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冷冻食品保质期试验.pdf
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Shelf Life Testing:
\.g w5I&Uz%T0Procedures and Prediction Methods for Frozen食品伙伴个性空间#~+_ x6E.P`({8O
Foods
|8z7DN}(`0Bin Fu
PWQ| On|y od u0Kellogg's Battle Creek MI食品伙伴个性空间 nC R9DP`
Theodore P. Labuza食品伙伴个性空间4DS3Us*A[
Dept. of Food Science & Nutrition, University of Minnesota食品伙伴个性空间1~4S;x,w o"[)i
1334 Eckles Ave., St. Paul, MN 55108
{;?#a6GI%|C(T02
i6yd0oi"e?019.1 Introduction
lHXm.IM^y/R0The shelf life of a food can be defined as the time period within which the food is safe
4N(n+H2@ w L0to consume and/or has an acceptable quality to consumers. Just like any other food,
H.L.L J0u7ti0frozen foods deteriorate during storage by different modes or mechanisms, as食品伙伴个性空间'vta$vsM O0~bA
summarized in Table 1. Microbes usually are not a problem since they cannot grow at食品伙伴个性空间 _UX!k$@
freezing temperatures unless subjected to extensive temperature abuse above the
!Vjo"]C1Q&pn6@0freezing point. Enzymes are a big concern for frozen foods, which can cause flavor
qQW;E5u|Gf0change (lipoxygenase) in non-blanched fruits and vegetables and accelerated
N]!lt1M4j0deterioration reactions in meat and poultry (enzymes released from disrupted
0X*c B,N&{-f0membranes during precooking). Cell damage or protein and starch interactions during
2k#K4x&T6|p0freezing cause drip and mushiness upon thawing. Discoloration could occur by nonenzymatic食品伙伴个性空间9U0l@"}.G\+lh7M
browning, bleaching, and freezer burn. Vitamin C loss is often a major食品伙伴个性空间"g([,v*P~.G
concern for frozen vegetables. Physical changes, such as package ice formation,食品伙伴个性空间:G5r_x`+DL
moisture loss, emulsion destabilization, recrystallization of sugars and ice of frozen
?']bI?f0desserts are often accelerated by fluctuating temperatures.
wd_V)\7I*D!c o&e0For any specific frozen product, which mode determines its shelf life, depends
j[D$t\CMmo0on the product characteristics (raw materials, ingredients, formulation), pre-freezing食品伙伴个性空间8w5{-E,d7t/]6j.QG
treatment, freezing process, packaging film and processes, and of course storage食品伙伴个性空间.^{%E%yM c#\
conditions. All of the quality deterioration and potential hazards are usually
1@$S;_e'AV`Gt0exaggerated or complicated by a fluctuating time-temperature environment (e.g.食品伙伴个性空间 voS*y5I7g@%D{@
freeze/thaw cycle) during storage. On the other hand, the shelf life of a frozen food
G#e i(OOVx/x0can be extended through ingredient selection, process modification and change of食品伙伴个性空间_H4_;Ga%R5z
package or storage conditions, as discussed in Section 3 of this book.食品伙伴个性空间x ghO#ga i;v
This chapter will focus on shelf life testing of frozen foods for product食品伙伴个性空间kL:X9| m:lD
development and market practices. Shelf life testing consists basically of selecting the食品伙伴个性空间)t7E'G4ud EH
quality characteristics which deteriorate most rapidly in time and the mathematical
!D3xs MSt.\'uS;}2j0modeling of the change. Table 19.1 can be used as a reference for the selection of
&R3LQl r fN `0quality characteristics, which depends on the specific product and usually requires
$dKd0C6G0professional judgment. Mathematical modeling of quality deterioration will be
8@0Sj!X a(]\p0discussed next.食品伙伴个性空间`"Py Df&v
3食品伙伴个性空间]r|9P-Xvq&UD
Table 19.1 Deterioration modes of frozen foods食品伙伴个性空间I:pdn1~Z
Frozen Foods Deterioration Modes
K9luK L$|0Frozen meats, poultry and seafood Rancidity食品伙伴个性空间}bVKW:~V%r8K(e,f
Toughening (protein denaturation)
Q)^:MM8J vG.V5Uv0Discoloration食品伙伴个性空间jn%M{qc#Q v|t
Desiccation (freezer burn)食品伙伴个性空间7Mv ](V P;Tc o
Frozen fruits and vegetables Loss of nutrients (vitamins)
.b6~D&P.I'w)dr0Loss of texture (temperature abuse)
BU D lv.Zgs0Loss of flavor (lipoxygenase, peroxidase)食品伙伴个性空间bJ-qRA
Loss of tissue moisture (forming package ice)
F wD%X,[+P,J%p0Discoloration
V7w8kZ'^-^T(x0Frozen concentrated juices Loss of nutrients (vitamins)食品伙伴个性空间-h @2`2c6dM2B
Loss of flavor食品伙伴个性空间P1jTN x6M
Loss of cloudiness食品伙伴个性空间1o0nVS? CGUz1b
Discoloration食品伙伴个性空间&Y8N}9U"Q+xa
Yeast growth (upon temperature abuse)食品伙伴个性空间^R'kb.b_fi
Frozen dairy products
s[2\2O0e:E0(ice cream, yogurt, etc.)
,hZrO${G6UV K0Iciness (recrystallization of ice crystals)食品伙伴个性空间w9be*_#V
Sandiness (lactose crystallization)食品伙伴个性空间n{%o0L~
Loss of flavor食品伙伴个性空间4TrqDP_a"B
Disruption of emulsion system
@+m}"@Qx:X2uD0Frozen convenience foods Rancidity in meat portions食品伙伴个性空间IC3n3mV
Weeping and curdling of sauces
,Xcp~#N1q0Loss of flavor食品伙伴个性空间SG@d|l8T#B
Discoloration食品伙伴个性空间hAZlR)qO
Package ice
yOX1P/E9`$EH(z$K0Frozen bakery products (raw dough,
5itAxqnC0bread, croissants)食品伙伴个性空间+ma ^hqE
Burst can (upon temperature abuse) (dough)食品伙伴个性空间i#O V}0ja K ?
Loss of fermentation capability (dough)
QLro%O7Dr0k0Staling (becoming leathery)
4ocr3ArC0Loss of fresh aroma
PYgppK^z019.2 Modeling of quality deterioration
)C;C|,j _019.2.1 Basic equation
&@/~6D[%w0A frozen food starts to degrade once it is produced (Figure 19.1). The rate and食品伙伴个性空间0I2w6n1d |
the degree of degradation depends on both the composition and the environmental食品伙伴个性空间&F
\.g w5I&Uz%T0Procedures and Prediction Methods for Frozen食品伙伴个性空间#~+_ x6E.P`({8O
Foods
|8z7DN}(`0Bin Fu
PWQ| On|y od u0Kellogg's Battle Creek MI食品伙伴个性空间 nC R9DP`
Theodore P. Labuza食品伙伴个性空间4DS3Us*A[
Dept. of Food Science & Nutrition, University of Minnesota食品伙伴个性空间1~4S;x,w o"[)i
1334 Eckles Ave., St. Paul, MN 55108
{;?#a6GI%|C(T02
i6yd0oi"e?019.1 Introduction
lHXm.IM^y/R0The shelf life of a food can be defined as the time period within which the food is safe
4N(n+H2@ w L0to consume and/or has an acceptable quality to consumers. Just like any other food,
H.L.L J0u7ti0frozen foods deteriorate during storage by different modes or mechanisms, as食品伙伴个性空间'vta$vsM O0~bA
summarized in Table 1. Microbes usually are not a problem since they cannot grow at食品伙伴个性空间 _UX!k$@
freezing temperatures unless subjected to extensive temperature abuse above the
!Vjo"]C1Q&pn6@0freezing point. Enzymes are a big concern for frozen foods, which can cause flavor
qQW;E5u|Gf0change (lipoxygenase) in non-blanched fruits and vegetables and accelerated
N]!lt1M4j0deterioration reactions in meat and poultry (enzymes released from disrupted
0X*c B,N&{-f0membranes during precooking). Cell damage or protein and starch interactions during
2k#K4x&T6|p0freezing cause drip and mushiness upon thawing. Discoloration could occur by nonenzymatic食品伙伴个性空间9U0l@"}.G\+lh7M
browning, bleaching, and freezer burn. Vitamin C loss is often a major食品伙伴个性空间"g([,v*P~.G
concern for frozen vegetables. Physical changes, such as package ice formation,食品伙伴个性空间:G5r_x`+DL
moisture loss, emulsion destabilization, recrystallization of sugars and ice of frozen
?']bI?f0desserts are often accelerated by fluctuating temperatures.
wd_V)\7I*D!c o&e0For any specific frozen product, which mode determines its shelf life, depends
j[D$t\CMmo0on the product characteristics (raw materials, ingredients, formulation), pre-freezing食品伙伴个性空间8w5{-E,d7t/]6j.QG
treatment, freezing process, packaging film and processes, and of course storage食品伙伴个性空间.^{%E%yM c#\
conditions. All of the quality deterioration and potential hazards are usually
1@$S;_e'AV`Gt0exaggerated or complicated by a fluctuating time-temperature environment (e.g.食品伙伴个性空间 voS*y5I7g@%D{@
freeze/thaw cycle) during storage. On the other hand, the shelf life of a frozen food
G#e i(OOVx/x0can be extended through ingredient selection, process modification and change of食品伙伴个性空间_H4_;Ga%R5z
package or storage conditions, as discussed in Section 3 of this book.食品伙伴个性空间x ghO#ga i;v
This chapter will focus on shelf life testing of frozen foods for product食品伙伴个性空间kL:X9| m:lD
development and market practices. Shelf life testing consists basically of selecting the食品伙伴个性空间)t7E'G4ud EH
quality characteristics which deteriorate most rapidly in time and the mathematical
!D3xs MSt.\'uS;}2j0modeling of the change. Table 19.1 can be used as a reference for the selection of
&R3LQl r fN `0quality characteristics, which depends on the specific product and usually requires
$dKd0C6G0professional judgment. Mathematical modeling of quality deterioration will be
8@0Sj!X a(]\p0discussed next.食品伙伴个性空间`"Py Df&v
3食品伙伴个性空间]r|9P-Xvq&UD
Table 19.1 Deterioration modes of frozen foods食品伙伴个性空间I:pdn1~Z
Frozen Foods Deterioration Modes
K9luK L$|0Frozen meats, poultry and seafood Rancidity食品伙伴个性空间}bVKW:~V%r8K(e,f
Toughening (protein denaturation)
Q)^:MM8J vG.V5Uv0Discoloration食品伙伴个性空间jn%M{qc#Q v|t
Desiccation (freezer burn)食品伙伴个性空间7Mv ](V P;Tc o
Frozen fruits and vegetables Loss of nutrients (vitamins)
.b6~D&P.I'w)dr0Loss of texture (temperature abuse)
BU D lv.Zgs0Loss of flavor (lipoxygenase, peroxidase)食品伙伴个性空间bJ-qRA
Loss of tissue moisture (forming package ice)
F wD%X,[+P,J%p0Discoloration
V7w8kZ'^-^T(x0Frozen concentrated juices Loss of nutrients (vitamins)食品伙伴个性空间-h @2`2c6dM2B
Loss of flavor食品伙伴个性空间P1jTN x6M
Loss of cloudiness食品伙伴个性空间1o0nVS? CGUz1b
Discoloration食品伙伴个性空间&Y8N}9U"Q+xa
Yeast growth (upon temperature abuse)食品伙伴个性空间^R'kb.b_fi
Frozen dairy products
s[2\2O0e:E0(ice cream, yogurt, etc.)
,hZrO${G6UV K0Iciness (recrystallization of ice crystals)食品伙伴个性空间w9be*_#V
Sandiness (lactose crystallization)食品伙伴个性空间n{%o0L~
Loss of flavor食品伙伴个性空间4TrqDP_a"B
Disruption of emulsion system
@+m}"@Qx:X2uD0Frozen convenience foods Rancidity in meat portions食品伙伴个性空间IC3n3mV
Weeping and curdling of sauces
,Xcp~#N1q0Loss of flavor食品伙伴个性空间SG@d|l8T#B
Discoloration食品伙伴个性空间hAZlR)qO
Package ice
yOX1P/E9`$EH(z$K0Frozen bakery products (raw dough,
5itAxqnC0bread, croissants)食品伙伴个性空间+ma ^hqE
Burst can (upon temperature abuse) (dough)食品伙伴个性空间i#O V}0ja K ?
Loss of fermentation capability (dough)
QLro%O7Dr0k0Staling (becoming leathery)
4ocr3ArC0Loss of fresh aroma
PYgppK^z019.2 Modeling of quality deterioration
)C;C|,j _019.2.1 Basic equation
&@/~6D[%w0A frozen food starts to degrade once it is produced (Figure 19.1). The rate and食品伙伴个性空间0I2w6n1d |
the degree of degradation depends on both the composition and the environmental食品伙伴个性空间&F