Fruit Juices and Syrups

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Questions and Answers

What type of fruit juice is pineapple juice?

Clear fruit juice

Cloudy fruit juice (correct)

Fruit syrup

Concentrated fruit juice

What is the total soluble solid of squash?

50%

60%

40% (correct)

30%

What is the purpose of concentrated fruit juices?

For further blending or processing (correct)

For direct consumption

For preservation purpose (correct)

For exporting to other countries

What is cordial?

Clear fruit juice Signup and view all the answers

What is nectar?

Diluted fruit juice with additives Signup and view all the answers

What is the advantage of non-heat concentrated fruit juices?

High quality Signup and view all the answers

What affects the quality of raw materials in fruit juice production?

All of the above Signup and view all the answers

What is the purpose of heat concentration of fruit juices?

For preservation purpose Signup and view all the answers

What is the purpose of adding hydrolytic enzymes in clear fruit juice treatment?

To increase pressing efficiency Signup and view all the answers

Which of the following is NOT a method of clarification of juice?

Heat treatment Signup and view all the answers

What is the purpose of heat treatment in fruit juice treatment?

To inactivate enzymes Signup and view all the answers

What is the purpose of centrifugal separation in fruit juice treatment?

To clarify the juice Signup and view all the answers

What is the purpose of stabilization of fruit juice?

To precipitate protein residues Signup and view all the answers

What is the purpose of blending in fruit juice treatment?

To add flavorings and colorants Signup and view all the answers

What is the difference between pure juice and nectar?

Pure juice is pasteurized before canning, while nectar is not Signup and view all the answers

What is the purpose of CO2 aeration in fruit juice stabilization?

To remove oxygen from the juice Signup and view all the answers

What is the primary purpose of sorting in fruit juice processing?

All of the above Signup and view all the answers

What is the recommended level of total chlorine in water for washing fresh fruits and vegetables?

50-150 ppm Signup and view all the answers

Which step is responsible for inactivating enzymes in fruit juice processing?

Blanching Signup and view all the answers

What is the purpose of blanching in fruit juice processing?

To inactivate enzymes Signup and view all the answers

Which step follows pressing in clear fruit juice processing?

Clarification Signup and view all the answers

What is the purpose of crushing and shredding in fruit juice processing?

To extract juice from fruits Signup and view all the answers

What is the purpose of homogenization in fruit juice processing?

To stabilize fruit juice Signup and view all the answers

Which step is responsible for separating the juice from the pulp in fruit juice processing?

Pressing Signup and view all the answers

What is the purpose of homogenization in fruit juice production?

To keep the juice away from separation Signup and view all the answers

What is the range of particle size after homogenization?

167-560µm Signup and view all the answers

What is the purpose of oxygen elimination in fruit juice production?

To reduce discoloration and vitamin C loss Signup and view all the answers

What is the typical homogenization pressure?

120-150 atm Signup and view all the answers

What is the purpose of gelling agents in fruit juice production?

To help reduce separation in juice Signup and view all the answers

What is the TSS of fruit syrup?

65% Signup and view all the answers

What is the portion of fruit pulp in squash?

25% Signup and view all the answers

What is the TSS of cordial?

30% Signup and view all the answers

What is the purpose of shredding or crushing tough and crunchy fruits?

To reduce the size of the matter for pressing Signup and view all the answers

Why is heat treatment required for soft fruits?

To soften the fruits for crushing Signup and view all the answers

What is the purpose of oxygen elimination during fruit crushing?

To prevent oxidation and spoilage Signup and view all the answers

What is the purpose of inactivating oxidation enzymes during fruit crushing?

To prevent oxidation and spoilage of the fruit Signup and view all the answers

What is the purpose of destemming before juice extraction in bunched fruits?

To remove stems and leave only the fruit Signup and view all the answers

What is the purpose of soaking or steaming dried fruits before juice extraction?

To rehydrate the fruits and make them suitable for juice extraction Signup and view all the answers

What is the purpose of pressing in fruit juice extraction?

To extract the juice from the fruit Signup and view all the answers

What is the benefit of oxygen elimination during fruit crushing?

Improves product quality and ensures uniformity of box volume Signup and view all the answers

Study Notes

Classification of Fruit Juices

Cloudy fruit juices: orange juice, pineapple juice
Clear fruit juices: grape juice, apple juice

Fruit Syrup

Concentrated fruit juices with Total Soluble Solids (TSS) up to 60%
Used for further blending or processing

Squash

Fruit juice with 25% fruit pulp addition
TSS of 40%
Requires dilution before use

Cordial

Clear fruit juice (e.g., lemon juice)

Nectar

Diluted fruit juice with water, sugar, organic acids, and additives

Concentrated Fruit Juices

Used for preservation purposes
Used as materials for other food and drink productions (e.g., nectar, jam, jelly)
Economic benefits: heat concentration is low-cost but low-quality, while non-heat concentration is high-cost but high-quality

Fruit Juice Production

Factors affecting quality of raw materials:
- Variety
- Cultivation
- Maturity/ripening
- Harvesting conditions

Treatments for Fruit Juices

Heat treatment: inactivates enzymes
Addition of hydrolytic enzymes: increases pressing efficiency, reduces pressing time, and improves juice clarity

Clarification of Juice

Enzymatic methods:
- Pectolytic enzymes (e.g., pectinase, decomposing, hydrolytic)
- Starch liquefying enzymes
Clarifying agents:
- Physical precipitation (e.g., kaolin, bentonite)
- Chemical precipitation (e.g., gelatin, albumin, casein)

Stabilization of Fruit Juice

Heating: precipitates protein residues before bottling
CO2 aeration
Blending: pure juice is pasteurized before canning, while nectar has to pass through blending step

Fruit Juice Processing Flow

Cloudy fruit juice:
- Raw material sorting
- Washing
- Blanching
- Blending
- Crushing
- Shredding
- Homogenization
- Oxygen elimination
- Pasteurization
- Bottling
Clear fruit juice:
- Raw material sorting
- Washing
- Oxygen elimination
- Blending
- Filtration
- Pasteurization
- Packaging

Raw Material Reception

Requirements:
- Fresh, no physical damage/defect, no disease, right maturity/ripening level
- Appropriate transportation method
- Separated zone for raw material reception
- Weight load and quality check before handling
- Pre-treatment before handling (if necessary)

Washing and Sorting

Washing:
- Clean/chlorinated water
- Theoretically, 2-7 ppm of free chlorine and pH 6.0-7.5 in washing water is sufficient to kill bacteria
- Recommended: 50-150 ppm of total chlorine in water for start washing fresh fruits and vegetables
Sorting:
- To eliminate unripe or over-ripe fruits
- To eliminate damaged or infected fruits
- To eliminate strange materials (e.g., stones)
- Sizing the fruits

Homogenization

Process of mixing pulp and juice into a homogeneous state
Purpose: keep the juice away from separation
Gelling agents (e.g., pectin, CMC) can help reduce separation in juice
Particle size: 167-560µm
Used high pressure to force the product through a very small gap (0.1 mm)
Homogenization pressure: 120-150 atm

Oxygen Elimination

Reduces contact between oxygen and enzymes in juice
Reduces discoloration of the juice, vitamin C loss, and can swelling
O2 accelerates metal corrosion by oxidizing the protective layer, leading to taste and color changes

Juice Extraction

Methods depend on structure and composition of fruits
For tough and crunchy fruits: shredding/crushing is required before pressing
Size of the shredded/crushed matter cannot be too big or small
Seed and peel have to be eliminated sometimes

Fruit Juice Extraction

Bunched fruits: need destemming before juice extraction
Soft fruits: heat treatment required before crushing
Dried fruits: soaking/steaming before juice extraction

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Description

This quiz covers different types of fruit juices, including cloudy and clear juices, fruit syrups, and squashes, along with their characteristics and uses.