Spoilage of cereals grains and legumes

By

Assoc.Prof.Dr.Narumol Matan

Cereal grains, legumes and tuber crop

• Cereal grains

– Rice, Corn, Wheat, Rye, Barley

Legumes

– Black beans, Red beans, Green beans, Soy beans Tuber crop

– Cassava, Yam, Wild yam, Taro

2. Chemical composition and properties of rice

Husk

Rice bran

Aleurone layer

Germ

Endosperm

Chemical composition of Wheat

1. Carbohydrate

• 2. Protein – Endosperm proteins : Gliadin, Glutenin

– Embryo proteins : Leuosin, Globulin

– Bransproteins : Prolamin, Globulin, Albumin

• 3. Lipid – Free lipid

– Bound lipids

• 4. Minerals and vitamins – Minerals are most common in bran.

– The most common vitamin is B complex vitamins.

Characteristics of legumes

Chemical composition of legumes

Kind Calories Proteins Fats Minerals Carbohydrates

Soy bean 335 38 18 4.7 31.1

Peanut 343 25.6 43.4 2.5 23.4

Green bean 340 23.9 1.3 0.4 60.4

Characteristics of cassava

Trunk

Rhizome swollen knot at root base

Tuber

Chemical composition of cassava roots • Composition in cassava in 100 grams

– Water 60.21-75.32

– Peel 4.08-14.08

– Flour 25.87-41.88

– Cyanide 2.85-39.27

• Composition in flour

– Starch 71.9-85.0

– Protein 1.57-5.78

– Fiber 1.77-3.95

– Ash 1.20-2.80

– Fat 0.06-0.43

Toxins found in tapioca • 1. Cyanogenic glucoside are 2 types ; linamarin and

lotaustralin

• 2. Disposal – 2.1 Boil at temperature over 150 °C

– 2.2 Grind and place to break the enzyme

– 2.3 Microorganism

linamarin & lotaustralin Hydrogen cyanide or prussic acid

linamarase

Removal of Toxin from Cassava

Natural microflora • It is usually contaminated by bacteria, yeasts and molds

during planting, harvesting, storage and processing.

• Common fungus; such as Alternaria, Fusarium, Helminthosporium, Cladosporium, Aspergillus, Penicillium

• External influences such as air humidity and temperature are important factors for natural microflora growth.

• The internal influence is aw

Contamination of food Material Processing Products

Aflatoxins in legumes • Aflatoxins are one of the most commonly found toxins in food.

Aflatoxin is a toxin that is caused by microorganisms such as Aspergillus flavus, A. parasiticus and A. nomius

• Aflatoxin is a good heat-resistant and resistant to 260 ° C. Therefore, cooking under 100 ° C can not destroy this poison. For this reason, we can find aflatoxins in food products, peanuts or corn.

What is Aflatoxins?

• The substance is produced directly from microorganisms, especially Aspergillus flavus and Aspergillus parasiticus

• There are several types of aflatoxins such as Aflatoxins B1,B2,G1 and G2

• Aflatoxin B1 is the most toxic substance, causes of Liver Cancer

• Causes of Aflatoxin Summarized as follows

1. Drought in the 30 days before harvest

2. Pods are destroyed by diseases and insects in the soil.

3. Calcium deficiency causes disease from pod fungus.

4. Harvest when the beans overgrown

5. Take a long time to reduce the moisture at a safe point or raining while it is drying.

Toxicity of -toxin • The poisoning can occur suddenly and causes liver cancer.

Consuming food containing this toxins 2-6 mg per day will cause acute poisoning.

• In children, high fever, seizures, vomiting and death in 72 hours.

• But if the toxins in small amounts will accumulate in the body, causing cancer in the liver.

How to control the contamination of fungus and aflatoxin • Selection of areas where Aspergillus flavus was not reported.

• Tillage

• Selection of suitable planting dates to avoid rain during harvest and drying.

• Drying of peanuts and keeping them in dry and cool conditions.

• Pods or rotten seeds to bury or burn. It may contain contaminated aflatoxins.

Spoilage of beverages

• There are several types of beverages. Degradation of beverage products depends on the type of beverage.

1. Ropiness is a condition in which the liquid become characteristically viscous and pours as an “oily” stream. It is caused by Acetobacter, Lactobacillus, Pediococcus cerevisiae and Gluconobacter oxydans

Spoilage of beverages

2. Sarcinae sickness is caused by P. cerevisiae, which produces a honeylike odor. This odor is the result of diacetyl production by the spoilage organism in combination with the normal odor of beer.

3. Sourness in beers is caused by Acetobacter spp. These organisms are capable of oxidizing ethanol to acetic acid, and the sourness that results is referable to increased levels of acetic acid.

4. Turbidity and off-odors are caused by Zymomonas anaerobia and Saccharomyces spp. Growth of bacteria is possible in beers because of a normal pH range of 4-5 and a good content of utilizable nutrients.

Cause of other infections

• Megasphaera cerevisiae acetic acid, propionic acid

• Selenomonas lacticifex lactate

• Pectinatus cerevisiphilus turbid , Off-flavor

Spoilage of wine

• Candida valida being the most important yeast. Growth of this organism occurs at the surface of wines, where a thin film is formed. The organisms attack alcohol and other constituents from this layer and create an appearance that is sometime referred to as wine flowers

• Acetobacter oxidize alcohol acetic acid Acetic acid or tourne disease • Malo-lactic; Malic is organic acid in grape must and wine, and in the

malo-lactic fermentation, contaminating bacteria degrade malic acid to lactic acid and CO2 :

- Leuconostoc oenos, Pediococci, Lactobacilli • Lactobacillus plantarum could produce lactic acid:

L(-)-Malic acid L(+)-Lactic acid + CO2 Malo-lactic enzyme

Tartaric acid Lactic acid acetic acid CO2