Part I Raw materials
Part I Raw materials
Raw material selection- fruits and Ⅴ egetables L. Bedford, Campden and Chorleywood Food Research Association 1.1 Introduction Fresh fruits and vegetables are utilised in a wide range of chilled products. They may be sold whole, or peeled (for example peeled potatoes and onions)or further prepared(e.g. carrot batons). After washing or further preparation they form ingredients for mixes such as mixed fruit or salad packs or for further processing in a wide range of products. From this it can be seen that raw material requirements can be very varied but are specific to each end use. Sourcing of suitable raw material is essential for the production of final products of consistently high quality and for this both the producer and the user need to have a clear understanding of the requirements In this chapter some of the criteria for selection will be discussed. The examples are drawn from a range of fruit and vegetable crops. Most whole fruits and vegetables are best stored at chill temperatures and thus come naturally under the scope of this book. Some however, such as potatoes and tomatoes and some other fruits are low-temperature sensitive and should ideally be kept at higher temperatures. However even these items, once they are cut and prepared need to be kept chilled, to avoid enzyme-mediated changes and disease-related spoilage, both of which proceed more rapidly at higher temperatures Supply of suitable raw material requires collaboration between the grower and the purchaser of the produce. In effect, the grower forms the first link in the food chain. The decisions made, including variety selection and agronomic practices and the grower's skill in harvesting and where appropriate in storing the crop are crucial steps in the supply of high-quality raw material for chilled fruit and vegetable products
1.1 Introduction Fresh fruits and vegetables are utilised in a wide range of chilled products. They may be sold whole, or peeled (for example peeled potatoes and onions) or further prepared (e.g. carrot batons). After washing or further preparation they form ingredients for mixes such as mixed fruit or salad packs or for further processing in a wide range of products. From this it can be seen that raw material requirements can be very varied but are specific to each end use. Sourcing of suitable raw material is essential for the production of final products of consistently high quality and for this both the producer and the user need to have a clear understanding of the requirements. In this chapter some of the criteria for selection will be discussed. The examples are drawn from a range of fruit and vegetable crops. Most whole fruits and vegetables are best stored at chill temperatures and thus come naturally under the scope of this book. Some however, such as potatoes and tomatoes and some other fruits are low-temperature sensitive and should ideally be kept at higher temperatures. However even these items, once they are cut and prepared need to be kept chilled, to avoid enzyme-mediated changes and disease-related spoilage, both of which proceed more rapidly at higher temperatures. Supply of suitable raw material requires collaboration between the grower and the purchaser of the produce. In effect, the grower forms the first link in the food chain. The decisions made, including variety selection and agronomic practices and the grower’s skill in harvesting and where appropriate in storing the crop are crucial steps in the supply of high-quality raw material for chilled fruit and vegetable products. 1 Raw material selection – fruits and vegetables L. Bedford, Campden and Chorleywood Food Research Association
0 Chilled foods 1.2 Criteria for selection First of all it is necessary to consider the factors which contribute to product variability and what makes raw material suitable for different purposes, particularly for use in chilled food products. Some of the factors are genetically ontrolled. Thus varieties may differ in size, shape and other characteristics Many plant characteristics are also influenced by environmental factors, such as site and climate and seasonal weather patterns. These genetic and environmental aspects interact, contributing to the variability of the produce at harvest The parts of the plant which are consumed may be leaves, stems, roots flowering heads, fruits or seeds, all requiring harvesting at the correct stage of maturity. Further factors apply after harvest, such as the handling and storage of he products before they are sold or prepared for further processing. Post-harvest factors can have a considerable impact on shelf-life and quality 1. 2.1 Variety Plant species have recognisable inherited characteristics, which can be used to distinguish them from other species. Members of a species are generally able to interbreed easily, but much less easily, or not at all with other species. within a species, natural variation gives rise to groups of individuals with small but definite differences. which are known as 'varieties. when the variations are brought about by human intervention as in plant breeding then botanists use the term cultivars. However in common parlance the term ' is used for the an-made products of plant breeding as well When selecting raw material for particular purposes, one of the important criteria under human control, is the choice of suitable varieties. Th are many different ways in which varieties can differ. There may be obvious differences in colour, shape and size. may be differences in field characteristics, such as yield, plant growth habit and disease resistance. In some cases flavour and other sensory characteristics may differ For most crops, a range of varieties can be used for any specific purpose, for example, a number of different varieties of Dutch white cabbage all possess the ick leaf texture and white colour required by the chilled salad producer. In other cases, the choice of a variety suitable for a specific purpose may be more limited; for instance an apple variety such as Cox may be specifically selected for a chilled fruit salad. because of its skin colour. which will enhance the overall appearance. A good variety has to meet the requirements of the primary producer, processor, retailer and ultimately the consumer Agronomic characteristics Traditionally, farmers and growers have selected varieties for their field or agronomic performance. They have been concerned to achieve high yields, this being a major factor affecting profitability. This may be in terms of total yield or, more importantly, of marketable yield. The latter refers to the saleable
1.2 Criteria for selection First of all it is necessary to consider the factors which contribute to product variability and what makes raw material suitable for different purposes, particularly for use in chilled food products. Some of the factors are genetically controlled. Thus varieties may differ in size, shape and other characteristics. Many plant characteristics are also influenced by environmental factors, such as site and climate and seasonal weather patterns. These genetic and environmental aspects interact, contributing to the variability of the produce at harvest. The parts of the plant which are consumed may be leaves, stems, roots, flowering heads, fruits or seeds, all requiring harvesting at the correct stage of maturity. Further factors apply after harvest, such as the handling and storage of the products before they are sold or prepared for further processing. Post-harvest factors can have a considerable impact on shelf-life and quality. 1.2.1 Variety Plant species have recognisable inherited characteristics, which can be used to distinguish them from other species. Members of a species are generally able to interbreed easily, but much less easily, or not at all with other species. Within a species, natural variation gives rise to groups of individuals with small but definite differences, which are known as ‘varieties’. When the variations are brought about by human intervention as in plant breeding then botanists use the term ‘cultivars’. However in common parlance the term ‘variety’ is used for the man-made products of plant breeding as well. When selecting raw material for particular purposes, one of the most important criteria under human control, is the choice of suitable varieties. There are many different ways in which varieties can differ. There may be obvious differences in colour, shape and size. There may be differences in field characteristics, such as yield, plant growth habit and disease resistance. In some cases flavour and other sensory characteristics may differ. For most crops, a range of varieties can be used for any specific purpose, for example, a number of different varieties of Dutch white cabbage all possess the thick leaf texture and white colour required by the chilled salad producer. In other cases, the choice of a variety suitable for a specific purpose may be more limited; for instance an apple variety such as Cox may be specifically selected for a chilled fruit salad, because of its skin colour, which will enhance the overall appearance. A good variety has to meet the requirements of the primary producer, processor, retailer and ultimately the consumer. Agronomic characteristics Traditionally, farmers and growers have selected varieties for their field or ‘agronomic’ performance. They have been concerned to achieve high yields, this being a major factor affecting profitability. This may be in terms of total yield or, more importantly, of marketable yield. The latter refers to the saleable 20 Chilled foods
Raw material selection -fruits and vegetables 21 produce after all waste and defective material has been removed. Taking a root crop, such as carrots, all the roots will be lifted from the soil and grading will emove undersized and misshapen roots Disease resistance is another major issue. Field diseases can cause complete rop losses, or they may produce blemishes, which cause produce to be downgraded. Chemical pesticides can be applied to control some, but not all diseases. Genetic resistance is preferable, reducing the need for chemicals Disease resistance may be controlled by a single gene or by several genes acting together(multigene resistance). Single gene resistance is easier to work with However the disadvantage is that plant pathogens often rapidly produce new races able to overcome this type of resistance. An example is found in downy mildew of spinach( Peronospora farinosa f sp spinaciae ). The disease is difficult to control chemically and varieties have been bred with specific genes for resistance, originally to races 1, 2 and 3 of the disease. Following the appearance in 1995 of the new race 4, whole crops were wiped out. Plant breeders have now produced a series of new varieties with resistance to race 4 but the resistance of these varieties may also have a limited life. Multigene resistance (field tolerance) gives greater stability. Some varieties of lettuce show this type of resistance to lettuce downy mildew(Bremia lactucae) Plant habit is another varietal characteristic, which is particularly important when the flowering parts of the plant or the seeds are consumed. Plants should have sturdy stems to enable them to remain erect in windy conditions or when the foliage is wet. Varieties are said to have ' good standing abilityand not to lodge' or become flattened. In the green bean crop, plant breeders have given considerable thought to the plant architecture. Stems need to be sufficiently strong to support the combined of pods produced and, as yields increase this becomes more of a problem. If all the pods were to be bunched together at the tops of the plants this might make for easier harvesting, but it could cause increased lodging. Plants on which the pods are distributed more evenly throughout the plant canopy are more likely to remain upright A major change in varieties over the last fifty years is associated with partial complete mechanisation of harvesting. Older varieties of many crops, such as cauliflower and lettuce would have individual plants producing their heads over a period of time. In crops such as peas and beans individual pods were also produced over a long period. With the introduction of machine harvesting, the objective was once-over harvesting and the result, over years of breeding, has been varieties where individual heads mature very evenly. Peas and beans are said to be more 'determinate', that is to say that after producing a certain number of flowering nodes growth tends to stop. The pods then all develop and can be harvested at one time While all these field characteristics are necessary for the growth of crops, successful marketing of the crop requires attention to characteristics required by of the fina,or, the retailer and ultimately by the consumer. These relate to quality roduct
produce after all waste and defective material has been removed. Taking a root crop, such as carrots, all the roots will be lifted from the soil and grading will remove undersized and misshapen roots. Disease resistance is another major issue. Field diseases can cause complete crop losses, or they may produce blemishes, which cause produce to be downgraded. Chemical pesticides can be applied to control some, but not all diseases. Genetic resistance is preferable, reducing the need for chemicals. Disease resistance may be controlled by a single gene or by several genes acting together (multigene resistance). Single gene resistance is easier to work with. However the disadvantage is that plant pathogens often rapidly produce new races able to overcome this type of resistance. An example is found in downy mildew of spinach (Peronospora farinosa f sp spinaciae). The disease is difficult to control chemically and varieties have been bred with specific genes for resistance, originally to races 1, 2 and 3 of the disease. Following the appearance in 1995 of the new race 4, whole crops were wiped out. Plant breeders have now produced a series of new varieties with resistance to race 41 but the resistance of these varieties may also have a limited life. Multigene resistance (field tolerance) gives greater stability. Some varieties of lettuce show this type of resistance to lettuce downy mildew (Bremia lactucae). Plant habit is another varietal characteristic, which is particularly important when the flowering parts of the plant or the seeds are consumed. Plants should have sturdy stems to enable them to remain erect in windy conditions or when the foliage is wet. Varieties are said to have ‘good standing ability’ and not to ‘lodge’ or become flattened. In the green bean crop, plant breeders have given considerable thought to the plant architecture. Stems need to be sufficiently strong to support the combined weight of pods produced and, as yields increase, this becomes more of a problem. If all the pods were to be bunched together at the tops of the plants this might make for easier harvesting, but it could cause increased lodging. Plants on which the pods are distributed more evenly throughout the plant canopy are more likely to remain upright. A major change in varieties over the last fifty years is associated with partial or complete mechanisation of harvesting. Older varieties of many crops, such as cauliflower and lettuce would have individual plants producing their heads over a period of time. In crops such as peas and beans individual pods were also produced over a long period. With the introduction of machine harvesting, the objective was once-over harvesting and the result, over years of breeding, has been varieties where individual heads mature very evenly. Peas and beans are said to be more ‘determinate’, that is to say that after producing a certain number of flowering nodes growth tends to stop. The pods then all develop and can be harvested at one time. While all these field characteristics are necessary for the growth of crops, successful marketing of the crop requires attention to characteristics required by the processor, the retailer and ultimately by the consumer. These relate to quality of the final product. Raw material selection – fruits and vegetables 21
Chilled foods Shape and size Within some crops there is a range of shapes and sizes. For instance there is a range of types of carrots with different shapes and size of roots. Nantes varieties have cylindrical roots and so are preferred for pre-packing. Berlicum varieties are also cylindrical. They are generally larger and mature later in the season than Nantes varieties. The other common UK types are the conical Chantenays and Autumn King varieties which have very large roots tapering to a point. Larger roots of cylindrical or slightly conical varieties are suitable for slicing in chilled food products A recent development has been the breeding of specific varieties for ' mini vegetableproduction. The concept is a response to consumer perception that small size equates to high quality and is seen as a way of adding value to vegetable products such as cauliflower. The varieties may also require special growing techniques. Varieties may also be selected according to their ability to produce the correct size of portion for prepared foods. Cauliflowers are often presented ready cut into florets and varieties differ in the ease with which they can be cut up and the size of florets produced. For chopping or dicing, large size consideration. Large cabbages are specified for processing uses sucsant is required and the overall yield of prepared product is an import coleslaw production, the total yield of cabbage shreds being the major concern This contrasts with retail sale where smaller varieties are required Colour and appearance It is often said that the consumer buys by eye, so an attractive colour and appearance is essential. Varieties often vary in colour. The characteristic colours of different apple varieties make them easily identified. They differ not only in the ground colour( Coxes are yellow and red, Bramleys are green) but also in the markings known as russetting. Chilled food manufacturers will consider the flesh colour, as well as the skins and the ability to resist grey discoloration when selecting a variety to provide colour to a mixed fruit salad Modern commercial carrot varieties are orange, but they were arrived at by careful selection from a varied ancestral gene pool in which yellow and purple colours were common. More recently a series of large-rooted varieties were developed for dicing. They had a deeper orange colour that was particularly evenly spread across the core and flesh of the roots. Colour may not be so important where the product is chopped or otherwise prepared. White cabbage for retail sale needs to have bright colour and fresh appearance. Slight greyness may be acceptable if the cabbage is used for coleslaw, as the colour will be masked by the mayonnaise To the consumer, of course, the ultimate requirement is good eating quality, and food products should have good natural flavour and texture. Varieties of some crops such as apples have very distinctive flavours and consumers commonly select their own favourites e.g. Cox, Golden Delicious, Russet. In other crops
Shape and size Within some crops there is a range of shapes and sizes. For instance there is a range of types of carrots with different shapes and size of roots. Nantes varieties have cylindrical roots and so are preferred for pre-packing. Berlicum varieties are also cylindrical. They are generally larger and mature later in the season than Nantes varieties. The other common UK types are the conical Chantenays and Autumn King varieties which have very large roots tapering to a point. Larger roots of cylindrical or slightly conical varieties are suitable for slicing in chilled food products. A recent development has been the breeding of specific varieties for ‘mini vegetable’ production. The concept is a response to consumer perception that small size equates to high quality and is seen as a way of adding value to vegetable products such as cauliflower. The varieties may also require special growing techniques. Varieties may also be selected according to their ability to produce the correct size of portion for prepared foods. Cauliflowers are often presented ready cut into florets and varieties differ in the ease with which they can be cut up and the size of florets produced.2 For chopping or dicing, large size is required and the overall yield of prepared product is an important consideration. Large cabbages are specified for processing uses such as coleslaw production, the total yield of cabbage shreds being the major concern. This contrasts with retail sale where smaller varieties are required. Colour and appearance It is often said that the consumer buys by eye, so an attractive colour and appearance is essential. Varieties often vary in colour. The characteristic colours of different apple varieties make them easily identified. They differ not only in the ground colour (Coxes are yellow and red, Bramleys are green) but also in the markings known as ‘russetting’. Chilled food manufacturers will consider the flesh colour, as well as the skins and the ability to resist grey discoloration when selecting a variety to provide colour to a mixed fruit salad. Modern commercial carrot varieties are orange, but they were arrived at by careful selection from a varied ancestral gene pool in which yellow and purple colours were common. More recently a series of large-rooted varieties were developed for dicing. They had a deeper orange colour that was particularly evenly spread across the core and flesh of the roots. Colour may not be so important where the product is chopped or otherwise prepared. White cabbage for retail sale needs to have bright colour and fresh appearance. Slight greyness may be acceptable if the cabbage is used for coleslaw, as the colour will be masked by the mayonnaise. Flavour and texture To the consumer, of course, the ultimate requirement is good eating quality, and food products should have good natural flavour and texture. Varieties of some crops such as apples have very distinctive flavours and consumers commonly select their own favourites e.g. Cox, Golden Delicious, Russet. In other crops, 22 Chilled foods