg^−1 fat)	Moisture content (%) (as-is-basis)
Control shorteningb	6.94a	1.47b	21.92c	12.0d	1.1
RPSc	7.05a	1.49b	22.37c	308.3e	1.1
RPS+RPOL (1:1)d	7.09a	1.51b	21.51c	337.8e	0.8

Note: Initial moisture content of biscuit dough was 20.3%. For comparison among the three digestive biscuit samples, protein, ash, fat, and β-carotene values with same letters in a single column do not differ significantly (P=0.05).

^aOn a dry basis.

^bDigestive biscuits made with control shortening.

^cDigestive biscuits made with RPS.

^dDigestive biscuits made with RPS:RPOL.

Pan Bread

Whole-wheat bread, white bread, and brown bread prepared on a pilot scale using RPS and RPOL, were analyzed for protein, fat, ash, and β-carotene contents, and the results are presented in Table 3. For the whole-wheat bread protein, fat, and ash contents ranged from 10.97 to 11.21, from 4.46 to 6.82, and from 2.56 to 2.96%, respectively. These values for protein, fat, and ash were quite comparable to those of brown bread reported in the literature.22 23 24 The protein, fat, and ash contents were lower in white bread, ranging from 10.41 to 10.46, from 2.97 to 4.10 and from 1.41 to 1.53%, respectively. The moisture content of white bread and whole wheat flour bread after baking and cooling were 32.8% and 38.1%, respectively. The bran and germ constituents present in whole-wheat flour and brown flour are known to be richer in protein, fat, and ash contents than the inner endosperm of the wheat kernel, which explains about the higher values in the whole-wheat and brown bread samples.21 25

Table 3 Proximate analysis and total β-carotene content of pilot-scale trial bread samples

	Proximate composition (on a dry basis)			β-Carotene content (mg kg^−1 fat)
Bread sample	Proteina (%)	Fat (%)	Ash (%)	Time zero	5 d
Whole-wheat bread control	11.12a	4.46bc	2.66ab	56.4ga	37.9rb
Whole-wheat bread with RPS	11.21a	4.86b	2.56abc	136.0ec	123.4pd
Whole-wheat bread with RPS:RPOL	10.97c	6.82a	2.96a	169.3fe	154.7nf
White bread control	10.41b	3.69d	1.49d	42.3hg	30.8th
White bread with RPS	10.45b	4.10c	1.53d	159.3cj	142.5qk
White bread with RPS:RPOL	10.46b	2.97e	1.41d	250.0am	222.4jn
Brown bread control	11.37a	4.32c	1.96cd	53.2gp	38.8rq
Brown bread with RPS	11.14a	4.99b	2.40abc	177.6ds	166.8mt
Brown bread with RPS:RPOL	10.83c	3.71d	2.23bc	188.5bw	181.0ky

Note: RPS, red palm shortening; RPOL, red palm olein. For comparison among the nine bread samples, protein, fat, ash, and β-carotene values with same letters in a single column do not differ significantly. Among the nine bread samples at zero and five days, β-carotene values with different subscripts differ significantly (P=0.05).

^aProtein, N×5.70.

The β-carotene contents of fat extracted from bread samples were quite low (Table 3), compared with those from extruded snacks and biscuits (Tables 1 and 2). The shorter baking time of 8 min used for biscuits, compared with 24 min for bread, may be responsible for the better retention of β-carotenes in the biscuits. As the flavor and fat mixture is applied to the extruded snacks at the end of the processing line just before packaging, obviously very little destruction of these β-carotenes is expected. Biscuits and extruded snacks had a much higher fat content than bread, so the former would be an excellent carrier for the important antioxidants (β-carotenes) than the pan bread.

Fatty Acid Composition

The manufacture of extruded snacks involves a step in which a slurry of flavor, color, and other additives are sprayed onto the product just before the finishing stage; palm oil is used as a base for such additives. Since both the control snack and test samples had palm oil in the slurry, no significant differences were observed in their fatty acid composition (Table 4). Oleic acid and palmitic acid were the predominant unsaturated and saturated fatty acids in these snacks, respectively. Very similar trends were observed in the fatty acid composition of fat from digestive biscuit samples prepared in the commercial food plant no. 2 (Table 5). Oleic acid and palmitic acid were also the predominant unsaturated and saturated fatty acids in these biscuits, respectively. The linolenic acid level in these biscuits was less than 1%. The unsaturated fatty acid content of biscuits made with a combination of RPS and RPOL was slightly higher than that of both the control and the sample made with 100% RPS. Among the fatty acids in various bread samples, palmitic, oleic, and linoleic acids were predominant (Table 6).

Table 4 Fatty acid composition of fat extracted from extruded snack samples made with RPOL in two commercial plants

		Fatty acid content (wt.% of methyl esters)
Type of fatty acid	Fatty acid	Control snacka	Test snacka	Control snackb	Test snackb
Saturated	C12	0.35	0.51	0.74	0.45
	C14	1.25	1.64	1.43	1.44
	C16	39.95	38.54	39.50	38.47
	C18	4.43	4.48	4.39	4.25
	C20	0.39	0.39	0.38	0.37
Unsaturated	C18:1	42.47	42.29	42.38	42.45
	C18:2	10.89	11.84	10.92	12.22
	C18:3	0.28	0.33	0.28	0.36

^aExtruded snacks made in plant no. 1.

^bExtruded snacks made in plant no. 2.

Table 5 Fatty acid composition of fat extracted from digestive biscuit samples made with RPOL, RPS, and control shortening in plant no. 2

		Fatty acid content (wt.% of methyl esters)
Type of fatty acid	Fatty acid	Control biscuits	RPS digestive biscuits	RPS+RPOL digestive biscuits
Saturated	C12	0.54	0.51	0.56
	C14	2.19	1.71	1.84
	C16	48.84	46.20	43.39
	C18	4.43	4.71	4.49
	C20	0.46	0.36	0.37
Unsaturated	C18:1	33.06	36.16	37.93
	C18:2	9.45	10.01	11.06
	C18:3	0.33	0.37	0.37

Table 6 Fatty acid composition of extracted fat from various optimized bread formulations made on a pilot scale in a commercial bakery

Fatty acids	Control whole-wheat bread	Whole-wheat bread with RPS	Whole-wheat bread with RPS:RPOL	Control white bread	White bread with RPS	White bread with RPS:RPOL	Control brown breada	Brown breada with RPS	Brown breada with RPS:RPOL
C8	0.02	0.02	0.18	0.03	0.03	0.03	0.02	0.12	0.01
C10	0.03	0.02	0.04	0.03	0.03	0.03	0.02	0.03	0.03
C12	0.20	0.21	0.21	0.18	0.20	0.25	0.17	0.23	0.27
C14	0.95	0.85	0.82	0.85	0.87	0.90	0.80	0.94	0.96
C15	0.08	0.06	0.07	0.07	0.31	0.06	0.03	0.07	0.05
C16	41.22	38.50	34.63	39.25	39.80	37.17	38.47	38.45	37.50
C16:1	0.20	0.19	0.18	0.19	0.17	0.21	0.23	0.23	0.22
C17	0.12	0.12	0.13	0.12	0.12	0.12	0.12	0.11	0.10
C18	4.40	4.35	5.65	5.30	4.90	4.30	4.40	4.17	4.10
C18:1	31.02	33.45	39.10	33.85	36.73	32.92	31.25	33.88	41.50
C18:2	19.94	20.50	17.55	18.65	15.65	22.47	22.57	20.20	17.00
C20	0.35	0.37	0.39	0.36	0.40	0.34	0.33	0.34	0.35
C18:3	0.31	0.38	0.34	0.51	0.62	1.10	1.15	1.50	1.10
C20:1	1.17	1.12	0.93	0.64	0.45	0.79	0.48	0.49	—

Note: Amounts are given as wt.% methyl esters. RPS, red palm shortening; RPOL, red palm olein.

^aBrown bread was made with white flour and 20% fine bran.

Objective Color of Extruded Snacks and Digestive Biscuits

Red palm olein and RPS, being rich in β-carotenes, were expected to impart a desirable natural yellow color to the extruded snacks as well as digestive biscuits. The objective color of outside surfaces of extruded snacks and digestive biscuits was, therefore, measured using the tristimulus CIE L* a* b* system with a Macbeth Color checker spectrophotometer. Based on the CIE L* a* b* values, various color properties, i.e., whiteness, RI and SI, were calculated for the extruded snacks and digestive biscuits, and these results are also presented in Tables 7 and 8. Significant differences were observed in the L*, a*, and b* values among the control and test snack samples made in both the commercial plants (Table 7). L* values of the control snacks from both the plants did not differ significantly and so was in the case of test snacks from these plants. The a* values for both the control as well as test snacks did not differ within the same plant but differed significantly among the plants. The reason for higher a* values (i.e., brown color) of snacks from plant no. 2, may be the use of paprika (brown colored) as flavoring agent. The test snacks made with β-carotene rich RPOL were significantly darker in yellow color (higher b* values) than the control snacks made with normal palm oil in both the plants. Expectedly, the use of RPOL imparted a desirable natural yellow color to the test snacks, which was reflected in the higher b* values. The higher SI or chroma values in test snacks indicates that the use of β-carotene rich RPOL enhanced the purity or saturation of yellow color for these test samples.

Table 7 Effect of RPOL and RPS on the CIE L* a* b* values and the color attributes of extruded snacks prepared on a pilot scale

Sample description	L*	a*	b*	Whiteness value	RI	SI
Plant no. 1
Control snacks	57.9a±2.8	9.3c±1.4	35.2e±1.8	44.34	0.26	36.40
Test snacks	49.5b±4.9	8.9c±1.3	62.1f±3.8	19.46	0.14	62.73
Plant no. 2
Control snacks	56.7a±5.7	10.8d±1.4	41.2g±2.8	39.26	0.26	42.59
Test snacks	47.8b±3.6	11.4d±1.2	56.6k±3.5	22.16	0.20	57.74

Note: L* is a measure of lightness and varies from 0 (black) to 100 (white); the a* value varies from −100 (green) to +100 (red); and the b* value varies from −100 (blue) to +100 (yellow). As the values of a* and b* rise, the color becomes more saturated or chromatic, but these values approach zero for neutral colors (white, gray or black). Whiteness 100−[(100−L*)²+ a*²+b*²]^1/2 is a measure of lightness. Redness Index (RI)—index of apparent change in redness=a*/b* ratio, Saturation Index (SI) or chroma=(a*²+b*²)^1/2. Mean values in a column with different letters differ significantly (P=0.05).

Similarly, the use of β-carotene rich RPOL in digestive biscuits resulted in significantly higher L*, a*, and b* values in test samples than in the control, indicating the darker yellow color of these test samples (Table 8). Maillard reactions during baking of biscuits produced slight but significant change in the browning of test biscuits, that is evident from the higher a* values (15.9–19.0) compared with the control biscuits (12.3). The significantly higher b* values for test biscuit samples indicate the darker yellow color imparted to these products by the β-carotene rich RPOL and/or RPS than the control biscuits. The wheat flour used in biscuits has certain amount of naturally occurring carotenoid pigments, which impart this yellow color,20 but the RPOL and RPS being very high these carotenoid pigments imparted distinct yellow color to the test biscuits. The results show that the addition of RPOL or RPS significantly affected the whiteness value in test products as these became darker in color. Compared with control biscuits (40.7), higher SI or chroma values for the test samples (70.3–72.4) were observed. The carotenoid pigments present in RPOL and RPS contributed to the enhanced saturation of the yellow hue in these functional foods.

Table 8 Effect of RPOL and RPS on the CIE L* a* b* values and the color attributes of digestive biscuits prepared on a pilot scale

Sample description	L*	a*	b*	Whiteness value	RI	SI
Plant no. 2
Control biscuits	74.9a±0.6	12.3d±0.6	38.8g±0.5	54.60	0.32	40.70
Test biscuits with RPS	73.6b±1.5	15.9e±0.8	68.5j±0.9	24.89	0.23	70.32
Test biscuits with RPS:RPOL	66.3c±2.8	19.0f±0.4	62.9k±1.5	20.11	0.27	72.44

Note: L* is a measure of lightness and varies from 0 (black) to 100 (white); the a* value varies from −100 (green) to +100 (red); and the b* value varies from −100 (blue) to +100 (yellow). As the values of a* and b* rise, the color becomes more saturated or chromatic, but these values approach zero for neutral colors (white, gray or black). Whiteness 100−[(100−L*)²+a*²+b*²]^1/2is a measure of lightness. Redness Index (RI)—index of apparent change in redness=a*/b* ratio, Saturation Index (SI) or chroma=(a*²+b*²)^1/2. Mean values in a column with different letters differ significantly (P=0.05).

Conclusions

The results of this study indicate a strong possibility for producing extruded snacks and digestive biscuits on a commercial scale using RPOL and RPS. Red palm olein and RPS, being rich in β-carotenes and other phytonutrients, if used in product development, would increase the nutritional contributions of these functional foods in terms of meeting our requirements for these health-promoting antioxidant vitamins in our normal diet.

Acknowledgments

The authors express their gratitude to the managements of the KISR and the Malaysian Palm Oil Board for their financial support of and encouragement to execute this research. We also thank the Carotino Company, Malaysia, for supplying the red palm oil and RPS samples. Special acknowledgment is given to the Foodstuff Industries Company (FICO) and the Kuwait-Indo Trading Company (KITCO) for utilization of their commercial production facilities in the processing of the test extruded snacks and digestive biscuits. We also thank Mr. Austin D'Souza and his colleagues at Sweet Dalia, Azzad Trading Group, Kuwait, for their assistance as well as permission to use their facilities and materials to prepare bread samples on a commercial scale in their bakery.