Unit 3: Plants and Plant Products of Industrial Value
Table of Contents
Vegetable Oils and Fats
Oils and fats are major reserve food materials in plants, primarily found in seeds and fruits.
Edible Oil-Yielding Plants
These oils are used primarily for cooking and human consumption.
- Groundnut (Arachis hypogaea):
- Morphology: Herbaceous annual; fruit is an indehiscent legume produced underground (geocarpy).
- Extraction: Crushing the seeds (kernels).
- Uses: Cooking oil, margarine, and health implications include high protein content but also potential allergens.
- Coconut (Cocos nucifera): Yields oil from the dried endosperm (copra).
- Soybean (Glycine max): High in polyunsaturated fats; extracted from seeds.
- Mustard (Brassica spp.): Extracted from seeds; widely used in Indian cooking.
Non-Edible Oil-Yielding Plants
These are used for industrial purposes like soap making, lubricants, or biofuels.
| Plant | Family | Common Uses |
|---|---|---|
| Karanja (Pongamia pinnata) | Fabaceae | Biodiesel, medicinal purposes. |
| Mahua (Madhuca longifolia) | Sapotaceae | Soap making, skin care. |
| Castor (Ricinus communis) | Euphorbiaceae | Lubricants, laxatives. |
Sugar and Starches
Sugarcane (Saccharum officinarum)
- Morphology: A tall perennial grass with thick, segmented stalks.
- Processing: Extraction of juice by crushing, followed by clarification, evaporation, and crystallization.
- By-products:
- Molasses: Used for alcohol production.
- Bagasse: Fiber residue used for paper and fuel.
- Press mud: Used as fertilizer.
Potato (Solanum tuberosum)
- Morphology: Underground modified stem known as a tuber.
- Propagation: Vegetatively via "eyes" or tuber pieces.
- Post-harvest: Requires cold storage to prevent sprouting and starch degradation.
Fibres
Fibres are elongated, thick-walled cells that provide structural support to plants.
Classification Based on Origin
- Surface Fibres: Found on the surfaces of seeds or fruits (e.g., Cotton, Coir).
- Soft/Bast Fibres: Found in the phloem of stems (e.g., Jute).
- Hard/Leaf Fibres: Found in the vascular bundles of leaves (e.g., Sisal).
Specific Fibre Crops
- Cotton (Gossypium spp.): Seed surface hair; extracted by ginning.
- Jute (Corchorus spp.): Bast fibre from the stem; extracted by retting (soaking in water to rot off soft tissues).
- Coir (Cocos nucifera): Extracted from the fibrous husk (mesocarp) of the coconut.
Rubbers
Rubber is a secondary metabolite (latex) produced by specialized cells called laticifers.
Natural/Para Rubber (Hevea brasiliensis)
- Tapping: The process of making a controlled incision in the bark to collect latex.
- Processing: Latex is coagulated using acids (like acetic acid), pressed into sheets, and smoked or air-dried.
- Uses: Tires, footwear, surgical gloves, and industrial belts.
Exam Tips
- Fibre Extraction: The term "Retting" is almost always asked in short notes regarding Jute.
- Sugar Industry: Focus on the by-products (Bagasse, Molasses) as they have high industrial significance.
- Rubber: Be clear about the "Tapping" procedure; mention that the incision must reach the laticifers without damaging the cambium.
Common Mistakes
- Confusing **Groundnut** (seed oil) with **Castor** (non-edible oil) in terms of usage.
- Describing the Potato as a root; it is a modified **stem** (tuber).