Quality Characteristics and Consumer Acceptability of Salt Bread Supplemented with Chili Pepper (Capsicum sp.) Leaves

Abstract

The effect of chili pepper leaves (CPL) on the sensory characteristics, microbial load, consumer acceptability, and nutritional quality of salt bread was evaluated. Crushed and powdered CPLs were used in salt bread at different substitution levels: 0 (control), 0.5, 1, 2, 3 and 4% (wt/wt flour). All sensory attributes of salt breads with 0.5% crushed CPL (CCPL) or powdered CPL (PCPL) were comparable with the control. The consumer acceptability for 0.5% CCPL and PCPL were 97 and 93%, respectively. The use of 0.5% CPL in salt bread boosted the β-carotene content from <1 µg/100 g to up to 238 µg/100 g and significantly increased the folate and iron levels. Water activity values were comparable with the control and microbial counts of the enriched products were within acceptable limits. Results showed that CPL can be incorporated in salt bread as a means to improve iron, vitamin A, and folate nutrition in areas where micronutrient malnutrition is prevalent.

Introduction

Iron, vitamin A, and folate are among the micronutrients deficient in the diet of many people in developing countries. In the Philippines, iron and vitamin A deficiencies remain as public health problems (FNRI, 2013) among children and women (pregnant and lactating). Folate deficiency, which is associated with birth defects, colorectal cancer, and lifelong physical and intellectual disabilities, is also an emerging concern (deVogel et al., 2008; Fujimori et al., 2011). Green leafy vegetables are very rich in essential micronutrients such as vitamin A (in the form of β-carotene), folate, and iron (Ng et al., 2012; Gupta and Prakash, 2011). Being micronutrient-dense, incorporating them in food or dishes as ingredient is one way of ensuring supply of micronutrients in the diet.

Chili pepper (Capsicum sp.) is a popular ingredient in Asian cuisine. In the Philippines, the leaves are usually added in a chicken ginger stew with unripe papaya. The green grassy herby aroma of chili pepper leaves (CPL) gives the dish its distinct taste. CPL imparts milder heat and pungency in foods in comparison to the fruit, and is therefore a perfect substitute for people who are not used to strong spices. The leaves of chili pepper contains significant amount of vitamins and minerals (FNRI, 1997) and capsaicin, which has therapeutic properties (Yaldiz et al., 2010). With its good nutritional profile and phytochemical compounds, CPL is a good candidate as additive in different food preparations.

Pandesal or salt bread is probably the most popular bread in the Philippines and traditionally served for breakfast in a plain roll or complemented with various fillings or hot chocolate, coffee or tea. It is basically made with flour, yeast, egg and milk. One hundred grams of salt bread generally contains 330 calories, 4 g fat, 63 g total carbohydrates and 10 g protein (FNRI, 1997). Since salt bread is eaten by most Filipinos of all ages everyday, it is a perfect vehicle for supplementation. Addition of nutrient-rich indigenous vegetables, such as squash and leafy moringa, in bread has been shown to effectively enhance its nutrient profile (ii, iv, vi).The use of chili pepper leaves as an inexpensive ingredient to boost the nutritional quality of salt bread was therefore investigated. The effects of crushed and powdered form of chili pepper leaves on the salt bread in terms of quality, sensory characteristics, and consumer acceptability were assessed.

Materials and Methods

Sample collection    Leaves of chili pepper (Capsicum sp.) were harvested from Calipahan, Talavera, Nueva Ecija, Philippines during the dry season of 2012. The collected leaf samples were kept in plastic bags and transported to the laboratory for processing on the same day.

Sample preparation    CPL were immediately processed into crushed and powdered forms according to the following procedure: Healthy leaves were selected and thoroughly washed under running potable water, rinsed twice with distilled water, laid in sterile trays, air-dried for several minutes, and oven-dried at 40°C for 12 h. The dried leaves were crushed manually for the crushed CPL (CCPL) and passed through a 425-µm mesh sieve for the powdered sample (PCPL).

Optimization of salt bread formulation    Preparation of salt bread was conducted at KN Bakery & General Merchandise at Bantug, Science City of Muñoz, Nueva Ecija, Philippines. All ingredients (eggs, white sugar, active dry yeast, skimmed milk, lard, margarine, salt, and water) were mixed in a vat and kneaded until smooth. CCPL and PCPL were added in the mixture at different substitution levels: 0.5, 1, 2, 3 and 4% (w/w flour). Salt bread with no CPL was also prepared as control. The mixture was kneaded and cut into about 15-g portions which were rolled into salt bread crumbs and lined on cookie sheet. The samples were proofed for at least 3 h and then baked for 5 min at 200 – 250°F. The samples were cooled and packed in polyethylene bags and kept at ambient temperature until analyzed.

Screening of best formulation    The best formulation was determined using laboratory panel consisting of 14 staff from Philippine Rice Research Institute (PhilRice) as evaluators. Prior to the actual evaluation, product lexicon was developed, wherein sensory attributes for salt bread were identified and agreed upon by the same set of panelists (Meilgaard et al., 2007). Salt bread was randomly selected and coded with three-digit random numbers. One whole piece (60 – 64 mm width × 34 – 40 mm height) of coded salt bread of each treatment was presented to each sensory panelist one at a time. The attributes evaluated by the panelists were green color, aroma and taste (0=none; 15=very intense), surface texture appearance (0=smooth; 15=very rough), after-taste (0=none; 15=very perceptible), mouthfeel/texture (0=smooth; 15=very grainy), denseness (0=airy; 15=compact), moistness (0=compact; 15=very moist), tenderness (0=hard; 15=very tender), and overall acceptability (0= dislike; 15= like very much). The attributes of the samples were evaluated using a 15-cm unstructured scale. The panelists were then asked to rank the samples (1=highest). Samples with overall acceptability ratings of at least 7.5, the halfway point of the scale, were considered acceptable. The supplemented salt breads with the acceptability ratings not significantly different from the control for CCPL and PCPL were subjected to physical, microbial, and nutritional analyses, and consumer sensory evaluation.

Final product evaluation: Physical analysis    The moisture content (MC) of the samples was determined using AOAC Method 925.10(AOAC 2005). Water activity (a_w) was measured using a calibrated Lufft Durotherm a_w-Wert-Messer water activity meter.

Microbial load determination    Total plate and mold counts were determined by colony count methods of Vanderzant and Splittstoesser (1992).

Consumer acceptability test    Fifty nine PhilRice employees and on-the-job trainees (≥18 y/o) who are representative of adult Filipino consumers that regularly consume salt bread were recruited as consumer panelists. Respondents' profile of each panelist was asked such as name, gender, age, had previously participated in any taste tests of food products (yes/no), had consumed foods made from flour (yes/no), and had purchased or consumed supplemented salt bread (yes/no). The important qualities of supplemented bread were also determined by asking the panelists by ranking of qualities such as taste, odor/aroma, additional nutrients, appearance, packaging and other characteristics (1=most important quality). One whole piece of coded salt bread of each treatment was presented to each sensory panelist. Salt bread samples were presented to consumer panelists side-by-side. They were asked to rate the products based on their acceptability and preference. Consumer acceptance was determined using a 2-point hedonic scale (yes/no) and each product was given a rating (1=poor, 2=fair, 3=good, 4=very good, 5=excellent). Preference was determined by ranking of samples (1=highest), with no tied answers allowed. Purchase intent was determined by asking the respondents if they would be willing to purchase the products if these were available in the market and if they were aware that the samples have additional nutrients (question was answerable by yes/no). The frequency of positive responses was reported as percentage.

Nutritional analysis    Vitamin C, β-carotene, and folate were determined by high performance liquid chromatography (AOAC, 2005). Calcium and iron was determined by atomic absorption spectrophotometry (AOAC, 2005). Total dietary fiber was measured by enzymatic-gravimetric (AOAC, 2005), total sugars by Luff Schoorl titrimetry using the method of Egan et al. (1988), and total fat by acid hydrolysis (AOAC, 2005).

Statistical analysis    ANOVA was used to evaluate nutritional and sensory data, except for rank scores, which were assessed using Non-parametric Friedman Test (Lawless and Heymann, 1999). Subsequent comparison of means was done using Fisher's LSD (Meilgaard et al., 2007). Except for Friedman Test, data were analyzed using SAS statistical software v. 9.1 (SAS Institute, Cary, NC, USA). All tests were done in duplicates at p=0.05 level of significance.

Results and Discussion

Screening of best formulation Figure 1 shows the salt bread supplemented with different levels of CCPL and PCPL. Sensory evaluation showed that greenness, rough surface texture, leafy aroma and taste, and after-taste scores of the treatments generally increased as the percentage of CPL increased (Tables 1 and 2). All sensory attributes of salt breads with 0.5% CCPL or PCPL were not significantly different with those of the control, although up to 1% CCPL was deemed acceptable because its overall acceptability rating was higher than 7.5, the rating set as the minimum level of product acceptability. Addition of CPL either in crushed or powdered form did not affect the denseness, moistness and tenderness of salt bread. As observed in several other studies, incorporation of dehydrated green leafy vegetables at less than 5% does not affect the texture and quality of food products (Gupta and Prakash, 2011; Singh et al., 2007).

Fig. 1.

Salt bread supplemented with different levels of CPL (w/w rice flour)

Table 1. Laboratory sensory attributes of salt bread supplemented with CCPL

Sensory properties	Level of supplementation (% CCPL)
	0	0.5	1	2	3	4
Appearance
Color (green)1	0.09 ± 0.03e	0.66 ± 0.25e	1.86 ± 0.69d	2.81 ± 0.62c	4.33 ± 0.65b	5.39 ± 0.65a
Surface texture2	1.50 ± 0.58d	2.31 ± 1.23dc	2.89 ± 0.91c	4.19 ± 0.52b	4.89 ± 0.69ab	5.56 ± 0.67a
Aroma (leafy)1	0.00 ± 0.00e	0.33 ± 0.17e	2.41 ± 0.91d	4.79 ± 0.52c	7.15 ± 0.88b	8.82 ± 0.53a
Taste (leafy)1	0.00 ± 0.00e	0.17 ± 0.05e	3.11 ± 0.66d	4.41 ± 0.60c	7.18 ± 0.79b	8.49 ± 1.02a
After-taste3	0.11 ± 0.05d	1.11 ± 0.04d	1.95 ± 0.14c	3.91 ± 0.31b	5.67 ± 0.60a	6.35 ± 1.52a
Mouthfeel4	1.20 ± 0.16d	1.52 ± 0.26cd	1.79 ± 0.20bc	2.31 ± 0.34b	3.11 ± 0.68a	3.44 ± 0.91a
Denseness5	5.96 ± 1.82a	6.18 ± 1.85a	6.47 ± 1.88a	6.48 ± 1.21a	6.79 ± 1.26a	7.55 ± 1.27a
Moistness6	4.33 ± 0.87a	4.33 ± 0.69a	4.17 ± 0.91a	4.16 ± 0.51a	4.02 ± 0.88a	3.97 ± 0.46a
Tenderness7	9.38 ± 1.36a	9.30 ± 1.42a	8.98 ± 0.96a	8.82 ± 0.74a	8.38 ± 1.00a	8.62 ± 1.11a
Overall acceptability8	11.90 ± 1.23a	10.69 ± 1.18a	10.31 ± 1.14b	8.70 ± 1.17c	6.61 ± 0.92b	5.57 ± 1.04b

Mean values with the same letter in the same row are not significantly different at p=0.05.

¹  0=none; 15=very intense

²  0=smooth; 15=very rough

³  0=none; 15=very perceptible

⁴  0=smooth; 15=very grainy

⁵  0=airy; 15=compact

⁶  0=compact; 15=very moist

⁷  0=hard; 15=very tender

⁸  0=dislike; 15=like very much.

Table 2. Laboratory sensory attributes of salt bread supplemented with PCPL

Sensory properties	Level of supplementation (% PCPL)
	0	0.5	1	2	3	4
Appearance
Color (green)1	0.09 ± 0.00e	0.90 ± 0.38e	3.02 ± 0.66d	5.81 ± 0.84c	7.79 ± 0.98b	9.64 ± 1.10a
Surface texture2	1.05 ± 0.58d	2.0.1 ± 0.35d	3.14 ± 0.67c	4.01 ± 0.59b	4.58 ± 0.92ab	5.01 ± 0.79a
Aroma (leafy)1	0.00 ± 0.00e	0.51 ± 0.15e	2.44 ± 0.64d	4.99 ± 0.85c	6.89 ± 0.99b	8.17 ± 1.35a
Taste (leafy)1	0.00 ± 0.00e	0.25 ± 0.05e	2.92 ± 0.85d	5.35 ± 0.81c	6.89 ± 1.00b	8.33 ± 0.87a
After-taste3	0.11 ± 0.05e	0.59 ± 0.17e	2.11 ± 0.63d	3.99 ± 0.65c	5.51 ± 0.84b	6.45 ± 0.76a
Mouthfeel4	1.20 ± 0.16d	1.60 ± 0.46cd	1.93 ± 0.58bc	2.26 ± 0.67bc	2.61 ± 0.78ab	3.11 ± 0.92a
Denseness5	5.96 ± 1.82a	7.01 ± 1.97a	7.34 ± 1.94a	7.82 ± 1.95a	8.14 ± 2.42a	8.28 ± 2.47a
Moistness6	4.33 ± 0.87a	4.49 ± 0.94a	4.19 ± 0.93a	4.19 ± 0.84a	4.19 ± 0.52a	3.89 ± 0.95a
Tenderness7	9.38 ± 1.36a	9.15 ± 0.89a	9.04 ± 0.82a	8.87 ± 0.94a	8.78 ± 0.76a	8.73 ± 1.28a
Overall acceptability8	11.90 ± 1.23a	11.26 ± 0.98a	9.66 ± 1.03b	7.43 ± 1.24c	5.83 ± 0.99d	5.29 ± 0.96d

Mean values with the same letter in the same row are not significantly different at p = 0.05.

The samples were ranked according to overall quality. Significant differences were observed among samples, with Friedman statistic of 64.0 (χ²=11.07), but based on rank sum scores shown in Table 3, samples with 0.5% CCPL and PCPL were comparable with the unsupplemented salt bread. The differences of their rank sum scores with respect to the control were lower than 19.4, the Fisher's LSD. Hence, these samples were selected as final products and were subjected to consumer sensory evaluation and physicochemical and microbial analyses.

Table 3. Results of ranking sensory tests of different levels of supplementation of salt bread with crushed and powdered chili pepper leaves

Level of Supplementation (% CPL)	Rank Sums1
	CCPL salt bread	PCPL salt bread
0	17d	17d
0.5	29cd	28cd
1.0	38c	42c
2.0	58bc	54bc
3.0	71ab	70ab
4.0	81a	83a

¹  Values followed by the same letter within a column are not significantly different according to Fisher's LSD.

Consumer survey using 59 adult (≥18 yo) respondents consisted of 49% males and 51% females, with 41% belonging to the 25 – 34 y/o age bracket. Majority (78%) of the panelists had previously joined in taste tests of food products, 98% had consumed foods made from flour, and 95% had purchased or consumed supplemented bread. The important qualities of supplemented salt bread for most of the panelists were taste, followed by odor/aroma, additional nutrients, appearance, packaging, and other characteristics such as texture, brand, size and safety seal.

Different forms (crushed and powdered) of CPL were used in the study to assess if supplementation would yield visually appealing products. This is because appearance of a food product is a primary driver for consumer selection and purchase, and is therefore, a critical factor in its commercial success (Meilgaard et al., 2007). Salt bread with 0.5% CCPL obtained 97% acceptability from the consumer panelists (Table 4), while salt bread with 0.5% PCPL received a slightly lower acceptability score of 93%. Ninety percent of the respondents showed willingness to purchase CCPL salt bread if it was commercially available, while 86% would buy PCPL salt bread. However, when the respondents were informed that the products had additional nutrients, there were slight improvements in purchase intent ratings to 93% for CCPL and 95% for PCPL, generally reflecting consumer awareness and acceptance of products with health benefits. This verifies earlier reports that nutritional information of a product has a significant effect on the willingness of consumers to buy and use the product (Chen et al., 2010; iv). Rank sum scores showed similar preferences of consumers among the three products, with Friedman statistic of 2.8, lower than χ² (5.99) (Table 4). These findings indicate the potential marketability of salt bread supplemented with either CCPL or PCPL at 0.5% level.

Table 4. Preference scores and consumer acceptance of salt bread with CPL¹

Item	Salt bread Sample
	0%	0.5% PCPL	0.5% CCPL
1. % Acceptability2	97	93	97
2. Rating3	4	3	3
3. % Willingness to buy if 2
a. available in the market/store	93	86	90
b. with additional nutrients (iron, beta-carotene, dietary fiber)	92	95	93
4. Rank sum scores4	110	116	128

¹  Consumer sensory panelists aged ≥18 years old (n = 59).

²  Based on the percentage of positive responses; values with the same letter within a row are not significantly different at p = 0.05.

³  1 = poor, 2 = fair, 3 = good, 4 = very good, 5 = excellent.

⁴  Values indicate no significant differences according to non-parametric Friedman test.

Physicochemical and microbial properties    Moisture content of the samples were comparable (Table 5). Water activity values, which ranged from 0.82 to 0.83, did not differ significantly among samples. These values indicate safety of product for consumption based on the U.S. Food and Drug Administration (v) standard. The microbial growth (×10² CFU/g TPC and ×10¹ CFU/g mold) of the supplemented products was within permissible limits according to the standards of the United Nations World Food Program (vi).

Table 5. Moisture content, water activity values and microbial load of salt bread supplemented with CPL

Parameters	Salt Bread Sample
	0%	0.5% CCPL	0.5% PCPL
Moisture content (g/100 g)	20.07 ± 0.49a	19.53 ± 0.56a	19.82 ± 0.58a
Water activity	0.83 ± 0.01a	0.82 ± 0.00a	0.81 ± 0.01a
Total plate count (x102 CFU/g)	1.95	2.15	3.20
Mold count (CFU/g)	15.00	0.00	20.00

Data shown as mean ± standard deviation (n = 2).

Mean values with the same letter within a row are not significantly different at p = 0.05.

Nutritional Properties    Nutritional security can be cheaply achieved through the use of green leafy vegetables (Gupta et al., 2005; Afolayan and Jimoh, 2009). Among others, the nutrients that will significantly be contributed by the CPL are iron, β-carotene and folate. The importance of these micronutrients in humans cannot be overemphasized. Plant is the main dietary source of iron, vitamin A (in the form of β-carotene), and folate for many people in rural areas of developing countries.

Enriched bread samples were lower in total sugars, moisture and total fat content, but significantly higher in calcium, iron, β-carotene, folate and total dietary fiber levels than the control (Table 6). The incorporation of chili pepper leaves remarkably increased the β-carotene content from 0.0 to 214.5 µg/100 g and 237.5 µg/100 g in bread 0.5% CCPL and PCPL, respectively. In a study by Manaois et al. (2013), dried moringa leaves improved the beta-carotene content of rice crackers by eight times (19 to 152 µg/100 g) at a higher level of supplementation (2%), although processing of rice crackers requires higher temperature that could degrade beta-carotene. Dehydrated pumpkin, another vegetable well known for its high beta-carotene content, improved the carotenoid content of the product by only 5.5 times when used at 10% supplementation level in wheat bread (Rakcejeva et al., 2011).

Table 6. Nutritional composition of salt bread supplemented with CPL (per 100 g product)

Nutrients	Salt Bread Sample
	0%	0.5% CCPL	0.5% PCPL
Vitamin C (mg)	0.96 ± 0.05a	0.96 ± 0.03a	1.05 ± 0.07a
Calcium (mg)	10.80 ± 0.42b	11.55 ± 0.07b	12.80 ± 0.14a
Iron (mg)	3.65 ± 0.01c	4.28 ± 0.06a	3.98 ± 0.03b
Beta-carotene (µg)	0.00 ± 0.00c	214.50 ± 0.71b	237.50 ± 6.36a
Folate (µg)	273.50 ± 17.68b	401.00 ± 25.46a	418.50 ± 4.95a
Total Dietary Fiber (g)	1.68 ± 0.05b	2.42 ± 0.21a	1.94 ± 0.21ab
Total fat (g)	5.75 ± 0.04a	5.74 ± 0.04a	5.61 ± 0.04b

Data shown as mean ± standard deviation (n = 2).

Mean values with the same letter in the same row are not significantly different at p = 0.05.

The amount of folate almost doubled from 237.5 µg/100 g in the control sample to 418.5 µg/100 g in 0.5% PCPL (Table 6). Like many green leafy vegetables, chili pepper leaves are significant source of naturally occurring folate that incorporating them in the salt bread enhanced the nutrient content of the product.

The iron level of the salt bread significantly increased by the addition of 0.5% CCPL (4.28 mg) and 0.5% PCPL (3.98 mg) (Table 6). These values and observations are similar to that reported by Singh et al. (2007) in products with green leafy vegetables, where improvement in the nutritional quality of conventional foods (green gram dal and paratha) was noted with the incorporation of dehydrated bathua leaves.

Philippine data from the latest national nutrition survey revealed that, only 26.1% and 12.4% of Filipino adults met the recommended (27 mg iron and 600 µg folate per day for pregnant and lactating women) intake for iron and folate, respectively, and that more than 70% of the population lack iron in their diet (FNRI, 2008). There was also an observed decreasing trend for iron and vitamin A intakes from 1993 to 2008 among children and women. Based on the results from this study, a serving (40 g or 3 pieces) of bread with 0.5% chili pepper leaves, crushed or powdered, can supply additional 4% (15.8 µg) of the daily requirement of a Filipino adult for vitamin A, 9.5% (1.7 mg) iron, and 4% (167.4 µg) folate for a 2000-calorie diet. In CCPL bread, the dietary fiber content also slightly improved from 1.68 g/100 g to 2.42 g/100 g.

Results indicated the potential of CPL as an inexpensive source of micronutrients for certain at-risk groups of the population and the use of salt bread as a good vehicle for supplementation. With the high beta-carotene, iron, and folate levels in chili-supplemented bread, children and pregnant women might benefit from eating the product to prevent deficiencies which may lead to blindness, anemia, and birth defects, among others.

Conclusion

Results of this study clearly showed that the leaves of chili pepper can significantly provide additional micronutrients when incorporated in salt bread as a means to improve iron, folate, and vitamin A nutrition in areas where iron deficiency anemia, vitamin A and folate deficiencies are prevalent. Use of CPL can be recommended to improve the micronutrient intake of the population. Utilization of CPL in other food products is therefore worth exploring.

Acknowledgement    The authors thank Mrs. Necitas Malabanan and staff of KN Bakery & General Merchandise for the salt bread formulation and use of their facilities. Appreciation is also extended to Mr. Ramon Garcia for the chili pepper leaves.

References

•  Afolayan,  A.J. and  Jimoh,  O.F. (2009). Nutritional quality of some wild leafy vegetables in South Africa. Int. J. Food Sci. Nutr., 60, 424-4531.
• Association of Official Analytical Chemists (AOAC) (2005). Official Methods of Analysis, 18th ed., Washington DC, USA: Method no. 922.06, 925.10, 985.35, 985.29.
•  Chen,  S. H.,  Chen,  H. F., and  Wang,  H. C. (2010). Do health claims matter for consumer preference on tea beverage? Experimental evidence from Taiwan. Paper presented at the 115th Joint EAAE/AAEA Seminar, Freising-Weihenstephan, Germany, September 15–17, 2010, p. 15.
•  deMan,  J.M. (1999). “Principles of Food Chemistry”. 3rd Ed., Aspen Publishers, Gaithersburg, MD, USA, pp. 21-23.
•  deVogel,  S.,  Dindore,  V.,  van Engeland,  M.,  Goldbohm,  R.A.,  van den Brandt,  P.A., and  Weijenberg,  M.P. (2008). Dietary folate, methionine, riboflavin, and vitamin B6 and risk of sporadic colorectal cancer. J. Nutr., 138, 2372-2378.
•  Egan,  H.,  Kirk,  R.S., and  Sawyer,  R. (1988). “Pearson's Chemical Analysis of Foods”. 8th Ed., Longman Group Ltd., United Kingdom. pp. 152-153.
• Food and Nutrition Research Institute (FNRI) (2013). 8th National Nutrition Survey. Department of Science and Technology, Manila, Philippines.
• Food and Nutrition Research Institute (FNRI) (2008). 7th National Nutrition Survey. Department of Science and Technology, Manila, Philippines.
• Food and Nutrition Research Institute (FNRI) (1997). “The Philippine Food Composition Tables”. Department of Science and Technology, Manila, Philippines, p. 4, 41.
•  Fujimori,  S.,  Gudis,  K.,  Takahashi,  Y.,  Kotoyori,  M.,  Tatsuguchi,  A.,  Ohaki,  Y., and  Sakamoto,  C. (2011). Determination of the minimal essential serum folate concentration for reduced risk of colorectal adenoma. Clin. Nutr., 30, 653-658.
•  Gupta,  S. and  Prakash,  J. (2011). Nutritional and sensory quality of micronutrient-rich traditional products incorporated with green leafy vegetables. Int. Food Res. J., 18, 667-675.
•  Gupta,  S.,  Jyothi Lakshmi,  A.,  Manjunath,  M.N., and  Prakash,  J. (2005). Analysis of nutrient and antinutrient content of underutilized green leafy vegetables. Food Sci. Technol., 38, 339-345
•  Lawless,  H.T. and  Heymann,  H. (1999). “Sensory Evaluation of Food Principles and Practice”. Aspen Publishers, New York, NY, USA, pp. 694-696.
•  Manaois,  R.V.,  Morales,  A.V., and  Abilgos-Ramos,  R.G. (2013). Acceptability, shelf life and nutritional quality of moringa-supplemented rice crackers. Philipp. J. Crop Sci., 38, 1-8.
•  Meilgaard,  M.C.,  Civille,  G.V., and  Carr,  B.T. (2007). “Sensory Evaluation Techniques”. 4th Ed., CRC Press, Taylor & Francis Group, USA.
•  Ng,  X.N.,  Chye,  F.Y., and  Mohd Ismail,  A. (2012). Nutritional profile and antioxidative properties of selected tropical wild vegetables. Int. Food Res. J., 19, 1487-1496.
•  Rakcejeva,  T.,  Galoburda,  R.,  Cude,  L., and  Strautniece,  E. (2011). Use of dried pumpkins in wheat bread production. Procedia Food Sci., 1, 441-447.
•  Singh,  L.,  Ydav,  N.,  Kumar,  A.R.,  Gupta,  A.K.,  Chacko,  J.,  Parvin,  K., and  Tripathi,  U. (2007). Preparation of value added products from dehydrated bathua leaves (Chenopodium album Linn.). Indian J. Nat. Prod. Resour, 6, 6-10.
•  Vanderzant,  C. and  Splittstoesser,  D.F. (1992), “Compendium of Methods for the Microbiological Examination of Foods”. American Public Health Association, Washington D.C., USA.
•  Yaldiz,  G.,  Ozguven  M., and  Sekeroglu,  N. (2010). Variation in capsaicin contents of different Capsicum species and lines by varying drying parameters. Ind.Crops. Prod., 32, 434-438.
• i) http://www.mb.com.ph/articles/244314/dost-lauds-maker-veggie-noodles/ (July 26, 2010)
• ii) http://punto.com.ph/news/printpage/7219/ (July 26, 2010)
• iii) http://pia-ilocos.com/index.php?option=comcontent&mtask=view&id=2882&Itemid=2/ (July 26, 2010)
• iv) http://etd.lsu.edu/docs/available/etd-07072004-130134/unrestricted/Bond-thesis.pdf/ (February 11, 2013)
• v) http://www.fda.gov/Food/ScienceResearch/ResearchAreas/SafePracticesforFoodProcesses/ucm094145.htm/ (February 15, 2013)
• vi) http://foodquality.wfp.org/FoodSafetyandHygiene/TestingCommodities/MicrobiologicalTests/tabid/316/Default.aspx?PageContentID=395/ (January 12, 2012)