Nutritious Novel Snacks from Cereals, Legumes, and Skimmed Milk Powder
1. Introduction
The global snack industry has witnessed exponential growth over the past decades, driven by urbanization, lifestyle changes, and consumer demand for convenient foods. However, conventional snacks are often criticized for their high fat, sugar, and salt content, coupled with low nutritional value. This has created a pressing need for healthier alternatives that combine taste, convenience, and nutritional benefits.
Extrusion technology has emerged as a powerful tool in developing such products. By blending cereals, legumes, and dairy proteins, researchers aim to create snacks that are not only palatable but also rich in protein, essential amino acids, and minerals. This approach addresses nutritional deficiencies common in cereal-based diets, particularly in developing countries.
2. Importance of Developing Nutritious Snacks
- Public Health: Rising rates of obesity, diabetes, and cardiovascular diseases highlight the need for healthier snack options.
- Protein-Energy Malnutrition: In many regions, cereal-based diets lack sufficient protein quality. Legumes and dairy supplementation can bridge this gap.
- Consumer Trends: Modern consumers increasingly seek functional foods that provide health benefits beyond basic nutrition.
- Food Security: Utilizing locally available cereals and legumes supports sustainable food systems and reduces reliance on imported ingredients.
3. Raw Materials and Formulation
The study formulated six snack samples: one control (100% corn) and five experimental blends combining cereals (corn, wheat, rice), legumes (chickpeas, faba beans), and skimmed milk powder. The goal was to enhance protein content, amino acid balance, and mineral density while maintaining desirable sensory properties.
| Formula | Corn (%) | Wheat (%) | Rice (%) | Chickpea (%) | Faba Bean (%) | Skimmed Milk (%) |
|---|---|---|---|---|---|---|
| Control | 100 | – | – | – | – | – |
| F1 | 50 | 15 | – | 25 | – | 10 |
| F2 | 50 | 15 | – | – | 25 | 10 |
| F3 | 50 | – | 15 | 25 | – | 10 |
| F4 | 50 | – | 15 | – | 25 | 10 |
| F5 | 50 | 7.5 | 7.5 | 12.5 | 12.5 | 10 |
These formulations were carefully designed to balance macronutrients and improve the amino acid profile. The inclusion of skimmed milk powder provided high-quality animal protein, while legumes contributed lysine, an essential amino acid often deficient in cereals.
4. Processing Method: Extrusion Cooking
Extrusion cooking is a high-temperature, short-time (HTST) process widely used in the food industry to produce ready-to-eat snacks. It involves forcing a moistened, starchy mixture through a barrel under controlled temperature and pressure, followed by sudden release through a die. This process induces starch gelatinization, protein denaturation, enzyme inactivation, and microbial destruction, resulting in safe, shelf-stable, and texturally appealing products.
4.1 Advantages of Extrusion
- Improved Digestibility: Starch gelatinization and protein unfolding enhance nutrient bioavailability.
- Versatility: Allows incorporation of diverse raw materials (cereals, legumes, dairy proteins).
- Energy Efficiency: HTST minimizes nutrient losses compared to conventional cooking.
- Texture Development: Expansion during extrusion creates light, crispy structures.
4.2 Extrusion Parameters
The study optimized extrusion conditions to balance expansion, texture, and nutrient retention. Key parameters included:
| Parameter | Range Applied | Impact on Product |
|---|---|---|
| Moisture Content | 14–16% | Controls expansion and texture |
| Barrel Temperature | 120–150°C | Ensures starch gelatinization and microbial safety |
| Screw Speed | 250–300 rpm | Affects shear, mixing, and expansion ratio |
| Die Diameter | 3–5 mm | Determines final shape and porosity |
5. Physicochemical Properties of Extruded Snacks
The physical and chemical properties of the extruded snacks were significantly influenced by the formulation and processing conditions. These properties determine consumer acceptance and nutritional quality.
5.1 Bulk Density and Expansion Ratio
- Bulk Density: Decreased with higher legume and milk powder inclusion, producing lighter snacks.
- Expansion Ratio: Improved in mixed formulations compared to control, enhancing crispiness.
5.2 Water Absorption and Solubility Index
Extrusion increased the water absorption index (WAI), indicating improved starch gelatinization. The water solubility index (WSI) also rose, reflecting partial starch degradation and improved digestibility.
5.3 Color Characteristics
Color analysis showed slight reductions in lightness (L*) and increases in redness (a*) in legume-enriched snacks. These changes were acceptable to consumers and did not negatively affect sensory appeal.
5.4 Texture Profile
Texture analysis revealed that snacks with balanced cereal-legume blends had optimal hardness and crispness. Excessive legume addition slightly reduced expansion but improved protein density.
6. Chemical Composition and Nutritional Value
The nutritional composition of the extruded snacks was significantly improved by incorporating legumes and skimmed milk powder. Compared to the control (100% corn), the experimental formulations showed higher protein, balanced amino acid profiles, and enriched mineral content. These improvements make the snacks suitable for addressing protein-energy malnutrition and micronutrient deficiencies.
6.1 Proximate Composition
The proximate analysis revealed notable differences between the control and experimental snacks:
| Component | Control (%) | Experimental Range (%) | Nutritional Impact |
|---|---|---|---|
| Protein | 6.9 | 12.7 – 15.5 | Enhanced protein density |
| Fat | 2.8 | 3.1 – 3.8 | Slight increase, still low-fat |
| Carbohydrates | 77.2 | 68.5 – 72.4 | Reduced, balanced with protein |
| Ash (minerals) | 1.1 | 2.3 – 3.0 | Higher mineral density |
| Energy (kcal/100g) | 345 | 372 – 381 | More energy-dense |
6.2 Amino Acid Profile
The inclusion of legumes and skimmed milk powder significantly improved the amino acid balance. Cereals are typically deficient in lysine, while legumes complement this deficiency. Skimmed milk powder provided additional essential amino acids such as methionine and tryptophan.
| Amino Acid | Control (g/100g protein) | Experimental Range | FAO/WHO Requirement |
|---|---|---|---|
| Lysine | 2.1 | 4.5 – 5.2 | 4.5 |
| Methionine + Cystine | 2.0 | 2.8 – 3.1 | 2.5 |
| Threonine | 2.5 | 3.2 – 3.6 | 3.0 |
| Tryptophan | 0.6 | 1.0 – 1.2 | 1.0 |
6.3 Mineral Content
Mineral analysis showed that experimental snacks were significantly richer in calcium, potassium, magnesium, and zinc compared to the control. This is attributed to the contribution of legumes and skimmed milk powder.
| Mineral | Control (mg/100g) | Experimental Range (mg/100g) | Nutritional Benefit |
|---|---|---|---|
| Calcium | 22 | 65 – 92 | Bone health, growth |
| Potassium | 180 | 310 – 420 | Electrolyte balance |
| Magnesium | 28 | 55 – 72 | Metabolism, nerve function |
| Zinc | 1.1 | 2.4 – 3.0 | Immunity, growth |
7. Protein Digestibility and Biological Value
One of the most critical aspects of evaluating protein-rich snacks is their digestibility and biological value. While cereals provide energy, their proteins are often limited in essential amino acids and exhibit lower digestibility. By incorporating legumes and skimmed milk powder, the study significantly improved both the digestibility and the biological value of the extruded snacks.
7.1 In Vitro Protein Digestibility (IVPD)
Protein digestibility was measured using enzymatic hydrolysis methods. Results indicated that experimental formulations had markedly higher digestibility compared to the control.
| Formula | IVPD (%) | Improvement vs. Control |
|---|---|---|
| Control (100% corn) | 77.8 | – |
| F1 | 86.5 | +11.2% |
| F2 | 87.1 | +11.9% |
| F3 | 88.6 | +13.9% |
| F4 | 89.3 | +14.8% |
| F5 | 88.1 | +13.2% |
7.2 Protein Efficiency Ratio (PER)
The Protein Efficiency Ratio (PER) is an indicator of protein quality based on growth performance in animal models. The experimental snacks showed PER values ranging from 2.1 to 2.4, compared to 1.8 in the control. This demonstrates that the protein blends were more effective in supporting growth and development.
7.3 Biological Value (BV)
Biological Value measures the proportion of absorbed protein that is retained in the body for maintenance and growth. The inclusion of skimmed milk powder significantly boosted BV, making the snacks comparable to high-quality protein sources.
| Formula | Biological Value (BV) | Interpretation |
|---|---|---|
| Control | 65 | Low quality protein |
| F1–F5 | 78 – 85 | High quality protein, suitable for growth |
7.4 Net Protein Utilization (NPU)
Net Protein Utilization combines digestibility and biological value to reflect the overall efficiency of protein use in the body. Experimental snacks achieved NPU values of 70–75, compared to 58 in the control, confirming their superior nutritional quality.
7.5 Implications
- Enhanced protein digestibility ensures better nutrient absorption, especially important for children and adolescents.
- High biological value makes these snacks suitable for populations at risk of malnutrition.
- Balanced amino acid profiles reduce the risk of deficiencies common in cereal-based diets.
8. Sensory Properties and Consumer Acceptability
Beyond nutritional improvements, the success of any novel snack depends on its sensory qualities—appearance, texture, flavor, and overall acceptability. A sensory evaluation was conducted with a trained panel of 35 individuals to assess the consumer perception of the extruded snacks. The results confirmed that the incorporation of legumes and skimmed milk powder did not compromise sensory appeal; in fact, several formulations were rated higher than the control.
8.1 Sensory Evaluation Parameters
Panelists evaluated the snacks using a 9-point hedonic scale, where 1 = "dislike extremely" and 9 = "like extremely." The following attributes were assessed:
- Appearance (color, shape, uniformity)
- Texture (crispness, hardness, mouthfeel)
- Flavor (taste, aroma, aftertaste)
- Overall acceptability
8.2 Sensory Scores
| Formula | Appearance | Texture | Flavor | Overall Acceptability |
|---|---|---|---|---|
| Control | 7.2 | 7.0 | 7.1 | 7.0 |
| F1 | 7.5 | 7.6 | 7.8 | 7.7 |
| F2 | 7.6 | 7.8 | 7.9 | 7.9 |
| F3 | 8.0 | 8.2 | 8.3 | 8.2 |
| F4 | 7.8 | 8.0 | 8.1 | 8.0 |
| F5 | 8.1 | 8.3 | 8.4 | 8.3 |
8.3 Key Findings
- Appearance: All experimental snacks maintained attractive color and shape, with slight darkening due to legumes.
- Texture: Crispness improved in F3 and F5, which were rated highest for mouthfeel.
- Flavor: Legume and milk powder addition enhanced flavor complexity, producing a nutty, savory taste.
- Overall Acceptability: F3 and F5 were rated “excellent,” surpassing the control in consumer preference.
8.4 Implications for Marketability
The sensory evaluation confirmed that nutritional enrichment did not compromise consumer appeal. On the contrary, the enhanced flavor and texture of the experimental formulations suggest strong potential for market success. These snacks can be positioned as both healthy and enjoyable, appealing to health-conscious consumers and children alike.
9. Storage Stability and Shelf Life
One of the most important aspects of developing novel snacks is ensuring their stability during storage. Consumers expect snacks to maintain freshness, flavor, and safety over extended periods. The study evaluated the storage stability of the extruded snacks over six months at ambient conditions, focusing on chemical, physical, and sensory changes.
9.1 Peroxide Value (PV)
Peroxide value is a key indicator of lipid oxidation, which leads to rancidity. All experimental formulations maintained low PV levels throughout storage, indicating strong oxidative stability.
| Formula | Initial PV (meq/kg) | PV after 6 months | Interpretation |
|---|---|---|---|
| Control | 0.9 | 3.8 | Acceptable, slight oxidation |
| F1 | 0.8 | 2.9 | Stable |
| F2 | 0.7 | 2.6 | Highly stable |
| F3 | 0.8 | 3.0 | Stable |
| F4 | 0.7 | 2.5 | Highly stable |
| F5 | 0.8 | 2.8 | Stable |
9.2 Moisture Content
Moisture content remained within safe limits (<10%) across all formulations, preventing microbial growth and maintaining crispness. Legume-enriched snacks showed slightly lower moisture uptake due to higher protein and fiber content.
9.3 Sensory Stability
Sensory evaluation during storage revealed that flavor, texture, and overall acceptability were well preserved. F2 and F4 maintained the highest scores after six months, indicating superior stability.
9.4 Packaging Considerations
- Snacks were stored in laminated, airtight pouches to minimize oxygen and moisture exposure.
- Proper packaging extended shelf life by reducing lipid oxidation and staling.
- Future improvements could include nitrogen flushing or vacuum packaging for even longer stability.
9.5 Conclusion on Shelf Life
The study confirmed that the experimental snacks remained safe, nutritious, and organoleptically acceptable for at least six months under ambient storage. This makes them commercially viable for large-scale production and distribution.
10. Comparison with Conventional Market Snacks
To evaluate the true potential of the developed extruded snacks, it is essential to compare them with conventional market snacks such as potato chips, corn puffs, and fried extrudates. The comparison highlights the nutritional superiority and health benefits of the experimental formulations.
10.1 Nutritional Comparison
Market snacks are often energy-dense but nutrient-poor, whereas the experimental snacks provide balanced macronutrients and essential micronutrients.
| Parameter | Conventional Snacks | Experimental Snacks | Health Implication |
|---|---|---|---|
| Protein (%) | 4 – 6 | 12 – 15 | Supports growth and repair |
| Fat (%) | 20 – 35 | 3 – 4 | Lower risk of obesity and CVD |
| Energy (kcal/100g) | 480 – 520 | 372 – 381 | Balanced energy intake |
| Minerals | Low | High (Ca, Mg, Zn, K) | Improved micronutrient intake |
| Digestibility | Moderate | High (85–89%) | Better nutrient absorption |
10.2 Sensory Comparison
- Texture: Conventional fried snacks are crunchy but oily; experimental snacks are crisp and light without excess oil.
- Flavor: Market snacks rely heavily on artificial flavors and salt; experimental snacks offer natural, nutty, and savory notes.
- Appearance: Both categories are visually appealing, but experimental snacks have a slightly darker hue due to legumes.
10.3 Health and Market Implications
The comparison clearly demonstrates that the experimental snacks are nutritionally superior and healthier than conventional options. With rising consumer awareness about diet-related diseases, these snacks can be positioned as functional foods that combine health benefits with enjoyable sensory qualities. They also align with global trends toward plant-based, protein-rich, and low-fat snack alternatives.
11. Industrial and Commercial Applications
The successful development of nutritious extruded snacks from cereals, legumes, and skimmed milk powder opens up significant opportunities for the food industry. These products can be positioned not only as healthier alternatives to conventional snacks but also as functional foods with added value for specific consumer groups.
11.1 Industrial Advantages
- Scalability: Extrusion technology is already widely used in the snack industry, making large-scale production feasible without major infrastructure changes.
- Cost-Effectiveness: Using locally available cereals and legumes reduces production costs and reliance on imported raw materials.
- Versatility: Formulations can be easily adjusted to create different flavors, shapes, and textures, catering to diverse consumer preferences.
- Extended Shelf Life: Six-month stability ensures suitability for mass distribution and export markets.
11.2 Target Consumer Segments
The enriched snacks can be marketed to a wide range of consumer groups:
| Consumer Group | Nutritional Benefit | Market Potential |
|---|---|---|
| Children & Adolescents | High protein, calcium, and energy for growth | School snacks, fortified products |
| Health-Conscious Adults | Low fat, high protein, functional nutrition | Fitness and wellness markets |
| Elderly Population | Easily digestible protein, minerals for bone health | Senior nutrition programs |
| Low-Income Communities | Affordable source of protein and micronutrients | Food aid and social programs |
11.3 Commercial Opportunities
- Functional Snacks: Marketed as protein-rich, mineral-fortified alternatives to conventional chips and puffs.
- Private Label Products: Retailers can adopt formulations under their own brands.
- Export Potential: Long shelf life and nutritional appeal make them suitable for international markets.
- Customization: Flavors (cheese, herbs, spices) can be tailored to regional preferences.
11.4 Challenges and Considerations
- Consumer education is needed to highlight the nutritional benefits compared to traditional snacks.
- Pricing strategies must balance affordability with profitability.
- Regulatory approvals for health claims (e.g., “high protein,” “rich in calcium”) must be secured.
- Marketing campaigns should emphasize both taste and health benefits to attract mainstream consumers.
11.5 Future Prospects
With increasing global demand for healthier, sustainable, and functional foods, these extruded snacks have strong potential to become a mainstream product category. They align with trends such as plant-based nutrition, protein fortification, and reduced-fat snacking, making them highly competitive in the evolving food market.
12. Conclusion and Future Outlook
The development of nutritious extruded snacks from cereals, legumes, and skimmed milk powder represents a significant advancement in the field of functional foods. By combining the complementary nutritional properties of these ingredients, researchers successfully created products that are rich in protein, balanced in essential amino acids, fortified with minerals, and highly digestible. Importantly, these improvements were achieved without compromising sensory qualities such as taste, texture, and appearance.
12.1 Key Achievements
- Protein content increased by more than double compared to conventional corn-based snacks.
- Essential amino acid balance was optimized, meeting or exceeding FAO/WHO recommendations.
- Digestibility and biological value were significantly enhanced, ensuring efficient nutrient utilization.
- Mineral content (Ca, Mg, Zn, K) was enriched, addressing common micronutrient deficiencies.
- Sensory evaluation confirmed high consumer acceptability, with several formulations outperforming the control.
- Storage stability of at least six months was demonstrated, ensuring commercial viability.
12.2 Broader Implications
These findings have important implications for public health, food security, and the global snack industry. The products can serve as affordable, nutritious alternatives in regions where protein-energy malnutrition is prevalent. They also align with consumer trends toward healthier, plant-based, and functional foods, making them attractive in both developing and developed markets.
12.3 Future Research Directions
- Flavor Innovation: Exploring natural herbs, spices, and flavorings to further enhance sensory appeal.
- Fortification: Incorporating vitamins (A, D, B-complex) and omega-3 fatty acids for added functionality.
- Sustainability: Using underutilized local crops to reduce environmental impact and support biodiversity.
- Clinical Trials: Assessing the impact of these snacks on growth, immunity, and overall health in target populations.
- Market Expansion: Developing product lines tailored for children, athletes, and elderly consumers.
12.4 Final Thoughts
The study demonstrates that it is possible to create snacks that are not only enjoyable but also nutritionally superior. By leveraging extrusion technology and strategic ingredient combinations, the food industry can address pressing nutritional challenges while meeting consumer demand for healthier products. These snacks represent a promising step toward a future where convenience and health go hand in hand.
Source: ScienceDirect – Nutritious novel snacks from some of cereals, legumes and skimmed milk powder
13. Final Summary
This comprehensive review of nutritious extruded snacks formulated from cereals, legumes, and skimmed milk powder demonstrates the potential of food innovation to address both consumer demand and public health needs. By strategically combining plant and dairy proteins, the study achieved significant improvements in protein content, amino acid balance, mineral density, digestibility, and sensory quality.
Compared to conventional market snacks, these products are lower in fat, richer in protein, and fortified with essential micronutrients, making them ideal for children, adolescents, health-conscious adults, and vulnerable populations. Their six-month shelf life and strong consumer acceptability further confirm their commercial viability.
Ultimately, these snacks represent a new generation of functional foods that combine convenience, taste, and health benefits. They align with global trends toward sustainable, plant-based, and fortified foods, offering a promising solution for the future of healthy snacking.
Source: ScienceDirect – Nutritious novel snacks from some of cereals, legumes and skimmed milk powder
